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JavaFX 8: Introduction by Example shows you how to use your existing Java skills to create graphically exciting client applications with the JavaFX 8 platform. It is sold on the understanding that the. Robert W. Allan, Samer Z. Al-Quran, Ying Li, and Raul C An Introduction to Islamic Finance: Theory and Practice. tailamephyli.tk For your convenience Apress has placed some of the front .. in This Book The title of the book says it all: JavaFX 8: Introduction by Example.
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Your reading intentions are also stored in your profile for future reference. To set a reading intention, click through to any list item, and look for the panel on the left hand side:. JavaFX 8: This item appears on List: Interactive Software and Hardware Section: LinearGradient Note In figure , the blackLine, rectangle, and roundRectangle shapes are all positioned by the setTranslateY method relative to the ellipse shape and to one another.
JavaFX Fundamentals 49 Listing BLACK ; ellipse. To create a color, the code uses the Color. This method takes three integer values, representing red, green, and blue components.
Another overloaded method takes three integer values and a fourth parameter with a data type of double. This fourth parameter is the alpha channel, which sets the opacity of the color. This value is between zero 0 and one 1.
Note Keep in mind that there are other ways to create color, such as by specifying hue, saturation, and brightness HSB. To create a color using HSB, you would invoke the Color. Developers who are familiar with this convention can use the Color. JavaFX Fundamentals 51 After drawing the ellipse shape, the code invokes the setFill method using a radial gradient to give the appearance of a 3D spherical object.
Next, it creates a rectangle filled with a yellow semitransparent linear gradient.
Added behind the yellow rectangle is a thick black line to demonstrate the semitransparent color. Finally, the code implements a rounded rectangle filled with a green-and-black reflective linear gradient resembling 3D tubes in a diagonal direction. Each shape and its associated color fill will be discussed in more detail in the following sections. A starting point to begin the first stop color. The end point, representing the end stop color. The proportional property to specify whether to use standard screen coordinates or unit square coordinates.
The Cycle method to specify one of the three enums: An array of stop Stop colors. Each stop containing a color will begin by painting the first stop color, then interpolating to the second stop color, and so on.
When dealing with either linear or radial gradient color, pay special attention to the proportional attribute. By setting this attribute to false, you can draw a line the gradient axis having a beginning point start X, start Y and an end point end X, end Y based on standard screen x, y coordinates.
However, if the proportional attribute is set to a value of true, the gradient axis line beginning and ending points will be represented as unit square coordinates. This means that x, y coordinates for begin and end points must be between 0. This strategy is more compact and easier to define than screen coordinates on the scene graph. Radial Gradient The amazing thing about colors with gradients is that they can often make shapes appear three- dimensional. Gradient paint allows you to interpolate between two or more colors, which gives depth to the shape.
JavaFX provides two types of gradients: For our ellipse shape you will be using a radial gradient RadialGradient. You can find this documentation at the following URL: JavaFX Fundamentals Table RadialGradient Properties Property Data Type Description focusAngle Double Angle in degrees from the center of the gradient to the focus point to which the first color is mapped.
In our example the focus angle is set to zero, the distance is set to. RED and black Color. These settings give a radial gradient to our ellipse by starting with the color red with a center position of 80, 45 upper left of the ellipse that interpolates to the color black with a distance of pixels radius. Semitransparent Gradients Next, you will see how to create the rectangle, which has a yellow semitransparent linear gradient.
For our yellow rectangle you will use a linear gradient LinearGradient paint. You can find the definitions also at the following URL: The start and end point coordinates denote where the gradient pattern begins and stops. To create the second shape in Figure , the yellow rectangle, you set the start X and Y to 0. BLACK with an alpha transparency of. These settings give a linear gradient to our rectangle from top to bottom with a starting point of 0. This is a simple linear gradient paint that is the same as the linear gradient paint LinearGradient except that the start X, Y and end X, Y values are set in a diagonal position, and the cycle method is set to reflect CycleMethod.
When specifying the cycle method to reflect CycleMethod. The following code snippet implements the rounded rectangle having a cycle method of reflect CycleMethod. Text nodes allow you to display a string of characters onto the scene graph. To create Text nodes on the JavaFX scene graph you will use the javafx. Text class.
JavaFX 8 Introductio..
Because all JavaFX scene nodes extend from javafx. Node they will inherit many capabilities such as the ability to be scaled, translated, or rotated. Shape class which provides even more capabilities than the Node class.
Because a Text node is both a Node and a Shape object it is able to perform geometric operation between two shape areas such as subtract, intersect, or union. You can also clip viewport areas with a shape similar to stenciled letters. To demonstrate drawing text, in this section you will look at a basic example of how to draw text nodes on the scene graph.
This example will touch on the following three capabilities: JavaFX Fundamentals To make things a little interesting, we will create Text nodes and produce random values for the three capabilities just mentioned.
Figure shows our drawing text example in action. Drawing text The DrawingText. The code first creates a loop to generate random x, y coordinates to position Text nodes. In the loop, it creates random RGB color components between 0 and to be applied to the Text nodes. Setting all components to zero produces black. Setting all three RGB values to produces the color white. According to the API documentation the setRotate method will rotate about the pivot point, which is the center of the untransformed layout bounds layoutBounds property.
Basically, the pivot point is the center of a node that has no transforms scaling, translating, shearing, rotating, and so on applied.
Note If you need to use a combination of transforms, such as rotate, scale, and translate, take a look at the getTransforms. For more details on the difference between bounds in local, bounds in parent, and layout bounds, please see the Javadoc documentation. The following code is used in DrawingText. Each Text node maintains a text origin property that contains the starting point of its baseline.
In Latin-based alphabets, the baseline is an imaginary line underneath letters, similar to books on a bookshelf. However, some letters, such as the lowercase j, extend below the baseline.
When specifying the x and y coordinate of the Text node you will be positioning the start of the baseline. Here you were able to position, colorize, and rotate text. In addition to the font styles I also added effects such as a drop shadow DropShadow and reflection Reflection. Changing text fonts Listing BLUE ; root. BLACK ; root. JavaFX Fundamentals With Text nodes JavaFX takes a retained-mode approach, in which nodes are using vector-based graphics rendering instead of an immediate mode rendering.
The immediate mode uses bitmap graphic rendering strategies. By using vector-based graphics you will have nifty advantages over bitmap graphics.
The major advantage is that it allows you to scale shapes and apply different effects without pixilation the jaggies. For example, in an immediate mode rendering the image becomes grainy when scaled larger; however, in retained mode you will have smooth anti-aliased shapes. The code uses the Serif, SanSerif, Dialog, and Monospaced fonts along with the drop shadow and reflection effects.
Font javafx. DropShadow javafx. Reflection The code begins by setting the title on the stage. If you are new to lambdas, in Chapter 3 you will take a closer look at the concept, but for right now you can think of it as an elegant way to iterate over collections. The font family and font name list will be printed on the console output.
This is very convenient for you to later experiment with different font styles. If you can find this font, download and install it, to get the proper rendering.
A fter listing the available fonts, the code creates a root node with a background color for its scene. To obtain a font the code invokes the static method font from the Font class. When calling the font method, you can specify the font name and the point size to return a suitable font to the caller.
Secondly, is the point size or standard sizing value for fonts. Please refer to the Javadoc documentation to see the other ways to obtain system fonts. The following lines show the creation of a Text node instance and obtaining a 30 point Serif font. Once the font is obtained the Text node setFont method is used to apply the font.
Refer to the Javadoc documentation at: In JavaFX a drop shadow is an actual effect DropShadow object and is applied to a single Text node instance without the need of multiple images layered. The DropShadow object is set to be positioned based on an x, y offset in relation to the Text node. You also have the ability to set the color of the shadow; here the code will set the shadow color to gray with 0. Opacity is a range between 0 and 1 double where 0 is transparent and 1 is fully opaque.
The ChangingTextFonts. Calling the setFraction method with 0. In other words the space between the opaque node portion and the reflection portion is adjusted by the setTopOffset method.
The top offset defaults to zero. You gained insight into the difference between the Cartesian and screen coordinate systems. This furthered your knowledge of how to draw shape nodes onto the JavaFX scene graph.
Our first example was the basic shape of a line using the JavaFX Line class. Here, you delved deeper into the common properties of the parent class Shape. Next, you explored simple, complex, and custom shapes by drawing fun cartoon-like images. After creating shapes, you learned how to paint them using colors.
You not only used standard RGB colors, you also used various built-in techniques such as a linear LinearGradient and radial RadialGradient gradient paint. Using the Text node you were able to obtain the available system fonts and also apply effects such as drop shadow DropShadow and reflection Reflection.
The goal of this chapter is to demonstrate how lambdas and properties will be used in the context of JavaFX GUI applications. Having said this, I will mainly concentrate on the common features that will be used in most of the examples in this book, and will not detail every lambda and properties feature.
The general concepts from that field are used to derive the specific behaviors that have been added to Java, which are described in this chapter. Figure shows the Greek letter lambda, which you sometimes see in connection with the topic. The Greek Symbol for Lambda 61 www. A primary goal of lambdas is to help address the lack in the Java language of a good way to express functional programming concepts.
Languages that support functional programming concepts have the ability to create anonymous unnamed functions, similar to creating objects instead of methods in Java. These function objects are commonly known as closures.
Some will argue about what a closure is and what it is not; however the main idea is that languages that support functional programming with closure syntax are able to create anonymous functions as first-class citizens.
In other words, functions or closures can be treated like objects, so that they can be assigned to variables and passed into other functions. In order to mimic closures in the previous Java world Java 1. Listing shows an example of an anonymous inner class that defines handler code for a JavaFX button when pressed. Buried deep in an anonymous inner class is a single line to output text. Look no further. Java 8 solves this issue with the use of lambda expressions closures.
Actually, under the hood the compiler is capable of optimizing code and able to reduce its footprint. In the same way other languages create closures syntactically, you will also be able to reference them and pass them into other methods. In order to achieve this ability you will later learn about functional interfaces. Syntax There are two ways to specify lambda expressions.
The following simple examples illustrate the general forms: Similar to Java methods, the parentheses are for parameters that are passed into an expression. Separating the parameter list and the expression body is the arrow symbol. The expression body or code block may or may not be surrounded by curly braces. When an expression is a one-line statement, it is evaluated and returned to the caller implicitly.
Just remember that if the method requires a return type and your code block has curly braces, you must have a return statement.
Listing shows two equivalent lambda expressions, with and without curly braces. The compiler will infer the type of the parameters depending on the context. Sometimes for readability you can optionally specify the type of each parameter.
If you specify the type, you will be required to surround the list of parameters in parentheses. One last piece of syntactic sugar is that if you have one parameter to be passed into your lambda, the parentheses can be omitted. Following is a lambda expression that has one parameter event without parentheses. Lambdas and Properties Listing When these nonlocal variables are used in lambda expressions, they need to be immutable. This is a key principle in the functional programming world.
New to the Java 8 compiler is the ability to reference variables outside the scope of an anonymous inner class or lambda expression. When using lambda expressions you can optionally reference variables scoped outside the closure function.
Typically, prior to Java 8 these nonlocal variables needed to be final immutable. This immutable state enables the compiler to better predict program behavior and thus capable of optimizing code. In Java Swing development, this occurred often when variables of the enclosing scope needed to be used inside the scope of an anonymous inner class method local variable scope.
In order to abide by the compiler rules you had to declare a variable as final. The Java 8 compiler has a new capability that will infer the intent of nonlocal variables passed into anonymous inner class methods and lambda expressions to then be converted to final immutable.
To see how we old-school Java Swing developers prior to Java 8 used to receive compile-time errors, please look at Listing The scenario is a button that will modify the text of a Swing JLabel component after the button is pressed.
Prior to Java 8, the code would not compile correctly, because the label variable needed to be declared final. Compile Error! Variable label must be final. Starting with Java 8, you can now make use of the variable capture capability with anonymous inner classes and lambda expressions.
Lambdas and Properties 65 Both of the code examples shown in Listing are identical. The difference comes when using a JDK 8 compiler. When using the Java 8 compiler, the capture variable will implicitly become final immutable , and that will occur without triggering any compilation error. Another way to think about this is to ask questions such as the following: How can I assign a lambda expression to a variable? How can I create a method with parameters that accepts lambda expressions?
Functional vs. Imperative Languages The advent of cloud computing has helped to popularize many functional programming languages. It became apparent there was a paradigm shift in problem-solving that involves extremely large datasets. A typical use case when applying functional programming techniques is the ability to iterate over datasets while performing computations in a distributed fashion so that load can be shared among nodes or CPU cores.
In contrast, imperative programming languages gather data to then be passed into a tight for-loop to be processed. Because of how data and code are coupled, this puts a lot of the burden on one thread core to process so much data. The problem needs to be decomposed to allow other threads cores to participate in the computation, which then becomes distributed. One of the advantages of functional programming is the ability to express functionality in a syntactically concise manner, but more important is the ability to pass functionality lambda expressions to methods.
Being able to pass lambda expressions to methods often fosters the concept of lazy evaluation. The opposite of lazy evaluation is eager evaluation.
Using lazy evaluations will often increase performance by avoiding unnecessary calculations. Another important topic to discuss is how functional interfaces are used as closures in the Java language.
Simply put, a functional interface is basically a single abstract method SAM. The idea of functional interfaces has been around for a very long time. For instance, those who have worked with Java threads will recall using the Runnable interface, where there is a single run method with a void return type. As an example of a functional interface, I created an interface called MyEquation with a single abstract compute method.
Once it is created, you can declare and assign variables with a lambda expression. Listing is a functional interface that has a single abstract compute method. Listing demonstrates the assignment of lambda expressions to functional interface variables. Java 8 introduces the new Stream API java. A source can be a reference to data structures such as collections or IO channels.
Such operations allow you to perform aggregate tasks. Aggregate operations are similar to the way spreadsheets can execute some computation over a series of cells, such as formatting, averaging, or summing up values. To begin using aggregate operations on collections, you will first invoke the default stream method on the java. Collection interface. Stream instance. Lambdas and Properties 67 The common built-in aggregate operations are filter, map, and forEach.
A filter allows you to pass in an expression to filter elements and returns a new Stream containing the selected items. The map operation converts or maps each element to another type and returns a new Stream containing items of the mapped type. For instance, you may want to map Integer values to String values of a stream. A forEach operation allows you to pass in a lambda expression to process each element in the stream.
A typical use case to exercise the three common aggregate operations would be this: Listing implements the use case, which exercises various aggregate operations. Following is the output from Listing Next, it outputs the original list of elements unmodified. Then the code declares a nonlocal variable to the lambda expression called threshold, to be used in a filter expression.
Next, we obtain a stream from the values collection via stream method to perform aggregate operations. The next operation is the sorted method, which sorts elements that were returned from the filter method stream. Continuing the method chaining, notice the map operation. The map method operation is able to map each element in the stream from one data type to another. Lambdas and Properties In this scenario the stream elements are Integer objects, which are mapped to String objects.
In this example the string elements are hexadecimal values. Finally, the forEach operation iterates over each element in the stream of string hex elements to be printed. To clarify, the idea of method chaining actually comes from the fluent interface pattern for API design.
Default Methods Default methods are a new way to add default implementation methods to Java interfaces.
Default methods have the effect of adding extending new behavior to interfaces without breaking compatibility. Default methods are not abstract methods but methods having implementation code. For example, adding new methods to Java interfaces can affect all implementation classes. Because of the strict contract of Java interfaces, the compiler forces the implementer to implement abstract methods, but classes that implement interfaces with default methods do not force the developer to implement those default methods.
Rather, derived classes will acquire the behavior of the default method implementation. An Example Case: Listing is the default method stream in the java. Collection interface from the Java 8 source code.
The cat kind or species can easily demonstrate default behavior that is found in some cat kinds and not others. For instance, the great cats such as lions, tigers, and jaguars are able to roar, and smaller cats can purr.
Also, a house domestic cat is able to meow. Lambdas and Properties 69 Figure Both tigers and lions have the same behavior can roar via the default roar method from the Roarable interface. With both having the same functionality in two places, later down the road things could become a major maintenance nightmare. Code for the Example To see the class diagram in Figure implemented as code, refer to Listings through To implement the class diagram I will briefly outline the three parts of the code example.
First is the set of cat interfaces with default method behaviors. Second are the concrete cat classes such as Lion, Cheetah and HouseCat. Last is the main example application, which demonstrates default methods in action. Lambdas and Properties 71 Listing The Main Application File Mixins. Lambdas and Properties mediumCat. Tiger with striped fur. Tiger is eating. Tiger is sleeping. Tiger is walking. Cheetah is eating.
Cheetah is sleeping. Cheetah is walking. Domestic Cat is eating. Domestic Cat is sleeping. Domestic Cat is walking. These interfaces provide behavior for any derived class that wants to pick and choose mixin common behaviors.
You will notice that the main interface Cat contains abstract methods getCatKind , getFurDescription , and default methods walk , eat , and sleep. As usual, the Java compiler will enforce classes implementing the Cat interface to implement the abstract methods getCatKind and getFurDescription. The default methods on the Cat interface have implementation code that serves as functionality for all cats.
These default methods will provide behavior to the Cat interface while also centralizing functionality implementation for all derived classes.
I created empty marker interfaces Roarable, Purrable, and Meowler, which contain respective default methods roar , purr and meow.
These interfaces are similar to the idea of a mixin, which in object-oriented languages allows developers to extend or add default behavior to any derived class or interface. Listing is the main class that begins by creating three cat objects: Tiger, Cheetah, and HouseCat.
It invokes all of the methods on each cat object. Listing shows a cat of type Tiger with all of its methods being invoked. Properties allow developers to add listener code to respond when the wrapped value of an object has changed or is flagged as invalid.
Also, property objects can be bound to one another. Binding behavior allows properties to update or synchronize their values based on a changed value from another property. Depending on who you talk to, you might get different explanations; however, these concepts all address the issue of how best to handle synchronization between the model and view.
What this means is that when a user interacts input with the UI view the underlying backend data store the model is automatically updated, and vice-versa. Without trying to oversimplify the concepts, I will refer you to the actual UI patterns that are involved. Because these patterns have been heavily discussed over the years, the JavaFX team has designed and implemented APIs to overcome problems that arose with these UI scenarios.
In this section you will be learning how to use JavaFX properties and bindings to synchronize between your GUI and your data objects. Properties Before the JavaFX properties API, Java Swing developers adhered to the JavaBean convention specification , which specifies that objects will contain privately scoped instance variables which have associated getter accessor and setter mutator methods.
For instance, a User class might have a private instance variable password of type String. The associated getter and setter would be the getPassword and setPassword methods, respectively. Listing shows a User class that follows the older JavaBean convention. In other words, if the getter method were named getPwd , the property would be named pwd and would have nothing to do with the attribute named password. The JavaBeans specification also provided an API that has the concept of property change support java.
PropertyChangeSupport , which allowed the developer to add handler listener code when the property changed. At the time, this solved only part of the issue of property change support. Although the JavaBeans API became a standard way to build domain objects, it still lacked robust ways to synchronize the domain models and views within a GUI application as described earlier.
Through the years the JavaBean specification and API gave rise to many third-party tools and frameworks to ease the developer experience. However, wiring up GUI components to JavaBeans using unidirectional or bidirectional binding still got pretty complicated. At times, developers would have resources that were not properly released, which led to object leaks. Developers quickly realized they needed a better way to bind and unbind GUI controls to be wired up to properties.
There are two types to be concerned about: All wrapper property classes are located in the javafx. Listed here are commonly used property classes. To see all of the property classes, please refer to the documentation in Javadoc.
SimpleBooleanProperty javafx. ReadOnlyBooleanWrapper javafx. SimpleIntegerProperty javafx. ReadOnlyIntegerWrapper javafx. SimpleDoubleProperty javafx. ReadOnlyDoubleWrapper www.
Lambdas and Properties javafx.
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SimpleStringProperty javafx. To create a string property that is capable of both readable and writable access to the wrapped value, you will use the javafx.
SimpleStringProperty class. Listing is a code snippet that demonstrates an instance of a SimpleStringProperty class and modifies the property via the set method. Thus, referencing a StringProperty exposes fewer methods of the implementation class SimpleStringProperty. You will later discover other convenient constructor methods when working with JavaBeans and Property objects.
In the case of reading the value back, you would invoke the get method or getValue , which returns the actual wrapped value String to the caller. To modify the value you simply call the set method or setValue by passing in a string. Read-Only Properties To make a property read-only you would use the wrapper classes that are prefixed with ReadOnly from the javafx.
To create a property to be read-only you will need to take two steps. First is to instantiate a read-only wrapper class and invoke the method getReadOnlyProperty to return a true read-only property object.
Listing creates a read-only string property. Lambdas and Properties 77 This code snippet actually takes two steps to obtain a read-only string property. You will notice the call to getReadOnlyProperty , which returns a read-only copy synchronized of the property. One property is read-only and can be passed to external users. The other property is read- and writable and should be used internally only. From a security perspective you should be aware of the proper steps to create a true read-only property.
In the process of rewriting the bean I also wanted to add an additional read-only property called userName to demonstrate the read-only property behavior. Listing shows the User class rewritten to use JavaFX properties.
The File User. Similar to the JavaBean property change support, JavaFX properties have constructors that will allow you to specify the bean itself, its property name, and its value. As a simple example, Listing shows the instantiations of a read-only and a read-writable property using the JavaFX property change support-based constructors. But most of all, when dealing with property change support, you will need access to the bean and its other properties.
Making the getter and setter final prevents any derived classes from overriding and possibly changing the underlying property. Property Change Support Property change support is the ability to add handler code that will respond when a property changes. JavaFX property objects contain an addListener method. This method will accept two types of functional interfaces, ChangeListener and InvalidationListener.
Recall that functional interfaces are single abstract methods which are expressed using the Java lambda syntax. All JavaFX properties are descendants of the ObservableValue and Observable interfaces method overloading , which provide the addListener methods for ChangeListener and InvalidationListener, respectively. One last thing to point out is that it is important to clean up listeners by removing them. To remove them you will invoke the removeListener method by passing into it a referenced named listener as opposed to an anonymous inner class or anonymous lambda expression.
Listing shows how to create a ChangeListener to be registered with a property. Lambdas and Properties 79 Listing shows how to create an InvalidationListener to be registered with a property. In the Javadoc documentation, the difference between a ChangeListener and InvalidationListener is described as follows: An invalidation event is generated, if the current value is not valid anymore.
This distinction becomes important, if the ObservableValue supports lazy evaluation, because for a lazily evaluated value one does not know if an invalid value really has changed until it is recomputed. For this reason, generating change events requires eager evaluation while invalidation events can be generated for eager and lazy implementations. When using the ChangeListener, you normally want eager evaluation such as the validation of properties on a form-type application.
When you access the observable value, it causes the InvalidationListener to be eager. Binding Simply put, binding has the idea of at least two values properties being synchronized.
This means that when a dependent variable changes, the other variable changes. JavaFX provides many binding options that enable the developer to synchronize between properties in domain objects and GUI controls. In this section you will learn about three binding strategies when binding property objects.
To bind a property to another property, you will invoke the bind method. This method will bind in one direction unidirectional. For instance, when property A binds to property B the change in property B will update property A, but not the other way. A bound value cannot be set. Listing is a Contact bean having a property firstName that is bound bidirectionally to a local variable fname of type StringProperty. The fluent APIs are methods that allow you to perform operations on properties using English-like method names.
For example, if you have a numeric property, there would be methods like multiply , divide , subtract , www. Lambdas and Properties 81 and so on. Another example would be a string property having methods like isEqualTo , isNotEqualTo , concat , and similar. As an example, Listing shows how to create a property that represents the formula for the area of a rectangle. IntegerExpression parent interface. This example binds by using the multiply method, which returns a NumberBinding containing the computed value.
For all available fluent interfaces, please see the Javadoc for javafx. Listing shows how to create a low-level binding for the formula for the volume of a sphere.
Next, I want to close out this chapter with an example showing how to build a snazzy-looking logon dialog window that makes use of shapes, lambda expressions, properties, and bindings with a hint of UI controls. Shown in Figure is the initial display of the logon dialog window the code will create. Initial display of the logon dialog window Following are the instructions for interacting with the application.
The user will have three attempts to enter the correct password. Figure shows the user making the first attempt to log on. The user is entering the password into the logon dialog window 2. As the user enters the password, they have an opportunity to hit the Enter key. If the password is incorrect, a red X appears to the right of the password text field.
Figure shows an invalid logon. The user has pressed Enter with an invalid password 3. If the user types the correct password in real time a green check appears. After the green check appears, the user may hit the Enter key to be granted access. Figure shows the user entering a valid password. Lambdas and Properties 83 Figure Pos; import javafx.
PasswordField; import javafx. BOLD, 30 ; userName. Lambdas and Properties 85 passwordField. When the password is incorrect, the visible property becomes false, which hides the green check node SVGPath.
Lambdas and Properties 87 In the start method, a User object is created to be used as the domain object model to be synchronized with the GUI form. Next, the stage is set to be transparent by invoking the Stage. This will allow us to create translucent and irregularly shaped windows without the decoration of the native OS title bar.
After initializing the stage, I also needed to create a Scene with a root node of type Group that will allow me to add child nodes. Even though the root node is transparent, it will need to be the same size as our logon screen.
The text node is set up with a 30 point SanSerif font having a fill color of the foregroundColor white variable. Shown in Figure in the upper-right corner of the logon dialog window is the padlock icon. Recall that in Chapter 2 we discussed generating complex shapes using path elements to create an ice cream cone, as depicted in Figure To render a path the string representing the path notation is passed into the setContent method on the SVGPath node.
To see how to use SVG paths, visit http: There I was able to obtain very nice SVG icons, at http: Next, the code creates an HBox as a container for the first row row1 to hold the userNameCell and padLock nodes. After creating the first row, the code proceeds by creating the PasswordField UI control.
I added a 20 point SanSerif font to the password field. Next, the code will set the prompt text to let the user know what to type into the field. The CSS style I applied to the password field was a white background with opacity of 80 percent. Still working with the password field, I used the fluent interface subtract to bind the preferred width to subtract 55px to allow room for the stack pane that contains the granted and denied icons.
Next, I create two more icons using the SVGPath node that represents an X and a check mark, denoting denied deniedIcon and granted grantedIcon access icons, respectively. These icons will be placed in a StackPane layout node. The StackPane layout allows child nodes to be stacked, hence the name. In this scenario the deniedIcon and grantedIcon nodes are stacked on top of each other. This trick will allows us to flip between icons using the setVisible method.
As a whole stack pane node, it will be positioned to the right of the password field. Next, the code continues by wiring up the UI controls and adding property change support ChangeListeners to various properties. The code proceeds with the passwordField by adding an action as a functional interface for the method setOnAction when the user hits the Enter key. The following handler code is set on the password field when the user hits the Enter key.
User cdea is granted access. Lambdas and Properties 89 Still working with the password field, I added a change listener to listen for keystrokes from the user. As the user types into the password field the password is compared against the stored hardcoded password.
Finally, I added the last bit of wiring for when a user has too many failed attempts. The rest is assembling the rows into a VBox layout and adding it to the root node for the scene to be shown. You were introduced to the new features in Java 8 such as lambda expressions, stream APIs, and default methods. Starting with Java lambdas, you were able to learn the syntax and make use of functional interfaces. Next, you were able to use the stream API and common aggregate functions.
After an example of using the stream APIs to manipulate elements in a collection, you then learned how to extend behavior on Java interfaces with default methods.
With a solid understanding of working with properties, you then learned about various binding strategies. With the increase of the number different screen sizes a UI developer will need to learn how to create applications with UI layout management in mind. After layouts are discussed in the first half of this chapter an example will be presented showing a form-based application. The form-based application demonstrates the resizing of child UI controls as the parent window is being resized.
JavaFX UI controls include menus, menu items, list views, table views and progress indicators. Layouts One of the greatest challenges in building user interfaces is the laying out of UI controls onto the display area. In GUI applications it is ideal to allow the user to resize a viewable area while UI controls also resize in order to provide a pleasant user experience.
Following are the JavaFX layouts discussed in this section: HBox javafx. VBox javafx. FlowPane javafx. BorderPane javafx. GridPane 91 www. As child nodes are added consecutively, each is appended to the end right side. When the parent node is not resizable a Group node, for example , the row height of the HBox takes on the height of the child node with the greatest preferred height.
Also, by default each child node aligns to the top-left Pos. The HBox can be configured to have resizing ranges to allow the parent to manage and calculate space available upon layout requests. Although in this chapter you will learn how to set constraints using a programmatic approach, there are also alternative strategies.
One well known and preferred strategy is to style or set constraints using JavaFX CSS attributes; you will catch a glimpse of that approach later in this chapter, and more details in Chapter 6, on custom UIs. In contrast, when using resizable nodes such as a TextField control, the parent has the ability to manage and compute the available space for the TextField to grow horizontally.
Nonresizable nodes such as rectangle shapes are used in the example to demonstrate the many spacing attributes for the HBox layout control. For brevity, only the relevant code is listed here.
The HBoxExample. Layouts and UI Controls 93 Figure The output of the file HBoxExample. This constructor takes a value of type double, which specifies the horizontal space in pixels between child nodes. This is also the equivalent of invoking the setSpacing method. The figure displays three gray rectangular areas, each five pixels wide, that represent the spacing between child nodes r1 to r4. Notice that the inner part of the HBox border has yellow padding one pixel wide surrounding the row.
An example of an HBox layout containing four rectangles After creating all four rectangles, the code sets the margin on rectangle r1.
The code creates an Insets object with a margin of two pixels for the top, right, bottom, and left. As shown in Figure , this is the surrounding space around rectangle r1 blue. When the parent of the HBox is a Group node not resizable , the HBox width will total 76 pixels and the height 22 pixels. As children are added, each is placed beneath the previous child node. VBox layouts can also be configured to have resizing ranges to allow the parent node to manage and calculate space available upon layout requests.
To demonstrate the use of a VBox, the example in Listing contains the same four rectangles from the previous example, with the same layout constraints. The VBoxExample. The output of VBoxExample. Figure depicts horizontal gray bars that represent the spacing between child nodes r1 to r4. After constructing the VBox, you set the padding via setPadding method.
Setting the padding by using an Insets object allows you to create padding between the border and the row. Notice in Figure the VBox padding of one pixel surrounding the VBox shown surrounded by a yellow line. Layouts and UI Controls 95 Figure VBox containing four rectangle child nodes Once the four rectangles are created, the code sets the margin on the rectangle r1.
To set the margin we use the static method VBox. The code then creates an Insets object with a margin of two pixels for the top, right, bottom, and left. Surrounding rectangle r1 is a two-pixel margin shown in blue. Depicted in Figure are four child nodes flowing from left to right and then wrapping. A FlowPane layout with nodes flowing left to right with the ability to wrap nodes based on horizontal space. The Hello text node is wrapped to the next line because the available horizontal space, denoted by the dashed line, is too small By default a FlowPane layout flows child nodes from left to right Pos.
To change the flow alignment, you can simply invoke the setAlignment method by passing in an enumerated value of type Pos. Listing creates a FlowPane layout to flow child nodes from right to left Pos. BorderPane The BorderPane layout node allows child nodes to be placed in a top, bottom, left, right, or center region.
Because each region can only have one node, developers typically nest layouts. An example would be to create an HBox with children to then be set as the top region via the setTop method. Layouts and UI Controls 97 Figure The BorderPane layout This layout is similar to many websites we see every day, where navigational links are placed in either the top, bottom, left, or right regions of a page, while the main content is in the center area.
The left and right border regions take up the available vertical space between the top and bottom borders. According to the Javadocs, the default alignment of nodes when placed in the top, bottom, left, right, and center regions is as follows: For instance, business applications typically have data entry form screens.
Forms usually have read-only labels on the first column and input fields on the second column, resembling a grid pattern. For example, if the second column contains input text fields, you may want them to resize as the window is being resized.
The most interesting part of the example is the use of column constraints on the GridPane. Column constraints apply a minimum and maximum horizontal width for the child nodes to grow or shrink as the window is resized. The GridPaneForm. RIGHT ; gridpane. LEFT ; gridpane.
JavaFX 8: Introduction by Example
When resizing the window, notice that the input text field controls grow or shrink based on the column constraints. Also notice that the Save button is horizontally aligned to the right HPos. Output of the file GridPaneForm. Layouts and UI Controls Listing begins by creating an instance of a BorderPane object as the root node for our scene.
By using a BorderPane as the root node and then placing the GridPane node object into the center region, we enable the parent BorderPane to resize the GridPane by giving it all the available horizontal and vertical space. After creating a BorderPane instance as our root node, the code instantiates a GridPane layout with padding along with horizontal and vertical gaps.
The code in Listing then creates a GridPane layout with padding, horizontal, and vertical gaps set to 5 pixels. This is very nice; it means that when the parent container node BorderPane is being resized, the GridPane will cause its child nodes to grow or shrink horizontally based on its row or column constraints. Listing demonstrates the ability to constrain the first column to pixels wide for the read-only labels and the second column with a minimum width of 50, a preferred width of and a maximum width of I set the maximum width to for the second column so you can see that the child TextField does not grow beyond the maximum width In other words, when the window is resized wider than pixels, the text fields within the grid pane column stop stretching.
The next step is simply putting each UI control into its respective cell location. All cells are relative to zero; to place a node in the cell in the first column and first row you would specify the cell as 0, 0. Thus, the following code snippet adds the Save button into the second column, third row of the GridPane layout at cell 1, 2: The following statement right-aligns the Save button: RIGHT ; www. Layouts and UI Controls After completing the GridPane setup, the code implements the top banner area of the input form shown in Figure To create a title banner, we use a flow layout with a background color of light blue, an SVG node icon people and a text node contacts.
Because the banner FlowPane is placed in the top region of the BorderPane layout, the preferred height of 40 pixels will be honored and the width will take up the available horizontal space. With this knowledge that the FlowPane takes up the available horizontal space, notice the area being filled with the light blue background color.
By using JavaFX CSS styling, the code sets a background color of light blue along with corner radii and insets specified using a string. Listing is the code section that styles the banner FlowPane to be placed in the top region of the BorderPane layout. There are other ways to provide constraints and alignment of child nodes, so I trust you will delve deeper into the GridPane layout.
Please see the Javadocs documentation for more details. UI Controls UI controls are essentially advanced JavaFX nodes that typically allow user input such as text fields, sliders, list views, and table views. This means you can treat any UI control like any other JavaFX node; for example you can scale, rotate, style, and add effects. The remainder of the chapter presents many common JavaFX UI controls that are commonly used in data entry form applications. Later sections will show how to work with table views and list views.
Menus Menus are a standard way for windowed desktop applications to allow users to select options. For example, applications typically have a File menu offering options menu items to save or open a file. In a windowed environment the user will use their mouse to navigate and select menu items.
Menus and menu items typically also have the functionality of key combinations to select options, also known as keyboard shortcuts. In other words, key combinations allow quick menu selections without the need of a mouse. For starters, you must create a menu bar javafx.BLACK ; quad. Flex 4 Cookbook. It covers advanced topics such as custom controls, JavaFX 3D, gesture devices, and embedded systems. Lambdas and Properties mediumCat.
Typically you will need administrator rights on the machine to install software. Just as you learned in a geometry classroom, you specify a width, height, and an x, y location upper-left corner to position the rectangle on the scene graph. Each chapter starts with an introduction to the topic at hand, followed by a step-by-step discussion of the topic with small snippets of code.
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