Before components can be displayed in a user interface, they must be added to a container, a component that can hold other components. Swing containers are subclasses of java.awt.Container. This class includes methods to add and remove components from a container, arrange components using an object called a layout manager, and set up borders around the edges of a container. Containers often can be placed in other containers. All Swing components are subclasses of the abstract class JComponent.
It includes methods to set a component's size, change the background color, define the font used for any displayed text, and set up tooltips. A tooltip is explanatory text that appears when you hover the mouse over the component for a few seconds. Consider one of the simplest user interface components, a push button.
The button has a border, and it displays some text. Sometimes the button is disabled, so that clicking on it doesn't have any effect. When the user clicks on the button, it changes appearance when the mouse button is pressed and changes back when the mouse button is released.
To implement this, it is necessary to respond to mouse exit or mouse drag events. Furthermore, on many platforms, a button can receive the input focus. The button changes appearance when it has the focus. If the button has the focus and the user presses the space bar, the button is triggered. This means that the button must respond to keyboard and focus events as well. In one sense, that's all there is to GUI programming.
If you're willing to program all the drawing and handle all the mouse and keyboard events, you have nothing more to learn. However, you would either be doing a lot more work than you need to do, or you would be limiting yourself to very simple user interfaces. A typical user interface uses standard GUI components such as buttons, scroll bars, text-input boxes, and menus.
These components have already been written for you, so you don't have to duplicate the work involved in developing them. They know how to draw themselves, and they can handle the details of processing the mouse and keyboard events that concern them. ConstraintTypeDescription halignmentjavafx.geometry.HPosThe horizontal alignment of the child within its layout area.
Valignmentjavafx.geometry.VPosThe vertical alignment of the child within its layout area. Hgrowjavafx.scene.layout.PriorityThe horizontal grow priority of the child. Vgrowjavafx.scene.layout.PriorityThe vertical grow priority of the child. Marginjavafx.geometry.InsetsMargin space around the outside of the child.
By default the alignment of a child within its layout area is defined by the alignment set for the row and column. If an individual alignment constraint is set on a child, that alignment will override the row/column alignment only for that child. Alignment of other children in the same row or column will not be affected. This lesson's first project is an application that displays a frame containing no other interface components. In NetBeans, create a new Java file with the class name SimpleFrame and the package name com.java21days and then enter Listing 9.1 as the source code.
This simple application displays a frame 300×100 pixels in size and can serve as a framework—pun unavoidable—for any applications you create that use a GUI. You also can call the method setSize to set up a frame's size. Dimension is a class in the java.awt package that represents the width and height of a user interface component.
Calling the Dimension constructor creates a Dimension object representing the width and height specified as arguments. The JButton components appear in the form and their corresponding nodes are displayed in the Navigator window. The JButton components' code is also added to the form's source file which is visible in the Editor's Source view. Each of the JButtons are set to the same size as the button with the longest name. For example, you can specify the states such as the text, icon, shortcut key, tool-tip text, for all the source components. The ButtonFrame class, shown in Listing 9.2, expands on the application framework created earlier in this lesson.
A panel is created, three buttons are added to the panel, and then the panel is added to a frame. Enter the source code of Listing 9.2 into a new Java file called ButtonFrame in NetBeans, making sure to put it in the com.java21days package. When organizing or formatting a graphical user interface , a CSS file is often utilized by webpages to help clearly display design elements like the format, font, color, borders, and spacing. CSS files are commonly used with software like JavaFX, Scene Builder, and Eclipse. Though incorporating CSS files with this software may seem like a complex process, we at Leading Edge Industrial have compiled tricks and tactics to add CSS styles to your JavaFX elements. With these simple tips, formatting graphical user interfaces can become a simplified process.
The nodes that are not attached to a live scene may be created and manipulated in other threads. But, once they are attached, they cannot be manipulated by multiple threads without the risk of incorrect result and, in consequence, might corrupt the scene graph. Any long-running tasks applied on the main application thread are bound to freeze the user interface. This is clearly not acceptable from the point of view of multithreaded programming. Thread safety in a JavaFX application cannot be achieved by synchronizing thread actions. We must ensure that the programs that manipulate the scene graph must do so only from the JavaFX Application Thread.
Therefore, multithreading in JavaFX has to be handled in a different manner. However, the actual realization of the Stage depends upon the platform on which it is deployed such as a Web page, a tablet, or a desktop. A JavaFX Scene is played on the stage on which actors represented by the nodes visually interact with each other.
The Scene is the container for all content in a scene graph. The main problems of multithreading in JavaFX is that the scene graph itself is not thread-safe. It is modeled to execute on the single JavaFX Application Thread. The constructor and the initialization method init() is called in the JavaFX-Launcher thread. The start() and stop() methods are invoked in the JavaFX Application Thread.
The events also are processed on the JavaFX Application Thread. Therefore, any live manipulation on the scene must be done on the main Application Thread alone. Until now we've concentrated on adding components to our ContactEditor GUI using the IDE's alignment guidelines to help us with positioning. It is important to understand, however, that another integral part of component placement is anchoring.
Though we haven't discussed it yet, you've already taken advantage of this feature without realizing it. As mentioned previously, whenever you add a component to a form, the IDE suggests the target look and feel's preferred positioning with guidelines. Once placed, new components are also anchored to the nearest container edge or component to ensure that component relationships are maintained at runtime. In this section, we'll concentrate on accomplishing the tasks in a more streamlined fashion while pointing out the work the GUI builder is doing behind the scenes.
The IDE's GUI Builder solves the core problem of Java GUI creation by streamlining the workflow of creating graphical interfaces, freeing developers from the complexities of Swing layout managers. It does this by extending the current NetBeans IDE GUI Builder to support a straightforward "Free Design" paradigm with simple layout rules that are easy to understand and use. As you lay out your form, the GUI Builder provides visual guidelines suggesting optimal spacing and alignment of components. In the background, the GUI Builder translates your design decisions into a functional UI that is implemented using the new GroupLayout layout manager and other Swing constructs.
Whenever you resize the form, switch locales, or specify a different look and feel, your GUI automatically adjusts to respect the target look and feel's insets and offsets. Sets the vertical grow priority for the child when contained by a gridpane. If set, the gridpane will use the priority to allocate the child additional vertical space if the gridpane is resized larger than it's preferred height. Setting the value to null will remove the constraint. As Richard said everything done in this sample is vector based so it will scale when the size of the button changes.
The size of the preferred size of the button is determined by the size of the Text and Icon + the padding. So if the text content or font gets bigger or smaller the preferred size will change. It is up to the layout container to listen for that change and resize the actual button control. The layout container may make the button larger or smaller than its preferred size depending on the layout rules.
Once the button has been given a size by the layout container then the backgrounds and borders described in CSS are drawn. In many projects, the main interface object is a frame (the JFrame class in the javax.swing package). A frame is a window shown whenever you open an application on your computer. A frame has a title bar; Maximize, Minimize, and Close buttons; and other features.
To add a button or other user-interface element that allows the user to close the button, all you have to do is provide an action event handler that calls the stage's close method. We will use the default position and size, and the image should not be repeated. We need to use the BackgroundImage object to create a Background class instance. Finally, we can use the setBackground() on the root node to set the image on the background. In addition to changing the button color, we also changed the background color of our anchor pane to white, so that the gray buttons could be better seen .
For more source code and button help, visit fx experience. This certainly causes the GUI to freeze and become unresponsive. Delegating a long-running task to a separate thread frees the JavaFX Application Thread to remain responsive and can continue managing GUI interaction. But, nonetheless, the GUI must be updated according to the result obtained from the computation of the running thread.
Now we'll add the combo box that will enable users to select the format of the information that our ContactEditor application will display. As we add the JComboBox, we'll align its baseline to that of the JLabel's text. Notice once again the baseline alignment guidelines that appear to assist us with the positioning. Click the fx backgroundradius property name in the Properties column and you.
Design a GUI application using JavaFX classes to change the background color of the application using RadioButton class objects and to change the text appearance by using CheckBox class objects. Foreground Events − Those events which require the direct interaction of a user. They are generated as consequences of a person interacting with the graphical components in a Graphical User Interface.
For example, clicking on a button, moving the mouse, entering a character through keyboard, selecting an item from list, scrolling the page, etc. Sets the vertical fill policy for the child when contained by a gridpane. If set, the gridpane will use the policy to determine whether node should be expanded to fill the row or kept to it's preferred height. If not value is specified for the node nor for the row, the default value is true. Sets the horizontal grow priority for the child when contained by a gridpane.
If set, the gridpane will use the priority to allocate the child additional horizontal space if the gridpane is resized larger than it's preferred width. Most computer users today expect software to feature a graphical user interface with a variety of widgets such as text boxes, sliders, and scrollbars. The Java Class Library includes Swing, a set of packages that enable Java programs to offer a sophisticated GUI and collect user input with the mouse, keyboard, and other input devices.
Almost all GUI platforms use a single threaded event dispatching model and JavaFX is no exception. JavaFX has a unique set of challenges when dealing with multithreaded programming. The reason is that JavaFX is primarily designed to work in a more or less linear fashion. All user interface events are processed in the JavaFX Application Thread. To take full advantage of modern multicore machines, JavaFX should be able to leverage multithreading of the Java programming language. This article attempts to explain the principles of multithreading under the periphery of JavaFX programming.
In the Navigator, right-click the Form ContactEditorUI node and choose Properties in the popup menu. In the Properties dialog box, change the value of the Layout Generation Style property to Swing Layout Extensions Library. Now we need to add the three JRadioButtons to a ButtonGroup to enable the expected toggle behavior in which only one radio button can be selected at a time.
This will, in turn, ensure that our ContactEditor application's contact information will be displayed in the mail format of our choosing. It is often beneficial to set several related components, such as buttons in modal dialogues, to be the same size for visual consistency. To demonstrate this we'll add four JButtons to our ContactEditor form that will allow us to add, edit, and remove individual entries from our contact list, as shown in the following illustrations. Afterwards, we'll set the four buttons to be the same size so they can be easily recognized as offering related functionality. The JPanel component appears in the ContactEditorUI form with orange highlighting signifying that it is selected.
Move the cursor to the upper left corner of the form in the GUI Builder. When the component is located near the container's top and left edges, horizontal and vertical alignment guidelines appear indicating the preferred margins. Click in the form to place the JPanel in this location. Guarded blocks are protected areas that are not editable in Source view. You can only edit code appearing in the white areas of the Editor when in Source view.
