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What is a JComponent?

What is a JComponent?

JComponent is an abstract class that almost all Swing components extend; it provides much of the underlying functionality common throughout the Swing component library. Just as the java. awt. Component class serves as the guiding framework for most of the AWT components, the javax. swing.

How do you use JComponent?

To use JComponent, the procedure is usually as follows:

  1. create a subclass of JComponent;
  2. override the paintComponent() method to draw whatever graphics are required;
  3. override getPreferredSize(), getMinimumSize() and getMaximumSize() to make your new component “behave” properly.

Is JButton a subclass of JComponent?

With the exception of top-level containers, all Swing components whose names begin with “J” descend from the JComponent class. For example, JPanel , JScrollPane , JButton , and JTable all inherit from JComponent .

How do you create a JComponent?

Java JComponent Example

  1. import java.awt.Color;
  2. import java.awt.Graphics;
  3. import javax.swing.JComponent;
  4. import javax.swing.JFrame;
  5. class MyJComponent extends JComponent {
  6. public void paint(Graphics g) {
  7. g.setColor(Color.green);
  8. g.fillRect(30, 30, 100, 100);

Is JFrame a JComponent?

JComponent – A base class for objects which intend to interact with Swing. JFrame – Used to represent the stuff a window should have. JComponent is an abstract class for all Swing components and you can use it as the base class for your new component. JPanel is a simple usable component you can use for almost anything.

What is a JScrollPane?

A JScrollPane provides a scrollable view of a component. When screen real estate is limited, use a scroll pane to display a component that is large or one whose size can change dynamically. Other containers used to save screen space include split panes and tabbed panes. The code to create a scroll pane can be minimal.

What is paintComponent method in Java?

By now you know that the paintComponent method is where all of your painting code should be placed. It is true that this method will be invoked when it is time to paint, but painting actually begins higher up the class hierarchy, with the paint method (defined by java. awt.

What are the subclasses of JButton class?

There are several types of buttons in Java, all are subclasses of AbstractButton.

  • command buttons: is created with class JButton. It generates ActionEvent.
  • toggle buttons: have on/off or true/false values.
  • check boxes: a group of buttons.
  • radio buttons: a group of buttons in which only one can be selected.

Should I use JFrame or JPanel?

JPanel vs JFrame both are commonly used classes available in java; JPanel can be considered as a general container, which is used in case of complex or bigger functions which require grouping of different components together; on the other hand, JFrame is generally used to host simple elements used in a window like a …

Is JavaFX better than Swing?

From a Java developer perspective, both technologies are highly useful in writing pluggable UI components. With its vast UI component library, Swing can provide added advantage to the developer, whereas when it comes to design modern and rich internet application, JavaFX can supersede Swing.

What is JViewport?

A JViewport class defines the basic scrolling model and it is designed to support both logical scrolling and pixel-based scrolling. The viewport’s child called the view is scrolled by calling JViewport.

What is JTree?

JTree is a Swing component with which we can display hierarchical data. JTree is quite a complex component. A JTree has a ‘root node’ which is the top-most parent for all nodes in the tree. A node is an item in a tree.

How to associate properties with a JComponent class?

You can associate one or more properties (name/object pairs) with any JComponent. For example, a layout manager might use properties to associate a constraints object with each JComponent it manages. You put and get properties using the putClientProperty and getClientProperty methods.

How does a JComponent create a componentui?

Each JComponent subclass that has a ComponentUI will create the ComponentUI as part of its constructor. In order to provide a particular look and feel each ComponentUI may set properties back on the JComponent that created it. For example, a custom look and feel may require JTables to have a row height of 24.

How can I align all elements to the left in jpanel?

I try to do it in the following way: JPanel panel = new JPanel(); panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS)); panel.setAlignmentX(Component.LEFT_ALIGNMENT); As a result Java use left side of all elements as a position of the element and then put all elements in the center (not left part) of the JPanel. javaalignmentjpanel Share

How are Swing components descended from the JComponent class?

With the exception of top-level containers, all Swing components whose names begin with “J” descend from the JComponent class. For example, JPanel, JScrollPane, JButton, and JTable all inherit from JComponent.

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