Java: JFrame - Window

Description

A JFrame is a window, which has a content pane which is where all components should be placed.

Constructors

You can create a frame like this:

   JFrame w = new JFrame("your title");  // title is optional

Another better way is to define a class, eg MyWindow that extends JFrame, put the code which builds the GUI in the class's constructor, and create an instance of the window from the main program. See example below.

Common methods

Assume w is a JFrame window.

// Only one of getContentPane or setContentPane.  See Content Panes
   Container c = w.getContentPane();
   w.setContentPane(Container c);
// Only one of setDefaultCloseOperation or addWindowListener See JFrame Close Box
   w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   w.addWindowListener(WindowListener listen);
// Use pack or in rare cases validate.
   w.pack();     // finalizes layout.
   w.validate(); // only used for fixed layout sizes.
// Only one of setVisible or show.  Should be last operation.
   w.setVisible(boolean visible);
   w.show();     // same as setVisible(true)
// Misc.
   w.setResizable(boolean resizeable); // allow user to resize. Default true.
   w.setJMenuBar(JMenuBar mb);         // sets menubar
   w.setTitle(String title);           // Title in title bar.
   w.setSize(int width, int height);   // See Window Size and Position.

Example

There would typically be a main method something like this.

  public static void main(String[] args {
    JFrame windo = new MyExample();
    windo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    windo.setVisible(true);
  }//end main

And a class which defines the window.

public class MyExample extends JFrame {
  public MyExample() { // constructor builds GUI
    Container content = this.getContentPane();
    content.add(...) // add components to the content
    . . .
    this.setTitle("My new window");
    this.pack();   // does layout of components.
  }//end constructor
}