Small GUI Program

A GUI program (usually) consists of (i) a GUI interface, (ii) listener methods, and (iii) application code. Our first GUI program does not have a listener nor any application code, and is not a useful program. But it will get us started. Here is the complete program:

import java.awt.*;
import javax.swing.*;

public class TestFrame1
{
  public static void main ( String[] args )
  {
    JFrame frame = new JFrame("Test Frame 1");
    frame.setSize(200,100);
    frame.setVisible( true );
  }
}

The setSize(200,100) method call makes the rectangular area 200 pixels wide by 100 pixels high. The setVisible(true) method call makes the frame appear on the screen. If you forget to do this, the frame object will exist as an object in memory, but no picture will appear on the screen. A call to setVisible(false) makes the frame invisible, but does not destroy the software object.

It is easy to forget to include setVisible(true). If you run your GUI program, and nothing happens, check that you have called this method.