7.18. (Optional GUI) Creating Windows |
When you develop programs to create graphical user interfaces, you will use Java classes such as JFrame , JButton , JRadioButton , JComboBox , and JList to create frames , buttons, radio buttons , combo boxes, lists, and so on. Listing 7.14 is an example that creates two windows using the JFrame class. The output of the program is shown in Figure 7.28.
1 import javax.swing.JFrame; 2 3 public class TestFrame { 4 public static void main(String[] args) { 5 JFrame frame1 = new JFrame(); 6 frame1.setTitle( "Window 1" ); 7 frame1.setSize( 200 , 150 ); 8 frame1.setLocation( 200 , 100 ); 9 frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 10 frame1.setVisible( true ); 11 12 JFrame frame2 = new JFrame(); 13 frame2.setTitle( "Window 2" ); 14 frame2.setSize( 200 , 150 ); 15 frame2.setLocation( 410 , 100 ); 16 frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 17 frame2.setVisible( true ); 18 } 19 } |
This program creates two objects of the JFrame class (lines 5, 12) and then uses the methods setTitle , setSize , setLocation , setDefaultCloseOperation , and setVisible to set the properties of the objects. The setTitle method sets a title for the window (lines 6, 13). The setSize method sets the window's width and height (lines 7, 14). The setLocation method specifies the location of the window's upper-left corner (lines 8, 15). The setDefaultCloseOperation method terminates the program when the frame is closed (lines 9, 16). The setVisible method displays the window. You can add graphical user interface components , such as buttons, labels, text fields, combo boxes, lists, and menus , to the window. The components are defined using classes. GUI programming will be introduced in Part 3, "GUI Programming."