程序功能：创建一个带有文本区及“对话框”按钮的父窗口，单击“对话框”按钮可打开一 个自定义对话框，从中可以定义行和列的数值，关闭对话框其设置的设置会显示在父窗口的文本区中。产生界面如下图所示：
1 import javax.swing.*; 2 3 import java.awt.*; 4 import java.awt.event.*; 5 6 7 public class LX9_20 extends JFrame implements ActionListener 8 { 9 int row =10,col =40; 10 JPanel p1 = new JPanel(), p2=new JPanel(); 11 JTextArea ta = new JTextArea("文本区行数："+row+"列数："+col,row,col); 12 JScrollPane scrollPane = new JScrollPane(ta); 13 Button exit = new Button("关闭"); 14 Button dialog = new Button("对话框"); 15 JPanel panel = new JPanel(); 16 LX9_20() 17 { 18 setContentPane(panel); 19 setTitle("带有对话框的父窗口"); 20 panel.setPreferredSize(new Dimension(200, 200)); 21 panel.setLayout(new BorderLayout()); 22 panel.add("Center",p1); 23 panel.add("South",p2); 24 p1.add(scrollPane); 25 p2.add(exit); 26 p2.add(dialog); 27 exit.addActionListener(this); 28 dialog.addActionListener(this); 29 pack(); 30 show(); 31 } 32 public static void main(String args[]) 33 { 34 new LX9_20(); 35 } 36 37 @Override 38 public void actionPerformed(ActionEvent e) { 39 if(e.getSource()==exit) 40 System.exit(0); 41 else 42 { 43 MyDialog dlg = new MyDialog(this,true); 44 dlg.show(); 45 } 46 } 47 48 class MyDialog extends Dialog implements ActionListener 49 { 50 Label label1 = new Label("请输入行数"); 51 Label label2 = new Label("请输入列数"); 52 TextField rows = new TextField(50); 53 TextField columns = new TextField(50); 54 Button OK = new Button("确定"); 55 Button Cancel = new Button("取消"); 56 MyDialog(LX9_20 parent,boolean modal) 57 { 58 super(parent,modal); 59 setTitle("自定义对话框"); 60 setSize(260,140); 61 setResizable(false); 62 setLayout(null); 63 add(label1); 64 add(label2); 65 label1.setBounds(50,30,65,20); 66 label2.setBounds(50,60,65,20); 67 add(rows); 68 add(columns); 69 rows.setText(Integer.toString(ta.getRows())); 70 columns.setText(Integer.toString(ta.getColumns())); 71 rows.setBounds(120,30,90,20); 72 columns.setBounds(120,60,90,20); 73 add(OK); 74 add(Cancel); 75 OK.setBounds(60,100,60,25); 76 OK.addActionListener(this); 77 Cancel.addActionListener(this); 78 } 79 @Override 80 public void actionPerformed(ActionEvent e) { 81 if(e.getSource()==OK) 82 { 83 int row = Integer.parseInt(rows.getText()); 84 int col = Integer.parseInt(columns.getText()); 85 ta.setRows(row); 86 ta.setColumns(col); 87 ta.setText("文本区行数："+row+"列数:"+col); 88 show(); 89 } 90 dispose(); 91 } 92 } 93 }