本题的功能是用按钮来控制文本框中文本的颜色。窗口中有两个带有文字标题的面板“Sample text”和“Text color control”，窗口的底部还有一个复选按钮“Disable changes”。在“Sample text”面板中有一个带有字符串的文本框，而在“Text color control”面板中有三个按钮“Black”、“Red”和“Green”，并且每个按钮上都有一个对应颜色的圆。单击任意按钮，文本框的文本变成对应的颜色，如果选中“Disable changes”复选框，则三个颜色按钮变为不可用，如果取消选中复选框，则三个按钮变为可用。 import javax.swing.*; import java.awt.*; import java.awt.event.*; public class java3 extends JFrame private JPanel upper,middle,lower; private JTextField text; private JButton black,red,green; private JCheckBox disable; public java3(String titleText) super(titleText); addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); upper=new JPanel(); upper.setBorder(BorderFactory.createTitledBorder("Sample text")); Upper.setlayout(new BorderLayout()); text=new JTextField("Change the color of this text"); upper.add(text,BorderLayout,CENTER); middle=new JPanel(); middle.setBorder(BorderFactory.createTitledBorder("Text color control")); middle.setLayout(new FlowLayout(FlowLayout.CENTER)); black=new JButton("Black",new Colorlcon(Color.black)); black.addActionListener(new ButtonListener(Color.black)); middle.add(black); red=new JButton("Red",new Colorleon(Color.red)); red.addActionListener(new ButtonListener(Color.red)); middle.add(red); green=new JButton("Green",new Colorlcon(Color.green)); green.addActionListener(new ButtonListener(Color.green)); middle.add(green); lower=new JPanel(); lower.setLayout(new FlowLayout(FlowLayout.RIGHT)); disable=new JCheckBox("Disable changes"); disable.addhemListener(new ItemListener() public void itemStateChanged(ItemEvent e) boolean enabled =(e.getStateChange() ==ItemEvent.DESELECTED); black.setEnabled(enabled); red.setEnabled(enabled); green.setEnabled(enabled); ); lower.add(disable); Container cp=getContentPane(); cp.add(upper,BorderLayout.NORTH); cp.add(middle,BorderLayout.CENTER); cp.add(lower,BorderLayout.SOUTH); pack(); setVisible(true); class ButtonListener extends ActionListener private Color c; public ButtonListener(Color c) this.c=c; public void actionPerformed(ActionEvent e) text.setForeground(c); class Colorlcon implements Icon private Color c; private static final int DIAMETER=10; public ColorIcon(Color c) c=c; public void paintIcon(Component cp,Graphics g, int x,int y) g.setColor(c); g.fillOval(x,y,DIAMETER,DIAMETER); g.setColor(Color.black); g.drawOval(x,y,DIAMETER,DIAMETER); public int getIconHeight() return DIAMETER; public int getIconWidth() return DIAMETER; public static void main(String[]args) new java3("java3");