nameapplet3buttons.java

来自「Java the UML Way 书中所有源码」· Java 代码 · 共 59 行

/*
 * NameApplet3Buttons.java  E.L. 2001-08-18
 *
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class NameApplet3Buttons extends JApplet {
  private Container guiContainer;
  private JTextField nameField = new JTextField(20);
  private JLabel greeting = new JLabel();

  public void init() {
    guiContainer = getContentPane();
    guiContainer.setLayout(new FlowLayout());

    JLabel nameLabel = new JLabel("What's your name?");
    guiContainer.add(nameLabel);
    guiContainer.add(nameField); 
    /*
     * Creates three buttons with color according to the text on the buttons.
     * Puts all the buttons in the guiContainer.
     */
    JButton buttonRed = new JButton("Red");
    buttonRed.setBackground(Color.red);
    guiContainer.add(buttonRed);

    JButton buttonBlue = new JButton("Blue");
    buttonBlue.setBackground(Color.blue);
    guiContainer.add(buttonBlue);

    JButton buttonCyan = new JButton("Cyan");
    buttonCyan.setBackground(Color.cyan);
    guiContainer.add(buttonCyan);
    /*
     * Creates a listener and links all the buttons to the same listener.
     */
    ButtonListener theButtonListener = new ButtonListener();
    buttonRed.addActionListener(theButtonListener);
    buttonBlue.addActionListener(theButtonListener);
    buttonCyan.addActionListener(theButtonListener);
    
    guiContainer.add(greeting);
  }

  private class ButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent event) {
      String colorName = event.getActionCommand();
      Color color;
      if (colorName.equals("Red")) color = Color.red;
      else if (colorName.equals("Blue")) color = Color.blue;
      else color = Color.cyan;
      greeting.setForeground(color);
      String name = nameField.getText();
      greeting.setText("Hallo, " + name + "!");
    }
  }
}