keyto8_1_2.java

Java程序设计第八章的课后练习题目的答案 欢迎大家来参考

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.util.*;
import java.io.*;
import javax.swing.*;

public class KeyTo8_1_2 extends JApplet 
       implements ItemListener{
	
	int row;
	int width;
    int preMusic=0;
	int wordSize=50;

	Choice name;
	AudioClip[] Music;
	Font wordFont;
	String MusicN="";
	
	public void init(){
		setSize(500,300);
		width=getWidth();
		Music=new AudioClip[7];
		for(int i=0;i<7;i++){
			Music[i]=getAudioClip(getDocumentBase(),"music"+i+".mid");
		}
		
		this.setBackground(Color.black);
		wordFont=new Font("楷体_gb2312",Font.BOLD,wordSize);

		name=new Choice();
		GridBagLayout gbLayout=new GridBagLayout();
		GridBagConstraints gbc=new GridBagConstraints();
		getContentPane().setLayout(gbLayout);;
		
		gbc.gridx=1;gbc.gridy=1;
		gbc.gridwidth=10; gbc.gridheight=1;
		gbc.anchor=GridBagConstraints.CENTER;
		gbc.weightx=10;gbc.weighty=0;
		gbc.insets=new Insets(1,2,2,5);
		gbLayout.setConstraints(name,gbc);
        name.add("爱的协奏曲");
        name.add("爱情的故事");
        name.add("丁香花");
        name.add("蒙娜丽莎");
        name.add("老鼠爱大米");
        name.add("命运");
        name.add("同桌的你");
		getContentPane().add(name);
		name.addItemListener(this);
		
		
	}

	public void paint(Graphics g){ 
         g.setFont (wordFont);
		 g.setColor (Color.red);
		 g.drawString(MusicN,(width-MusicN.length()*wordSize)/2,80);
	}
	public void itemStateChanged(ItemEvent e){
		
		ItemSelectable is=e.getItemSelectable();
		if(is==name){
			Music[preMusic].stop();
		
			row=name.getSelectedIndex();
            Music[row].loop();
            preMusic=row;
            MusicN=name.getItem(row);
			repaint();			
		}       
	}
	public void update(Graphics g){  
	 
	    g.setColor(getBackground());
	    g.fillRect(0,0,getSize().width,getSize().height);
	    g.setColor(getForeground());
	    paint(g);
	}
}