raindrops.java

简单的java入门编程

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

public class Raindrops extends JFrame 
implements ActionListener,ChangeListener{
	private JPanel panel;
	private Random random;
	private javax.swing.Timer timer;
	private JSlider slider;
	private JTextField gapField;
	private JLabel gapLabel;
	
	public static void main(String[] args){
		Raindrops frame =new Raindrops();
		frame.setSize(250,300);
		frame.createGUI();
		frame.show();
	}
	private void createGUI(){
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		Container window=getContentPane();
		window.setLayout(new FlowLayout());
		random=new Random();
		
		panel=new JPanel();
		panel.setPreferredSize(new Dimension(200,200));
		panel.setBackground(Color.white);
		window.add(panel);
		
		gapLabel=new JLabel("Time Gap:");
		window.add(gapLabel);
		
		gapField=new JTextField(10);
		window.add(gapField);
		
		slider=new JSlider(JSlider.HORIZONTAL,200,2000,1000);
		window.add(slider);
		slider.addChangeListener(this);
		
		gapField.setText(Integer.toString(slider.getValue()));
		timer=new javax.swing.Timer(1000,this);
		timer.start();
	}
	public void actionPerformed(ActionEvent event){
		int x,y,size;
		Graphics paper=panel.getGraphics();
		x=random.nextInt(200);
		y=random.nextInt(200);
		size=random.nextInt(20);
		paper.fillOval(x,y,size,size);
	}
	public void stateChanged(ChangeEvent e){
		int timeGap=slider.getValue();
		gapField.setText(Integer.toString(timeGap));
		timer.setDelay(timeGap);
	}
}