checkbox.java

统计总和的小程序

//<applet code = "checkbox.class" height = 300 width = 200></applet>
import java.applet.*;
import java.awt.*;
import java.awt.event.*;

class P1 extends Panel
{
	ScrollPane scrollpane;
	P1()
	{
		TextField word = new TextField("全班30人买下列东西，一共需要多少钱",20);
		scrollpane=new ScrollPane(1);
		scrollpane.add(word);
		add(scrollpane);
	}
}

class P2 extends Panel
{
	Checkbox box1,box2,box3,box4;
	P2()
	{
		setLayout(new GridLayout(2,2));
		box1 = new Checkbox("5/本");
		box2 = new Checkbox("2/只");
		box3 = new Checkbox("16/本");
		box4 = new Checkbox("38/本");
		add(box1);
		add(box2);
		add(box3);
		add(box4);
	}
}

class P3 extends Panel
{
	Label label;
	TextField text;
	Button button;
	P3()
	{
	label = new Label("总金额");
	text = new TextField(10);
	button = new Button("确定");
	button.setBackground(Color.green);
	add(label);
	add(text);
	add(button);
	}
}

public class checkbox extends Applet implements ItemListener,ActionListener
{
	P1 p1;
	P2 p2;
	P3 p3;
	int a1=0,a2=0,a3=0,a4=0;
	int sum = 0;
	public void init()
	{
		p1 = new P1();
		p2 = new P2();
		p3 = new P3();
		add(p1);
		add(p2);
		add(p3);
		p2.box1.addItemListener(this);
		p2.box2.addItemListener(this);
		p2.box3.addItemListener(this);
		p2.box4.addItemListener(this);
		p3.button.addActionListener(this);
	}

	public void itemStateChanged(ItemEvent e)
	{
		if(e.getItemSelectable()==p2.box1)
		{
			a1 = 5;	
		}
		if(e.getItemSelectable()==p2.box2)
		{
			a2 = 2;	
		}
		if(e.getItemSelectable()==p2.box3)
		{
			a3 = 16;	
		}
		if(e.getItemSelectable()==p2.box4)
		{
			a4 = 38;	
		}
		sum = a1+a2+a3+a4;
		sum *= 30;
	}

	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource() == p3.button)
		{
			p3.text.setText(String.valueOf(sum));
			p2.box1.setState(false);
			p2.box2.setState(false);
			p2.box3.setState(false);
			p2.box4.setState(false);
			a1=a2=a3=a4=0;
			sum = 0;
		}
	}
}