lab16_2.java

计算三角形以及圆形的面积的小程序

import java.awt.*;
import java.awt.event.*;
class mainwindow extends Frame implements ActionListener
{
	MenuBar menubar;
	Menu menu;
	MenuItem item1,item2;
	Adialog dialog1;
	Bdialog dialog2;
	mainwindow(String s)
	{
		super(s);
		setLayout(new GridLayout(1,1));
		setSize(400,200);
		setBackground(Color.white);
		setVisible(true);
		menubar = new MenuBar();
		menu = new Menu("menu");
		item1 = new MenuItem("angle");
		item2 = new MenuItem("circle");
		item1.addActionListener(this);
		item2.addActionListener(this);
		menubar.add(menu);
		menu.add(item1);
		menu.add(item2);
		setMenuBar(menubar);
		dialog1 = new Adialog(this,"angle areas");
		dialog2 = new Bdialog(this,"circle areas");
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		});
	}
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource()==item1)
		{
			dialog1.setVisible(true);
		}
		else if(e.getSource()==item2)
		{
			dialog2.setVisible(true);
		}
	}
}
class Adialog extends Dialog implements ActionListener
{
	TextField b_a = new TextField(6),b_b = new TextField(6),b_c = new TextField(6),result = new TextField(6);
	Button button = new Button("确定");
	Adialog(Frame F,String s)
	{
		super(F,s);
		setLayout(new FlowLayout());
		setSize(400,200);
		setBackground(Color.white);
		setVisible(false);
		add(new Label("输入三边长度:"));
		add(b_a);add(b_b);add(b_c);
		add(new Label("结果是:"));
		add(result);
		add(button);
		button.addActionListener(this);
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				setVisible(false);
			}
		});
	}
	public void actionPerformed(ActionEvent e)
	{
		double a=Double.valueOf(b_a.getText()).doubleValue(),
			   b=Double.valueOf(b_b.getText()).doubleValue(),
			   c=Double.valueOf(b_c.getText()).doubleValue();
		double p = (a+b+c)/2,s = Math.sqrt(p*(p-a)*(p-b)*(p-c));
		result.setText(""+s);
	}
}

class Bdialog extends Dialog implements ActionListener
{
	TextField 半径=null,结果=null;
	Button b = null;
	Bdialog(Frame F,String s)
	{
		super(F,s);
		setLayout(new FlowLayout());
		setSize(400,200);
		setBackground(Color.white);
		setVisible(false);
		半径=new TextField(10);
		结果=new TextField(10);
		b= new Button("确定");
		add(new Label("输入半径"));
		add(半径);
		add(new Label("面积是:"));
		add(结果);
		add(b);
		b.addActionListener(this);
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				setVisible(false);
			}
		});
	}
	public void actionPerformed(ActionEvent e)
	{
		double r = Double.valueOf(半径.getText()).doubleValue();
		double area = 3.1415926*r*r;
		结果.setText(""+area);
	}
}

class Lab16_2
{
	public static void main(String args[])
	{
		mainwindow window = new mainwindow("一个对话框的程序");
	}
}