appgraphinout.java

java程序设计源代码

import java.awt.*;
import java.awt.event.*;

public class AppGraphInOut
{
	public static void main( String args[] )
	{
		new AppFrame();
	}
}

class  AppFrame extends Frame
{
	TextField in = new TextField(10);
	Button btn = new Button("求平方");
	Label out = new Label("用于显示结果的标签");

	public AppFrame()
	{
		setLayout( new FlowLayout() );
		add( in );
		add( btn );
		add( out );
		btn.addActionListener( new BtnActionAdapter() );
		setSize( 400,100 );
		show();
	}

	class BtnActionAdapter implements ActionListener
	{
		public void actionPerformed( ActionEvent e )
		{
			String s = in.getText();
			double d = Double.parseDouble( s );
			double sq = d * d;
			out.setText( d + "的平方是：" + sq );
		}
	}

}