perfectnumber.java

接受用户输入的的整数范围

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
/*编写applet程序，接受用户输入的的整数范围，输出这个范围之内的所有完全数。
    [完全数是指等于其所有因子之和但不包括该数本身，如6=1X2X3， 6=1+2+3，6是一个完全数]
*/
public class PerfectNumber extends JApplet implements ActionListener
{
	private JTextField fromField,toField;
	private JTextArea output;
	public void init()
	{
		Container contentPane=getContentPane();
		contentPane.setLayout(new BorderLayout());
		
		JPanel inputPanel=new JPanel();		
		inputPanel.setLayout(new FlowLayout());
		JLabel fromLabel=new JLabel("from");
		JLabel toLabel=new JLabel("to");
		fromField=new JTextField("1",5);
		toField=new JTextField("100",5);
		inputPanel.add(fromLabel);
		inputPanel.add(fromField);
		inputPanel.add(toLabel);
		inputPanel.add(toField);
		contentPane.add(inputPanel,BorderLayout.NORTH);

		JPanel outputPanel=new JPanel();
		outputPanel.setLayout(new BorderLayout());
		output=new JTextArea(4,10);
		output.setBackground(Color.GRAY);
		JLabel out=new JLabel("the perfect number include:");		
		outputPanel.add(out,BorderLayout.NORTH);
		outputPanel.add(output,BorderLayout.CENTER);
		contentPane.add(outputPanel,BorderLayout.CENTER);
		
		JButton input=new JButton("Input");
		input.addActionListener(this);
		contentPane.add(input,BorderLayout.SOUTH);
		
	}
	public void actionPerformed(ActionEvent e)
	{
		if(e.getActionCommand().equals("Input"))
		{
			int from,to;
			from=Integer.parseInt(fromField.getText().trim());
			to=Integer.parseInt(toField.getText().trim());
			if(from>to||from<0)
			output.setText("Error number!\n");
			perfect(from,to);
			output.append("end of program.\n");
		}
	}
	
	private  void  perfect(int from,int to)
	{
		
		for(int num=from;num<=to;num++)
		{
		  int sum=0;
		for(int i=1;i<num;i++)
		{
			if(num%i==0)
			sum=sum+i;
		}
		if(sum==num) output.append(Integer.toString(num)+"\n");
		}
	}
	
}