zuoye3.java

本程序就一简单的输入上限和下限求素数程序

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class zuoye3 extends JApplet
{
	 public void init()
	 {
		qiusushupanel   qiusushu=new qiusushupanel();
		Container container=getContentPane();
		container.add(qiusushu);
	 }
}
class qiusushupanel extends JPanel implements ActionListener
{   private int i,j;
  private JTextField xiaxian=new JTextField(30);
  private JTextField shangxian=new JTextField(30);
  private JTextArea sushu=new JTextArea(150,150);
  private JScrollPane  JscrollPane=new JScrollPane(sushu);
  Label xiaxian1=new Label("请输入下限");
  Label shangxian1=new Label("请输入上限");
  Button qiusushu=new Button("求之间的素数");
  
	public qiusushupanel()
	{setLayout(null);
	add(xiaxian1);
	xiaxian1.setBounds(30,20,80,20);
	add(xiaxian);
	xiaxian.setBounds(30,50,50,20);
	add(shangxian1);
	shangxian1.setBounds(30,80,80,20);
	add(shangxian);
	shangxian.setBounds(30,110,50,20);
	add(qiusushu);
	qiusushu.setBounds(30,130,80,20);
	add(JscrollPane);
	JscrollPane.setBounds(30,160,300,300);
	qiusushu.addActionListener(this);
	DocumentListener  jianting=new jiantingqi();
	xiaxian.getDocument().addDocumentListener(jianting);
	shangxian.getDocument().addDocumentListener(jianting);
	}


  /*public void instertUpdate(DocumentEvent e)	
  {
	i=Integer.parseInt(xiaxian.getText().trim());
	j=Integer.parseInt(shangxian.getText().trim());
  }
  public void removeUpdate(DocumentEvent e)
  {
  i=Integer.parseInt(xiaxian.getText().trim());
  j=Integer.parseInt(shangxian.getText().trim());
  }
  public void changedUpdate(DocumentEvent e){}*/
	public void change()
	{
		try
		{i=Integer.parseInt(xiaxian.getText().trim());
		 j=Integer.parseInt(shangxian.getText().trim());}
		catch (NumberFormatException e){}
		 
	}
	
	
  public void actionPerformed(ActionEvent e)
  {int total=0;
	  for (int n = i; n<= j; n ++){ 
	      if (isPrime(n)){ 
	        total ++;
	        sushu.append(Integer.toString(n)+" ");
	        if(total%10==0)sushu.append("\n");
	         
	      } 
	    } 
	  }
  private boolean isPrime(int num){ 
	    if (num <= 2){ 
	      if (num == 2){ 
	        return true; 
	      } 
	      return false; 
	    } 
	    if (num%2 == 0){ 
	      return false; 
	    } 
	    for (int i = 3; i < (int)Math.sqrt(num); i ++){ 
	      if (num % i == 0){ 
	        return false; 
	      } 
	    } 
	    return true; 
	  } 
  private class jiantingqi implements DocumentListener
	{
	  public void insertUpdate(DocumentEvent e)	
	  {
		change();
	  }
	  public void removeUpdate(DocumentEvent e)
	  {
		  change();
	  }
	  public void changedUpdate(DocumentEvent e){}
	}

}