factors.java

是<java程序设计>的课后作业2-8源码.可以供初学者参考,作了解java基础语法所用.

/**
 * @(#)Factors.java
 *
 *
 * @author 
 * @version 1.00 2009/3/3
 */
 //本程序是将一个正整数分解为质因子(幂)之积的形式
import javax.swing.JOptionPane;
public class Factors {
        
    /**
     * Creates a new instance of <code>Factors</code>.
     */
    public Factors() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        //int num=26;
        String stringNum=JOptionPane.showInputDialog(null,"Please input a number ,for example,26:",
        "Execise3.21 Input",JOptionPane.QUESTION_MESSAGE);
        int num=Integer.parseInt(stringNum);
        int prime=2;
        while(prime<=num)
        {        
        	boolean primeFlag=IsPrime(prime);
        	if(primeFlag)
        	while(num%prime==0)
        	{
        		System.out.print(prime+" ");
        		num/=prime;        		
        	}
        	prime++;
        }
        return ;
    }
    
    //自定义一个静态的私有的方法,用于测试素数.
    //O(n^1/2)
    private static boolean IsPrime(int testNumber)
    {
    	int i=(int)(Math.sqrt(testNumber));
    	for(int m=2;m<=i;m++)
    	{
    		if(testNumber%m==0)
    			return false;
    	}
    	return true;
    }
}