prime.java

一些java的小程序.包括排序,一些bank的小计算,

import javax.swing.JOptionPane;
public class Prime
{
	public static void main(String args[])
	{
		
		int k;
		int i;
		int j;
		int n = 0;
		String input;
		int count = 0;
		String output ="";
		
		input = JOptionPane.showInputDialog("please input the count of prime numbers:");
		
		n = Integer.parseInt(input); 
		int a[];
		a = new int[1001];
		for (i = 2;; i++)
		{
			k = (int)Math.sqrt(i);
			for (j = 2; j <= k;j++)
			{
				if (i % j == 0)
				    break;    
			}   
			if (--j == k )
			{
				++count;
				a[count] = i;
			    if (count == n)
			        break;
			}
			
		}
		
		if (n <= 10)
		    for (i = 1; i <= n; i++)
		        output += a[i] + "\n";
		else
		    {
		    	for (i = 1; i <= 5; i++)
		    	    output += a[i] + "\n";
		    	output += "...\n";
		    	for (i = n-4; i <= n; i++)
		    	    output += a[i] + "\n";
		    }
		    
		output += "The " + n + "-th prime number is" + a[--i];
		
		JOptionPane.showMessageDialog(null, output,"results",JOptionPane.PLAIN_MESSAGE);
	 	
	}
}