Java生成10个随机数，填充一个数组，用消息框显示数组内容，后求和输出

package 随机数求和;

import javax.swing.*;

public class Sum {
public static void main(String args[])
{
String output= "10个1000以内的随机数为：\n";
int sum=0;
int a []=new int [10];
for(int i = 0;i<10;i++)
{
a[i]=(int) (Math.random()*1000);
output += " "+a[i];
sum += a[i];
}
output +="\n\n十个数的和是："+sum;

JOptionPane.showMessageDialog(null,output,"结果",
JOptionPane.PLAIN_MESSAGE);
}
}