创建一个含有100个元素的数组，调用随机数函数将其初始化，然后将该数组的前50个元素的和放在第一个元素内，将该数组的后50个元素的和放在第二个元素内，最后输出该数组。

虽然编译时候有点问题！所以我做了些修改！希望别见怪！
public class Random_Sum
{
    public static void main(String[] args)
    {
        //产生随机数，并存入数组
        int[] RS = new int[100];
        int rrs1 = 0;
        int rrs2 = 0;

        for(int i = 0; i < 100; i++)
        {
            if(i < 50)
            {
                RS[i] = (int)(Math.random() * 100);
                System.out.print(RS[i]+",");
            }
            else
            {
                RS[i] = (int)(Math.random() * 100);
                System.out.print(RS[i]+",");
            }
        }
        //按要求求和
        for(int i = 0; i < 100; i++)
        {
            if(i < 50)
            {
                rrs1 = rrs1 + RS[i];
            }
            else
            {
                rrs2 = rrs2 + RS[i];
            }
        }
        //重新装入数组 的一二位置
        RS[0] = rrs1;
        RS[1] = rrs2;
        System.out.println();
        System.out.println("第一个："+RS[0]);
        System.out.println("第二个："+RS[1]);
    }
}
或者
public class Rd
{
    public static void main(String[] args)
    {
        //产生随机数，并存入数组
        int[] RS = new int[100];
        int rrs1 = 0;
        int rrs2 = 0;

        for(int i = 0; i < 100; i++)
        {
            RS[i] = (int)(Math.random() * 100);
            System.out.print(RS[i]+",");
            
        }
        //按要求求和
        for(int i = 0; i < 100; i++)
        {
            if(i < 50)
            {
                rrs1 = rrs1 + RS[i];
            }
            else
            {
                rrs2 = rrs2 + RS[i];
            }
        }
        //重新装入数组 的一二位置
        RS[0] = rrs1;
        RS[1] = rrs2;
        System.out.println();
        System.out.println("第一个："+RS[0]);
        System.out.println("第二个："+RS[1]);
    }
}