我有这样的需求：
我有100道试题，id是0到99，我想从中找出20道试题组成一个试卷，要求试题不重复,打乱顺序：
/**
* 产生无重复的随机数 sumInt:总样本 (0....sumInt-1)
* resultSum： 产生的随机数个数
*
* @return
*/
public static int[] randoms(int sumInt, int resultSum) {
Random r = new Random();
int temp1, temp2;
//Total sample
int send[] = new int[sumInt];//0....(sumInt-1)
for (int i = 0; i < sumInt; i++) {
send[i] = i;
}
int len = send.length;//The length of the total sample
int returnValue[] = new int[resultSum];//Random number to return
for (int i = 0; i < resultSum; i++) {
temp1 = Math.abs(r.nextInt()) % len;
temp2 = send[temp1];
returnValue[i] = temp2;
if (temp1 != len - 1) {
send[temp1] = send[len - 1];
send[len - 1] = temp2;
}
len--;
}
return returnValue;
}测试：
public static void printArray(int[] ints) {
for (int i = 0; i < ints.length; i++) {
System.out.print(ints[i]);
if (i < ints.length - 1) {
System.out.print(" ,");
}
}
System.out.println();
}
@Test
public void test_randoms(){
printArray(SystemUtil.randoms(5, 3));
}
