import java.util.*;
public class test {
public static void main(String[] args) {
for (int i = 0; i < 10 ; i++) {
new test().a();
}
}
public void a() {
ArrayList list = new ArrayList();
int n = 13;
Random rand = new Random();
boolean[] bool = new boolean[n];
int num = 0;
for (int i = 1; i < n-1; i++) {
do {
//如果产生的数相同继续循环
num = rand.nextInt(n);
} while (bool[num]);
if (num != 0) {
bool[num] = true;
list.add(num);
}
}
System.out.println(" size："+list.size());
for (int i = 0; i < 10; i++) {
System.out.println("第"+i+"个是："+list.get(i));
}
}
}
这个怎么报错呢？
shiren1118shiren1118@126.com 10:43:34
import java.util.*;
public class test {
public static void main(String[] args) {
for (int i = 0; i < 10 ; i++) {
new test().a();
}
}
public void a() {
ArrayList list = new ArrayList();
int n = 500;
Random rand = new Random();
boolean[] bool = new boolean[n];
int num = 0;
for (int i = 1; i < n-1; i++) {
do {
//如果产生的数相同继续循环
num = rand.nextInt(n);
} while (bool[num]);
if (num != 0) {
bool[num] = true;
list.add(num);
}
}
System.out.println(" size："+list.size());
for (int i = 0; i < 100; i++) {
System.out.println("第"+i+"个是："+list.get(i));
}
}
}
这个就不会·····
什么原因？如何解决
你这是因为:当NUM=0时,有多次.并不是你想的,只有一次.要想只有一次,bool[num] = true不能放在if (num != 0) 中
[code="java"]System.out.println(" size："+list.size());
for (int i = 0; i < 10; i++) {
System.out.println("第"+i+"个是："+list.get(i));
} [/code]
size 只有9 你要输出10个肯定会报错的 汗
[code="java"]
for (int i = 0; i < 10; i++) {
System.out.println("第"+i+"个是："+list.get(i));
}
[/code]
改为
[code="java"]
for (int i = 0; i < list.size(); i++) {
System.out.println("第"+i+"个是："+list.get(i));
}
[/code]
if (num != 0) {
bool[num] = true;
list.add(num);
}
这个改成:
bool[num] = true;
if (num != 0) {
list.add(num);
}