方法1:
package ch007;
import java.util.*;
public class ArrayListRandom {
public static void main(String[] args) {
ArrayList<Integer> arr = new ArrayList<Integer>(20);
Random random = new Random();
for(int i=0;i<20;i++) {
int x=random.nextInt(89)+10;
if(arr.indexOf(x)!=-1) {
i--;
continue;
}
arr.add(x);
}
System.out.println(arr);
}
}
方法2:
package ch007;
import java.util.*;
public class ArrayListRandom {
public static void main(String[] args) {
ArrayList<Integer> arr = new ArrayList<Integer>(20);
int x;
Random random = new Random();
for(int i=0;i<20;i++) {
do {
x=random.nextInt(89)+10;
}while(arr.indexOf(x)>=0);
arr.add(x);
}
System.out.println(arr);
}
}
注:如果想存入20个两位的偶数
把x=random.nextInt(89)+10换成x=2(random.nextInt(44)+5)*