import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Num01 {

    static List<Integer> numList = new ArrayList<>();

    public static void createNum(){
        List<Integer> list = new ArrayList<>();
        for(int i = 0;i<10;i++){
            list.add(i);
        }
        Random random 
 
= new Random();
        int num = 0;
        for(int i = 0;i < 4;i++){
            int index = random.nextInt(list.size());
            if(index == 0) index++;
            numList.add(list.get(index));
            num = num * 10 + list.get(index);
            list.remove(index);
        }
        System.out.println(num);
    }

    
 
public static void main(String[] args) {
        createNum();
    }
}

java小遊戲——猜數字