Question

我想通过使用Math.random生成6个不同的随机数，并将它们全部存储到数组中。我怎样才能确保它们与众不同？到目前为止我只有这个，这有一个bug。我只需要1到49之间的数字。（1 +（int）（Math.random（）* 49））。

public static void main (String []args) {
    int []randomNumArray = new int [6];
    randomNumArray[0] = randomNumber();
    System.out.println(randomNumArray[0]);

    for (int i = 1; i < 6; i++) {                   
        for (int j = 0; j < i; j++) {              
            randomNumArray[i] = randomNumber();
            do {
                if (randomNumArray[i] == randomNumArray[j]) {
                    randomNumArray[i] = randomNumber();
                }
            } while(randomNumArray[i] == randomNumArray[j]);
        }
        System.out.println(randomNumArray[i]);
    }
}

//This method is for generating random numbers
public static int randomNumber (){
    return  ( 1 + (int) (Math.random() * 49) );
}

Answer 1

生成随机数并继续将它们添加到Set中，直到其大小= 6.集合只能包含唯一元素。所以，你确保独一无二。

编辑：

public static void main(String[] args)  {
        Set<Integer> intSet = new LinkedHashSet<Integer>();
        Random r = new Random();
        while (intSet.size() <= 6) {
            intSet.add(r.nextInt(49)); // or your method of generating random numbers
        }
        System.out.println(intSet);
    }

Answer 2

显然，set方法和洗牌是更有效的方法，但考虑到上下文，这里是OP代码的修改，以实现唯一性，解决＆＃34; bug＆＃34;在他的代码中。

import java.util.*;

public class Main {
    public static void main (String []args) {

        int []randomNumArray = new int [6];

        randomNumArray[0] = randomNumber();

        System.out.println(randomNumArray[0]);


        for (int i = 1; i < 6; i++)
        {                   
            int candidate;
            boolean foundMatch;
            do
            {
                candidate = randomNumber();
                foundMatch = false;
                for (int j = 0; j < i; j++)
                    if (candidate == randomNumArray[j])
                        foundMatch = true;
            } while (foundMatch);
            randomNumArray[i] = candidate;

            System.out.println(randomNumArray[i]);
        }
    }
    //This method is for generating random numbers
    public static int randomNumber (){
        return  ( 1 + (int) (Math.random() * 49) );
    }
}

如何在不使用collection.shuffle的情况下在java中生成6个不同的随机数

2 个答案: