從隨機選擇器列表中排除數字

Question

我有一個隨機選擇器代碼，可以從1到6挑選一個ex的隨機數..你能給我一種方法如何從隨機選擇的列表中排除所選擇的數字。

import java.util.Random;

Random rand = new Random();

int  n = rand.nextInt(6) + 1;

像ex一樣：1.2.3.4.5.6隨機選擇= 5 1.2.3.4.6隨機選擇= 2 1.3.4.6 ..等等

Answer 1

將所有有效數字放入ArrayList中，然后從列表中選擇一個隨機索引。 然后從列表中刪除該號碼並重復。

我的Java有點生銹，因此希望我編寫的代碼有意義：

ArrayList<int> validOptions = /**/; // make your list with all initial options

int firstIndex = random.Next(validOptions.count());
int firstPick = validOptions.get(firstIndex);
validOptions.removeAt(firstIndex);

int secondIndex = random.Next(validOptions.count());
int secondPick = validOptions.get(secondIndex);
validOptions.removeAt(firstIndex);

Answer 2

您可以將已經選擇的數字添加到ArrayList中，並選擇一個數字，直到該數字未包含在列表中。

// list of numbers that I already picked
ArrayList<Integer> randomNumbersPicked = new ArrayList<>();
// int to save the current random number
int myCurrentRandomNumber;

while(iNeedAnotherNumber){
    do {
        myCurrentRandomNumber = generateRandomNumber(a, b);
    //repeat this until the number is not in the list
    } while (randomNumbersPicked.contains(new Integer(myCurrentRandomNumber)));
    //here there is a unique random number, do what you will
    System.out.println("A new number has been picked: " + myCurrentRandomNumber);
    //add the number to the list so it wont be picked again
    randomNumbersPicked.add(new Integer(myCurrentRandomNumber));
}

最好的祝福！ Dknacht。