复制和随机化列表中的项目的位置

Question

我有一个Java中的整数Arraylist调用列表，其中包含7个元素[12, 13, 17, 18, 19, 11, 20]。我想用随机顺序在列表的最后复制相同的元素两次，所以最后有三次相同的整数（总共21项），然而，每7项随机顺序。我如何在Java中这样做？

Answer 1

只需复制清单并随机播放每次迭代。

final int DUPLICATE_AMOUNT = 3; // if you want the created array 3 times as big as the original 

List<Integer> list = getMyList(); //original list 
List<Integer> fullRandom = new ArrayList<Integer>(); 
fullRandom.addAll(list); 
for (int i = 1; i < DUPLICATE_AMOUNT; i++) { 
    List<Integer> randomList = new ArrayList<Integer>(); 
    randomList.addAll(list); 
    Collections.shuffle(randomList); 
    fullRandom.addAll(randomList); 
} 

Answer 2

只要复制列表两次，将它洗：

List<Integer> tempList = new ArrayList<>(yourList); 

for(int i = 0; i < 2; i++){ 
    Collections.shuffle(tempList, new Random(System.nanoTime())); 
    yourList.addAll(tempList); 
} 

Answer 3

// init your list 
List<Integer> initialList = new ArrayList<Integer>(); 
initialList.add(new Integer(12)); 
initialList.add(new Integer(13)); 
initialList.add(new Integer(14)); 
initialList.add(new Integer(15)); 
// create a new list that'll contain your random numbers 
List<Integer> tripleList = new ArrayList<Integer>(); 
// triple your values 
tripleList.addAll(initialList); 
tripleList.addAll(initialList); 
tripleList.addAll(initialList); 
// randomize their order 
Collections.shuffle(tripleList); 
// until is empty get the top of the list with this command. 
//A random number among your list 
tripleList.remove(0); 

Answer 4

尝试使用Collections.shuffle()，并调用它的两倍初始数据列表：

private List<Integer> shufflePositions(List<Integer> data) { 
    Collections.shuffle(data); 
    return data; 
} 

public void solve() { 
    List<Integer> data = new ArrayList<>(); 
    data.add(12); 
    data.add(13); 
    data.add(17); 
    data.add(18); 
    data.add(19); 
    data.add(11); 
    data.add(20); 
    List<Integer> result = new ArrayList<>(); 
    result.addAll(data); 
    result.addAll(shufflePositions(new ArrayList<>(data))); 
    result.addAll(shufflePositions(new ArrayList<>(data))); 
} 

Answer 5

试试这个：

List<Integer> integers = new ArrayList<>(Arrays.asList(12, 13, 17, 18, 19, 11, 20)); 

for(int i=0; i<2; i++) { 

    List<Integer> IntegersClone = new ArrayList<>(integers); 

    Collections.shuffle(IntegersClone); 

    integers.addAll(IntegersClone); 
} 

//Output : [12, 13, 17, 18, 19, 11, 20, 19, 17, 12, 11, 20, 18, 13, 20, 12, 19, 11, 18, 13, 13, 11, 17, 18, 19, 12, 17, 20] 
System.out.print(integers);