Java:移动数组中的项目 [英] Java: moving items in array

问题描述

我希望在数组内移动东西.

I'm looking to move things around within an Array.

我希望能够将给定数组中的最后一个项目移动到一个位置，同时将当前位置中的项目向右移动.我希望它从第一个位置移动到第二个位置，等等，而不替换当前存在的项目.

I want to be able to move the last item within the given Array to a spot while moving those in the current location to the right. I want it to move from the first spot to the second, etc. without replacing the item that is currently there.

例如)

a,b,c,d,e

假设我想移动到3" - 然后它会变成

Say I want to move to "3" - it would then become

a,b,c,e,d

我目前有以下几点:

public static void moveLastup(String[] stuff, int position) 
{
    String y = stuff[stuff.length-1];

    for (int x = stuff.length-1; x > position; x--) 
        list[x] = list[x-1];

    stuff[position] = y;
}

抱歉，我认为我还不够清楚.我希望能够做的是给出这种方法，我应该能够将最后一块移动到任何地方.

edit: sorry I don't think I was clear enough. What I want to be able to do is given this method, I should be able to move the last piece anywhere.

for (int pos = 0; pos < stuff.length; pos++)
{
    moveLastup(list,pos);
    showList(list);
}

现在，当我执行此操作时，它只会获取 for 循环中下一个列表中的最后一项例)

Now when I execute this, it simply takes the last item in the next list in the for loop ex)

e,a,b,c,d

e,d,a,b,c

e,d,c,b,a

我希望它显示

e,a,b,c,d

a,e,b,c,d

a,b,e,c,d

推荐答案

这里有一个更高效简洁的解决方案，依赖于原生实现的System.arraycopy:

Here's a more efficient and concise solution, relying on the natively implemented System.arraycopy:

public static void moveLastup(String[] arr, int pos) {
    String last = arr[arr.length-1];

    // Copy sub-array starting at pos to pos+1
    System.arraycopy(arr, pos, arr, pos + 1, arr.length - pos - 1);

    arr[pos] = last;
}

还有一些测试代码:

public static void main(String[] args) {
    String[] test = { "one", "two", "three", "four", "five" };

    // Move "five" to index 2
    moveLastup(test, 2);

    // [one, two, five, three, four]
    System.out.println(Arrays.toString(test));
}

<小时>

关于您的您正在使用和修改原始数组.如果您想在每个 moveLastup 中重新开始"，您需要处理一个副本.此代码段打印您想要的内容:

---

Regarding your edit: You're working with and modifying the original array. If you want to "start over" in each moveLastup you need to work on a copy. This snippet prints what you want:

String[] list = { "a", "b", "c", "d", "e" };

for (int pos = 0; pos < list.length; pos++) {
    String[] tmpCopy = list.clone();
    moveLastup(tmpCopy, pos);
    showList(tmpCopy);
}

输出:

[e, a, b, c, d]
[a,e, b, c, d]
[a, b,e, c, d]
[a, b, c,e, d]
[a, b, c, d,e]

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