如何从Java中的数组中删除对象？ [英] How do I remove objects from an array in Java?

问题描述

由于数组的 N 对象，让我们说这是一个字符串的阵列，它具有以下值：

Given an array of n Objects, let's say it is an array of strings, and it has the following values:

foo[0] = "a";
foo[1] = "cc";
foo[2] = "a";
foo[3] = "dd";

什么我需要做删除/删除所有字符串/对象等于一数组中？

推荐答案

[如果你想要一些准备使用的code，请滚动到我的EDIT3（切后）。其余的是在这里为后人。]

[If you want some ready-to-use code, please scroll to my "Edit3" (after the cut). The rest is here for posterity.]

要充实清洁工的想法：

List<String> list = new ArrayList<String>(Arrays.asList(array));
list.removeAll(Arrays.asList("a"));
array = list.toArray(array);

编辑：现在，我使用 Arrays.asList 而不是 Col​​lections.singleton ：单身是限于一个项，而 asList 办法允许你添加其他字符串过滤掉后： Arrays.asList（A，b，C ）。

I'm now using Arrays.asList instead of Collections.singleton: singleton is limited to one entry, whereas the asList approach allows you to add other strings to filter out later: Arrays.asList("a", "b", "c").

EDIT2：上述方法保留了相同的阵列（以使阵列仍具有相同的长度）;在最后的元素设置为null。如果你想要一个的新的的数组大小完全一样需要用这个来代替：

The above approach retains the same array (so the array is still the same length); the element after the last is set to null. If you want a new array sized exactly as required, use this instead:

array = list.toArray(new String[0]);

---

EDIT3：如果您使用在同一类频繁地对这个code，您不妨考虑将其加入你的类：

---

If you use this code on a frequent basis in the same class, you may wish to consider adding this to your class:

private static final String[] EMPTY_STRING_ARRAY = new String[0];

然后函数变为：

List<String> list = new ArrayList<>();
Collections.addAll(list, array);
list.removeAll(Arrays.asList("a"));
array = list.toArray(EMPTY_STRING_ARRAY);

这将然后停止无用的空字符串数组，否则将乱丢垃圾的堆新 ED每个函数被调用时。

This will then stop littering your heap with useless empty string arrays that would otherwise be newed each time your function is called.

cynicalman的建议（见评论）也将与堆乱抛垃圾的帮助，并为公平我应该提到它：

cynicalman's suggestion (see comments) will also help with the heap littering, and for fairness I should mention it:

array = list.toArray(new String[list.size()]);

我preFER我的做法，因为它可能会更容易得到明确的大小错误的（例如，呼叫尺寸（）错误列表）。

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