如何从数组中删除元素 [英] How to remove element from an array

问题描述

我有一个数组，例如:

String [][] test = {{"a","1"},
                    {"b","1"},
                    {"c","1"}};

谁能告诉我如何从数组中删除一个元素.例如我想删除项目b"，使数组看起来像:

Can anyone tell me how to remove an element from the array. For example I want to remove item "b", so that the array looks like:

{{"a","1"},
 {"c","1"}}

我找不到这样做的方法.到目前为止我在这里找到的东西对我不起作用:(

I can't find a way of doing it. What I have found here so far is not working for me :(

推荐答案

不能从数组中删除元素.Java 数组的大小是在分配数组时确定的，不能更改.你能做的最好的是:

You cannot remove an element from an array. The size of a Java array is determined when the array is allocated, and cannot be changed. The best you can do is:

• 将null赋给相关位置的数组；例如

• Assign null to the array at the relevant position; e.g.

test[1] = null;

这给您留下了处理数组中 null 值所在的漏洞"的问题.(在某些情况下这不是问题……但在大多数情况下是.)

This leaves you with the problem of dealing with the "holes" in the array where the null values are. (In some cases this is not a problem ... but in most cases it is.)

创建一个删除元素的新数组；例如

Create a new array with the element removed; e.g.

String[][] tmp = new String[test.length - 1][];
int j = 0;
for (int i = 0; i < test.length; i++) {
    if (i != indexOfItemToRemove) {
        tmp[j++] = test[i];
    }
}
test = tmp;

Apache Commons ArrayUtils 类有一些静态方法可以更巧妙地做到这一点(例如 Object[] ArrayUtils.remove(Object[], int)，但事实仍然是这种方法创建了一个新的数组对象.

The Apache Commons ArrayUtils class has some static methods that will do this more neatly (e.g. Object[] ArrayUtils.remove(Object[], int), but the fact remains that this approach creates a new array object.

更好的方法是使用合适的 Collection 类型.例如，ArrayList 类型有一个方法，允许您删除给定位置的元素.

A better approach would be to use a suitable Collection type. For instance, the ArrayList type has a method that allows you to remove the element at a given position.

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