Java - 获取数组中的元素位置 [英] Java - get element position in array

问题描述

我熟悉获取数组中元素位置的方法，尤其是此处显示的方法:数组中的元素位置

I'm familiar with the ways I can get an element position in array, especially the ones showed here: Element position in array

但我的问题是我不知道如何转换此代码以满足我的需要.

But my problem is I can't figure out how to convert this code to fit my needs.

我想检查一个字符串是否在 ArrayList 中匹配，如果匹配，则该字符串在 ArrayList 中的索引是多少.

What I want to check is if a String has a match in an ArrayList and if so, what's the index of the String in the ArrayList.

烦人的部分是我设法验证字符串是否在 ArrayList 中(请参阅我的代码的第一行)

The annoying part is I managed to verify the String is in the ArrayList (see first line of my code)

listPackages 是 ArrayList

listPackages is the ArrayList

current_package 是我想在 listPackages 中找到它的位置的字符串.

current_package is the String I want to find its position in listPackages.

这是我的代码:

if (listPackages.contains(current_package)) {

        int position = -1;
        for(int j = 0; j < listPackages.size(); j++) {

            if(listPackages[j] == current_package) {
              position = j;
                  break;
              }
            }
    }

非常感谢您的帮助！

谢谢！

推荐答案

使用 indexOf:

int index = listPackages.indexOf(current_package);

请注意，您通常不应该使用 == 来比较字符串 - 这将比较 references，即两个值是否是对同一对象的引用，而不是到相等的字符串.相反，您应该调用 equals().这可能是您现有代码的问题所在，但显然使用 indexOf 简单得多.

Note that you shouldn't generally use == to compare strings - that will compare references, i.e. whether the two values are references to the same object, rather than to equal strings. Instead, you should call equals(). That's probably what was going wrong with your existing code, but obviously using indexOf is a lot simpler.

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