我怎样才能按照我想要的方式对这个 ArrayList 进行排序? [英] How can I sort this ArrayList the way that I want?

问题描述

这是一个简单的ArrayList排序程序:

Here is a simple sorting program of an ArrayList:

ArrayList<String> list = new ArrayList<String>();

list.add("1_Update");
list.add("11_Add");
list.add("12_Delete");
list.add("2_Create");

Collections.sort(list);
for (String str : list) {
  System.out.println(str.toString());
}

我期望这个程序的输出为:

I was expecting the output of this program as:

1_Update
2_Create
11_Add
12_Delete

但是当我运行这个程序时，我得到的输出为:

But when I run this program I am getting output as:

11_Add
12_Delete
1_Update
2_Create

这是为什么，我如何让 ArrayList 按照预期的输出进行排序?

Why is this and how do I get the ArrayList to sort as shown in the expected output?

推荐答案

您可以编写自定义比较器:

You could write a custom comparator:

Collections.sort(list, new Comparator<String>() {
    public int compare(String a, String b) {
        return Integer.signum(fixString(a) - fixString(b));
    }
    private int fixString(String in) {
        return Integer.parseInt(in.substring(0, in.indexOf('_')));
    }
});

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