排序 Java 集合 [英] Sort Java Collection

问题描述

我有一个 Java 集合:

I have a Java collection:

Collection<CustomObject> list = new ArrayList<CustomObject>();

CustomObject 现在在显示列表之前有一个 id 字段我想按那个 id 对这个集合进行排序.

CustomObject has an id field now before display list I want to sort this collection by that id.

有什么办法可以做到吗?

Is there any way I could that do that?

推荐答案

使用 比较器:

List<CustomObject> list = new ArrayList<CustomObject>();
Comparator<CustomObject> comparator = new Comparator<CustomObject>() {
    @Override
    public int compare(CustomObject left, CustomObject right) {
        return left.getId() - right.getId(); // use your logic
    }
};

Collections.sort(list, comparator); // use the comparator as much as u want
System.out.println(list);

另外，如果CustomObject实现了Comparable，那么只需使用Collections.sort(list)

Additionally, if CustomObjectimplements Comparable, then just use Collections.sort(list)

List<CustomObject> list = getCustomObjectList();
Collections.sort(list, (left, right) -> left.getId() - right.getId());
System.out.println(list);

简单得多

List<CustomObject> list = getCustomObjectList();
list.sort((left, right) -> left.getId() - right.getId());
System.out.println(list);

最简单

List<CustomObject> list = getCustomObjectList();
list.sort(Comparator.comparing(CustomObject::getId));
System.out.println(list);

显然初始代码也可用于 JDK 8.

Obviously the initial code can be used for JDK 8 too.

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