排序Java集合 [英] Sort Java Collection

问题描述

我有一个Java集合：

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

CustomObject 有 id

有没有什么办法我可以做到吗？

解决方案

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）; //使用比较器尽可能多的想要
 System.out.println（list）; 
  

此外，如果 CustomObject implements Comparable ，则只需使用 Collections.sort（list）

JDK 8的语法更简单。

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

更简单

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

显然，初始代码也可用于JDK 8。

I have a Java collection:

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

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

Is there any way I could that do that?

解决方案

Use a Comparator:

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);

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

With JDK 8 the syntax is much simpler.

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

Much simplier

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

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

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