Comparable接口与Comparator接口

目录

Comparable接口

使用Comparable接口进行people类按id排序

Comparator接口

使用Comparator接口打破people类原有规则按id排序

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Comparable接口

Comparable接口是设计层面的排序 在使用treeset进行添加时使用的该接口排序规则

使用Comparable接口进行people类按id排序

public class match {
    public static void main(String[] args) {
       Solution666 s=new Solution666();
       people p1=new people(4);
       people p2=new people(3);
       people p3=new people(1);
       people p4=new people(9);
       TreeSet t=new TreeSet();
       t.add(p1);
        t.add(p2);
        t.add(p3);
        t.add(p4);
        System.out.println(t);
    }
}
class people implements Comparable{
    int id;
    int name;
 public people(){
 
 }
    @Override
    public String toString() {
        return "people{" +
                "id=" + id +
                ", name=" + name +
                '}';
    }
    public people(int id) {
        this.id = id;
    }
    @Override
    public int compareTo(people o) {
        return this.id-o.id;
    }
}

排序规则从小到大

Comparator接口

在设计层面不满足自己需要的排序规则时,可使用自定义排序规则

使用Comparator接口打破people类原有规则按id排序

public class match {
    public static void main(String[] args) {
       Solution666 s=new Solution666();
       people p1=new people(4);
       people p2=new people(3);
       people p3=new people(1);
       people p4=new people(9);
       TreeSet t=new TreeSet(new Comparator() {
           @Override
           public int compare(people o1, people o2) {
               return o2.id-o1.id;
           }
       });
       t.add(p1);
        t.add(p2);
        t.add(p3);
        t.add(p4);
        System.out.println(t);
    }
}
class people implements Comparable{
    int id;
    int name;
 public people(){
 
 }
    @Override
    public String toString() {
        return "people{" +
                "id=" + id +
                ", name=" + name +
                '}';
    }
    public people(int id) {
        this.id = id;
    }
    @Override
    public int compareTo(people o) {
        return this.id-o.id;
    }
}

显而易见排序规则被改变