Comparator与Comparable实现List中某一对象属性排序

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//实体类实现 Comparable接口 进行降序排序
public class TestCompare  implements Comparable<TestCompare>{
    private  String name;

    private  int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
  
    @Override
    public String toString() {
        return "TestCompare{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    @Override
    public int compareTo(TestCompare o) {
        //降序 1,-1返回位置交换升序
复制代码
//实现comparator接口实现比较器对象
//逻辑与comparable一样
public class TestComparator implements Comparator<TestCompare> {

    public int compare(TestCompare o1, TestCompare o2) {

        if(o1.getAge()<o2.getAge()){
            return 1;
        }else if(o1.getAge()==o2.getAge()){
            return 0;
        }else {
            return -1;
        }
    }
}
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        if (this.getAge()<o.getAge()){
            return 1;
        }else if(this.getAge() == o.getAge()){
            return 0;
        }else {
            return -1;
        }
    }
}    
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复制代码
public class Test_fori {

  public static void main(String[] args) {
      TestCompare t = new TestCompare();
      TestCompare testCompare1 = new TestCompare();
      TestCompare testCompare2 = new TestCompare();
      TestCompare testCompare3 = new TestCompare();
      testCompare1.setName("cui");
      testCompare1.setAge(58);
      testCompare2.setName("hhh");
      testCompare2.setAge(99);
      testCompare3.setName("hih");
      testCompare3.setAge(12);
      ArrayList<TestCompare> list = new ArrayList<>();
      list.add(testCompare1);
      list.add(testCompare2);
      list.add(testCompare3);
      for (TestCompare t1:list
           ) {
          System.err.println(t1);
      }
    //comparator方式
   //  Collections.sort(list,new TestComparator());
    //comparable方式
      Collections.sort(list);
      System.err.println("================");
      for (TestCompare t1:list
              ) {
          System.err.println(t1);
      }
  }

复制代码

 根据age进行降序排序

 

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