Comparator和Comparable接口

最新推荐文章于 2025-12-01 18:34:47 发布

原创最新推荐文章于 2025-12-01 18:34:47 发布 · 427 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#java

本文通过实例详细介绍了Java中TreeSet集合的使用方法，包括如何利用内部比较器（实现Comparable接口）和外部比较器（实现Comparator接口）对自定义对象进行排序，并展示了两种方式在实际应用中的具体实现。

Comparator和Comparable接口

内部比较器： implements Comparable(java.lang.Comparable) 接口）
外部比较器：implements Comparator(java.util.Comparator)接口（内部类也是用这个）

import java.util.Comparator;
import java.util.Set;
import java.util.TreeSet;

/**
 * 功能：存储并输出学生的信息
 * 1。内部比较器 ： implements Comparable(java.lang.Comparable 接口）
 * 2.外部比较器
 * @author ACCI
 *
 */
public class TestTreeSet3 {

    public static void main(String[] args) {
        //内部比较器
        Set<StudentTreeSet> stu = new TreeSet<StudentTreeSet>();

        stu.add(new StudentTreeSet(1, "aaa", 20, 60));
        stu.add(new StudentTreeSet(5, "bbb", 17, 80));
        stu.add(new StudentTreeSet(2, "ccc", 18, 70));
        stu.add(new StudentTreeSet(3, "ddd", 19, 80));
        stu.add(new StudentTreeSet(4, "eee", 21, 90));
        stu.add(new StudentTreeSet(1, "aaa", 20, 60));//重复
        stu.add(new StudentTreeSet(2, "bbb", 18, 70));

        System.out.println(stu.size());
        System.out.println(stu);

        System.out.println("--------------");
        //内部类 比较
        Set<StudentTreeSet> stu1 = new TreeSet<StudentTreeSet>(new Comparator<StudentTreeSet>(){

            @Override
            public int compare(StudentTreeSet stu1, StudentTreeSet stu2) {
                if (stu1.getNo()-stu2.getNo()>0) {
                    return 1;
                }else if (stu1.getNo()-stu2.getNo()<0) {
                    return -1;
                }else {
                    //主要的比较完之后比较次要的
                    if (stu1.getName().compareTo(stu2.getName())>0) {
                        return 1;
                    }else if (stu1.getName().compareTo(stu2.getName())<0) {
                        return -1;
                    }else {
                        return 0;
                    }
                }
            }
        });

        stu1.add(new StudentTreeSet(1, "aaa", 20, 60));
        stu1.add(new StudentTreeSet(5, "bbb", 17, 80));
        stu1.add(new StudentTreeSet(2, "ccc", 18, 70));
        stu1.add(new StudentTreeSet(3, "ddd", 19, 80));
        stu1.add(new StudentTreeSet(4, "eee", 21, 90));
        stu1.add(new StudentTreeSet(1, "aaa", 20, 60));//重复元素
        stu1.add(new StudentTreeSet(2, "bbb", 18, 70));

        System.out.println(stu1.size());
        System.out.println(stu1);
    }

}

public class StudentTreeSet implements Comparable<StudentTreeSet>{
    private int no;
    private String name;
    private int age;
    private int score;
    public StudentTreeSet() {
        super();
        // TODO Auto-generated constructor stub
    }
    public StudentTreeSet(int no, String name, int age, int score) {
        super();
        this.no = no;
        this.name = name;
        this.age = age;
        this.score = score;
    }
    public int getNo() {
        return no;
    }
    public void setNo(int no) {
        this.no = no;
    }
    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;
    }
    public int getScore() {
        return score;
    }
    public void setScore(int score) {
        this.score = score;
    }
    @Override
    public int compareTo(StudentTreeSet otherStudent) {
        if (this.getNo()-otherStudent.getNo()>0) {
            return 1;
        }else if (this.getNo()-otherStudent.getNo()<0) {
            return -1;
        }else {
            //主要的比较完之后比较次要的
            if (this.getName().compareTo(otherStudent.getName())>0) {
                return 1;
            }else if (this.getName().compareTo(otherStudent.getName())<0) {
                return -1;
            }else {
                return 0;
            }
        }
    }
    @Override
    public String toString() {
        return "StudentTreeSet [no=" + no + ", name=" + name + ", age=" + age + ", score=" + score + "]\n";
    }

}