TreeMap

最新推荐文章于 2024-09-26 05:30:00 发布

乐无莜

最新推荐文章于 2024-09-26 05:30:00 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/tiantian_kuaile/article/details/48272979

本文详细介绍了如何在Java中实现一个学生类，包括属性定义、构造方法、getter/setter方法、hashCode和equals方法，以及如何利用Comparator自定义排序规则。并通过创建TreeMap实例，将学生对象作为键，地址作为值进行存储，展示了如何根据学生薪资进行排序。

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package com.phone.week4;

public class Student2 implements Comparable{

private String name;
private int age;
private double salay;

public double getSalay() {
    return salay;
}
public void setSalay(double salay) {
    this.salay = salay;
}
public Student2(String name, int age) {
    super();
    this.name = name;
    this.age = 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 int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + age;
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Student2 other = (Student2) obj;
    if (age != other.age)
        return false;
    if (name == null) {
        if (other.name != null)
            return false;
    } else if (!name.equals(other.name))
        return false;
    return true;
}
@Override
public int compareTo(Student2 o) {
    if(this.getAge()==o.getAge()){
        return this.getName().compareTo(o.getName());
    }else if(this.getAge()>o.getAge()){
        return -1;
    }
    else{
        return 1;
    }
}

@Override
public String toString() {
    return "Student2 [name=" + name + ", age=" + age + ", salay=" + salay
            + "]";
}
public Student2(String name, int age, double salay) {
    super();
    this.name = name;
    this.age = age;
    this.salay = salay;
}

}

package com.phone.week4;

import java.util.Comparator;
import java.util.Map;
import java.util.TreeMap;

public class TestTreeMap {

public static void main(String[] args) {
    //把学生做为键，把学生对应的地址做为值
    //Map<Student2, String> map = new TreeMap<>();
    //Map<Student2, String> map = new TreeMap<>(new MyCompare()); 
    Map<Student2, String> map = new TreeMap<>(new Comparator<Student2>() {

        @Override
        public int compare(Student2 o1, Student2 o2) {
            if(o1.getSalay()==o2.getSalay()){
                return 0;
            }else if(o1.getSalay()>o2.getSalay()){
                return -1;
            }else{
                return 1;
            }
        }
    });
    map.put(new Student2("rainbow", 12,10000), "英国");
    map.put(new Student2("amy", 22,20000), "美国");
    map.put(new Student2("edward", 43,2000), "埃塞鹅比亚");
    map.put(new Student2("bill", 3,50000), "西班牙");
    map.put(new Student2("amy", 56,3500), "南非");
    map.put(new Student2("amy", 56,5099), "南非");

    for (Student2 key : map.keySet()) {
        System.out.println(key+"===="+map.get(key));
    }
}

private static void test1() {
    Map<String, String> map = new TreeMap<>();
    map.put("rainbow", "彩虹");
    map.put("amy", "艾咪");
    map.put("edward", "爱德华");
    map.put("bill", "比尔");

    for (String key : map.keySet()) {
        System.out.println(key+"====="+map.get(key));
    }
}

}