吴裕雄--天生自然java开发常用类库学习笔记：排序及重复元素说明

import java.util.Set ;
import java.util.HashSet ;
class Person{
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public String toString(){
        return "姓名：" + this.name + "；年龄：" + this.age ;
    }
};
public class RepeatDemo01{
    public static void main(String args[]){
        Set<Person> allSet = new HashSet<Person>() ;
        allSet.add(new Person("张三",30)) ;
        allSet.add(new Person("李四",31)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("赵六",33)) ;
        allSet.add(new Person("孙七",33)) ;
        System.out.println(allSet) ;
    }
};

import java.util.Set ;
import java.util.HashSet ;
class Person{
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public boolean equals(Object obj){    // 覆写equals，完成对象比较
        if(this==obj){
            return true ;
        }
        if(!(obj instanceof Person)){
            return false ;
        }
        Person p = (Person)obj ;    // 向下转型
        if(this.name.equals(p.name)&&this.age==p.age){
            return true ;
        }else{
            return false ;
        }
    }
    public int hashCode(){
        return this.name.hashCode() * this.age    ; // 定义一个公式
    }
    public String toString(){
        return "姓名：" + this.name + "；年龄：" + this.age ;
    }
};
public class RepeatDemo02{
    public static void main(String args[]){
        Set<Person> allSet = new HashSet<Person>() ;
        allSet.add(new Person("张三",30)) ;
        allSet.add(new Person("李四",31)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("赵六",33)) ;
        allSet.add(new Person("孙七",33)) ;
        System.out.println(allSet) ;
    }
};

import java.util.Set ;
import java.util.TreeSet ;
class Person{
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public String gtoString(){
        return "姓名：" + this.name + "；年龄：" + this.age ;
    }
};
public class TreeSetDemo02{
    public static void main(String args[]){
        Set<Person> allSet = new TreeSet<Person>() ;
        allSet.add(new Person("张三",30)) ;
        allSet.add(new Person("李四",31)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("赵六",33)) ;
        allSet.add(new Person("孙七",33)) ;
        System.out.println(allSet) ;
    }
};

import java.util.Set ;
import java.util.TreeSet ;
class Person implements Comparable<Person>{
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public String toString(){
        return "姓名：" + this.name + "；年龄：" + this.age ;
    }
    public int compareTo(Person per){
        if(this.age>per.age){
            return 1 ;
        }else if(this.age<per.age){
            return -1 ;
        }else{
            return 0 ;
        }
    }
};
public class TreeSetDemo03{
    public static void main(String args[]){
        Set<Person> allSet = new TreeSet<Person>() ;
        allSet.add(new Person("张三",30)) ;
        allSet.add(new Person("李四",31)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("赵六",33)) ;
        allSet.add(new Person("孙七",33)) ;
        System.out.println(allSet) ;
    }
};

import java.util.Set ;
import java.util.TreeSet ;
class Person implements Comparable<Person>{
    private String name ;
    private int age ;
    public Person(String name,int age){
        this.name = name ;
        this.age = age ;
    }
    public String toString(){
        return "姓名：" + this.name + "；年龄：" + this.age ;
    }
    public int compareTo(Person per){
        if(this.age>per.age){
            return 1 ;
        }else if(this.age<per.age){
            return -1 ;
        }else{
            return this.name.compareTo(per.name) ;    // 调用String中的compareTo()方法
        }
    }
};
public class TreeSetDemo04{
    public static void main(String args[]){
        Set<Person> allSet = new TreeSet<Person>() ;
        allSet.add(new Person("张三",30)) ;
        allSet.add(new Person("李四",31)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("王五",32)) ;
        allSet.add(new Person("赵六",33)) ;
        allSet.add(new Person("孙七",33)) ;
        System.out.println(allSet) ;
    }
};