2021-01-03

package aaa;

import java.util.*;


public class aaa {

    public static void main(String[] args) {
        List c = new ArrayList();
        Student s1=new Student("zhang",1401, 20, "computer");
        Student s2=new Student("liu",1402,19,"law");
        Student s3=new Student("wang",1403,17,"mechanical");
        Student s4=new Student("li",1409,16,"english");
        c.add(s1);
        c.add(s2);
        c.add(s3);
        c.add(1,s4);
        for(Iterator it =c.iterator();it.hasNext();){
            Student temp=it.next();
            System.out.println(temp);
        }
        
        //第一种接口排序
        Collections.sort(c);
        for(Iterator it =c.iterator();it.hasNext();){
            Student temp=it.next();
            System.out.println("1--"+temp);
        }
        //第二种接口排序
        Collections.sort(c,new Outcompare());
        for(Iterator it =c.iterator();it.hasNext();){
            Student temp=it.next();
            System.out.println("2--"+temp);
        }
        
        
        //第三种排序匿名内部类不加泛型
        Collections.sort(c,new Comparator(){

            @Override
            public int compare(Object o1, Object o2) {
                Student w1 = (Student)o1;
                Student w2 = (Student)o2;
                return w1.getAge()-w2.getAge();
            }

});

        for(Iterator it =c.iterator();it.hasNext();){
            Student temp=it.next();
            System.out.println("3--"+temp);
        }
        
        //第三种排序匿名内部类加泛型
        Collections.sort(c,new Comparator(){

            @Override
            public int compare(Student o1, Student o2) {
                return o1.getAge()-o2.getAge();
            }
});

        for(Iterator it =c.iterator();it.hasNext();){
            Student temp=it.next();
            System.out.println("4--"+temp);
        }

    }
    
}

package aaa;

public class Student implements Comparable {
    private String name;
    private int id;
    private int age;
    private String major;

    public Student(String name, int id, int age, String major) {
        super();
        this.name = name;
        this.id = id;
        this.age = age;
        this.major = major;
    }


    public int getAge() {
        return age;
    }


    public String toString() {

        return "Student [name=" + name + ", id=" + id + ", age=" + age + ", major=" + major + "]";

    }


    @Override
    public int compareTo(Object o) {
        Student s = (Student)o;
        return this.age-s.getAge();
    }


    

}

package aaa;

import java.util.Comparator;

public class Outcompare implements Comparator {

    @Override
    public int compare(Object o1, Object o2) {
        Student w1 = (Student)o1;
        Student w2 = (Student)o2;
        return w1.getAge()-w2.getAge();
    }

}