Java中ArrayList的排序两种方法以及遍历的代码

比眉伴天荒 2022-05-27 12:46 150阅读 0赞

各种排序方法的比较,见我的博客:  
[https://blog.csdn.net/qq\_37486501/article/details/80141586][https_blog.csdn.net_qq_37486501_article_details_80141586]

## 方法一: ##

*  在类的定义中实现Comparable接口中的compareTo()方法,然后调用Collections.sort()进行排序:

import java.util.Scanner;
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.Iterator;
    class Student implements Comparable{ //使用Comparable接口
         String name;
         int score;
        public Student(String name,int score)
        {
            this.name=name;
            this.score=score;   
        }
        @Override
        public int compareTo(Object o) {
       //使用Comparable的compareTo方法
            // TODO Auto-generated method stub
            Student s=(Student) o;// Object类确定为Student类
            return s.score-this.score;//决定排序的顺序
        }   
    }
    public class Main{ 
            public static void main(String[] args){
    
                ArrayList<Student> list=new ArrayList<Student>();
                list.add(new Student("bbb",30));
                list.add(new Student("aaa",15));
                list.add(new Student("ccc",80));
                Collections.sort(list);//排序
                Iterator<Student> it=list.iterator();//迭代器输出
                while(it.hasNext())
                {
                    Student s=(Student) it.next();  //转换为Student类
                    System.out.printf("%s %d\n",s.name,s.score);
            }
          }
    }

## 方法二: ##

*  创建一个新类,实现Comparator,主函数中调用Collections.sort(要处理的集合的名字,new新类())

import java.util.Scanner;
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.Iterator;
    class Student { 
         String name;
         int score;
        public Student(String name,int score)
        {
            this.name=name;
            this.score=score;   
        }
    }
    class Stu implements Comparator<Student>{ 
        @Override
        public int compare(Student o1, Student o2) {
            // TODO Auto-generated method stub
            return o1.score-o2.score;//决定排序的顺序
        }   
    }
    
    public class Main{ 
            public static void main(String[] args){
    
                ArrayList<Student> list=new ArrayList<Student>();
            list.add(new Student("bbb",30));
            list.add(new Student("aaa",15));
            list.add(new Student("ccc",80));
            Collections.sort(list,new Stu());//排序方法
                Iterator<Student> it=list.iterator();//迭代器输出
                while(it.hasNext())
                {
                    Student s=(Student) it.next();  //转换为Student类
                    System.out.printf("%s %d\n",s.name,s.score);
            }
          }
    }

[https_blog.csdn.net_qq_37486501_article_details_80141586]: https://blog.csdn.net/qq_37486501/article/details/80141586