面试回顾——List<T>排序

1、如何对List<T>排序：

public static void main(String[] args) {

        Student stu1=new Student("张三","男",25);

        Student stu2=new Student("李四","男",22);

        Student stu3=new Student("王五","男",26);

        Student stu4=new Student("赵六","男",25);

        Student stu5=new Student("麻七","男",28);

        Student stu6=new Student("二狗","男",21);

        List<Student> list=new ArrayList<Student>();

        list.add(stu1);list.add(stu2);

        list.add(stu3);list.add(stu4);

        list.add(stu5);list.add(stu6);

        System.out.println("排序前：");

        for (Student student : list) {

            System.out.println(student.toString());

        }

        Collections.sort(list, new Comparator<Student>(){

            @Override

            public int compare(Student o1, Student o2) {

                if(o1.getStuAge()>o2.getStuAge()){

                    return 1;

                }

                if(o1.getStuAge()==o2.getStuAge()){

                    return 0;

                }

                return -1;

            }

        });

        System.out.println("排序后：");

        for (Student student : list) {

            System.out.println(student.toString());

        }

    }

Java8新流式排序：

package com.concretepage;

import java.util.ArrayList;

import java.util.Comparator;

import java.util.List;

import java.util.stream.Collectors;

public class SortList {

    public static void main(String[] args) {

        List<Student> list = new ArrayList<Student>();

        list.add(new Student(1, "Mahesh", 12));

        list.add(new Student(2, "Suresh", 15));

        list.add(new Student(3, "Nilesh", 10));

//以自然序排序一个list

        System.out.println("---Natural Sorting by Name---");

        List<Student> slist = list.stream().sorted().collect(Collectors.toList());

        slist.forEach(e -> System.out.println("Id:"+ e.getId()+", Name: "+e.getName()+", Age:"+e.getAge()));

//自然序逆序元素，使用Comparator提供的reverseOrder()方法

        System.out.println("---Natural Sorting by Name in reverse order---");

        slist = list.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());

        slist.forEach(e -> System.out.println("Id:"+ e.getId()+", Name: "+e.getName()+", Age:"+e.getAge()));


//使用Comparator来排序一个list

        System.out.println("---Sorting using Comparator by Age---");

        slist = list.stream().sorted(Comparator.comparing(Student::getAge)).collect(Collectors.toList());

        slist.forEach(e -> System.out.println("Id:"+ e.getId()+", Name: "+e.getName()+", Age:"+e.getAge()));


//把上面的元素逆序

        System.out.println("---Sorting using Comparator by Age with reverse order---");

        slist = list.stream().sorted(Comparator.comparing(Student::getAge).reversed()).collect(Collectors.toList());

        slist.forEach(e -> System.out.println("Id:"+ e.getId()+", Name: "+e.getName()+", Age:"+e.getAge()));

    }

}