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()));
}
}