先建立一个实体:
这个实体就是简单的学生表实体(共有id,name,age,createDatetime四个字段)
package com.test.sort;
/**
* @author wang
* @date 2018/11/29
*/
public class StudentEntity implements Comparable<StudentEntity> {
private int id;
private String name;
private int age;
private String createDatetime;
public StudentEntity(int id, String name, int age, String createDatetime) {
this.id = id;
this.name = name;
this.age = age;
this.createDatetime = createDatetime;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getCreateDatetime() {
return createDatetime;
}
public void setCreateDatetime(String createDatetime) {
this.createDatetime = createDatetime;
}
@Override
public int compareTo(StudentEntity o) {
return name.compareTo(o.getName());
}
}
在main方法我们来实现各种情况的排序:
package com.test.sort;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
/**
* @author wang
* @date 2018/11/29
*/
public class Stream {
public static void main(String[] args) {
//插入三条数据
List<StudentEntity> studentList = Arrays.asList(
new StudentEntity(1, "name1", 10, "2018-11-29"),
new StudentEntity(2, "name2", 8, "2018-11-30"),
new StudentEntity(3, "name3", 28, "2018-11-19")
);
//根据第一个字段id正序
List<StudentEntity> studentList1 = studentList.stream().sorted().collect(Collectors.toList());
//根据第一个字段id逆序
List<StudentEntity> studentList2 = studentList.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());
//根据年龄正序(int类型)
List<StudentEntity> studentList3 = studentList.stream().sorted(Comparator.comparingInt(StudentEntity::getAge)).collect(Collectors.toList());
//根据年龄逆序(int类型)
List<StudentEntity> studentList4 = studentList.stream().sorted(Comparator.comparingInt(StudentEntity::getAge).reversed()).collect(Collectors.toList());
//根据时间正序(String类型)
List<StudentEntity> studentList5 = studentList.stream().sorted(Comparator.comparing(StudentEntity::getCreateDatetime)).collect(Collectors.toList());
//根据时间逆序(String类型)
List<StudentEntity> studentList6 = studentList.stream().sorted(Comparator.comparing(StudentEntity::getCreateDatetime).reversed()).collect(Collectors.toList());
//打印结果
studentList6.forEach(student -> System.out.println("id is " + student.getId() + " ; name is " + student.getName() + "; age is " + student.getAge() + "; time is " + student.getCreateDatetime()));
}
}
配上张示例图片:
好啦,排序就完事儿了