您的位置：首页 > 其它

ArrayList容器排序 comparator接口与comparable接口的使用

2016-10-08 20:03 489 查看

1、实体类实现comparable接口，重写compareTo方法

package io;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Student implements Comparable<Student>{

private String name;
private int age;
private Date birthDay;

public Student(String name, int age, String birthDay) {
super();
this.name = name;
this.age = age;

DateFormat ds=new SimpleDateFormat("yyyy-MM-dd");
try {
this.birthDay = ds.parse(birthDay);
} catch (ParseException e) {
e.printStackTrace();
};
}

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 Date getBirthDay() {
return birthDay;
}
public void setBirthDay(Date birthDay) {
this.birthDay = birthDay;
}

//按名字降序 按生日升序
@Override
public int compareTo(Student o) {
int result=0;
result=-this.name.compareTo(o.name);
if(result==0){
result=this.birthDay.compareTo(o.birthDay);
}
return result;
}

@Override
public String toString() {
return "Student [name=" + name + ", age=" + age + ", birthDay=" + birthDay + "]";
}

}

package io;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class App {

public static void main(String[] args) {

List<Student> list=new ArrayList<Student>();
list.add(new Student("张三", 20, "1987-10-5"));
list.add(new Student("王五", 22, "1986-10-5"));
list.add(new Student("赵六", 25, "1988-10-5"));
list.add(new Student("王七", 19, "1980-10-5"));
Collections.sort(list);
for(Student s:list){
System.out.println(s);
}
}
}

2、创建新的业务类实现comparator接口，重写compare方法。

package io;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Student {

private String name;
private int age;
private Date birthDay;

public Student(String name, int age, String birthDay) {
super();
this.name = name;
this.age = age;

DateFormat ds=new SimpleDateFormat("yyyy-MM-dd");
try {
this.birthDay = ds.parse(birthDay);
} catch (ParseException e) {
e.printStackTrace();
};
}

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 Date getBirthDay() {
return birthDay;
}
public void setBirthDay(Date birthDay) {
this.birthDay = birthDay;
}

@Override
public String toString() {
return "Student [name=" + name + ", age=" + age + ", birthDay=" + birthDay + "]";
}

}

package io;

import java.util.Comparator;

public class BirthdayComp implements Comparator<Student>{

@Override
public int compare(Student o1, Student o2) {

return o1.getBirthDay().compareTo(o2.getBirthDay());
}

}

package io;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class App {

public static void main(String[] args) {

List<Student> list=new ArrayList<Student>();
list.add(new Student("张三", 20, "1987-10-5"));
list.add(new Student("王五", 22, "1986-10-5"));
list.add(new Student("赵六", 25, "1988-10-5"));
list.add(new Student("王七", 19, "1980-10-5"));
Collections.sort(list, new BirthdayComp());
for(Student s:list){
System.out.println(s);
}
}
}

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航