集合的比较器

这个是现学现用的。

public class Student {
private String name;

private int age;

public Student(int age) {
this.age = age;
}

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;
}

@Override
public boolean equals(Object obj) {
if(obj instanceof Student){
obj = (Student) obj;
return ((Student) obj).getName().equals(getName())? true:false;
}
return false;

}

}

//这个很重要  这个就是排序的比较器  在这里是根据学生的年龄来排序的

import java.util.Comparator;

/**
* 比较器
* @author DELL
*
*/
public class StudentCompartor implements Comparator<Student>{

@Override
public int compare(Student o1, Student o2) {
// TODO Auto-generated method stub
if(o1.getAge()>o2.getAge()){ //升序
return 1;
}
return -1;
}

}

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

public class CollectionCompareDemo {
public static void main(String[] args) {
List<Student> list = new ArrayList<Student>();
list.add(new Student(20));
list.add(new Student(30));
list.add(new Student(10));
list.add(new Student(40));

Collections.sort(list, new StudentCompartor());  //排序 传入要排序的集合和比较器
Iterator<Student> iterator = list.iterator();
while(iterator.hasNext()){
System.out.println(iterator.next().getAge());
}
}
}

输出的结果是：

10
20
30
40