Java中排序主要通过两种方式实现
（1）Collection的sort排序的集合元素都必须是Comparable接口的实现类，该接口表示子类是可以比较的。因为实现接口必须重写抽象方法 - int compareTo(T t)。
（2）使用重载的Collections.sort(List,Comparator)方法，使用匿名内部类的方式， 实现compare(Object o1, Object o2)
DivSort .class文件
public class DivSort implements Comparable<DivSort>{ public int age; public String name; public int score; public DivSort(int age, String name, int score) { super(); this.age = age; this.name = name; this.score = score; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getScore() { return score; } public void setScore(int score) { this.score = score; } @Override public int compareTo(DivSort o) { // TODO Auto-generated method stub int i=this.getAge()-o.getAge(); return i; } }
Main方法 这里将两种方法都放到一块做实验
import java.awt.List; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; public class helloword { public static void main(String[] args) { System.out.println("Hello Word!"); ArrayList<DivSort> list=new ArrayList<DivSort>(); list.add(new DivSort(11,"zhangsan",34)); list.add(new DivSort(15,"zhangsan",34)); list.add(new DivSort(04,"zhangsan",34)); list.add(new DivSort(05,"zhangsan",34)); list.add(new DivSort(12,"zhangsan",34)); Collections.sort(list); for(DivSort l:list) { System.out.println(l.getAge()+""); } Collections.sort(list,new Comparator() { @Override public int compare(Object o1, Object o2) { // TODO Auto-generated method stub if(o1 instanceof DivSort && o2 instanceof DivSort) { DivSort d1=(DivSort)o1; DivSort d2=(DivSort)o2; return d1.getAge()-d2.getAge();} else { throw new ClassCastException("不能转换为Emp类型"); } } }); for(DivSort l:list) { System.out.println("-----------------"); System.out.println(l.getAge()+""); } } }
