Collection类的Comparable

import java.util.*;/** * Comparable 接口 是所有可以"排序"的类都是实现了java.lang.Comparable接口的 Comparable接口只有一个方法compareTo(Object o) jdk1.5使用泛型 * public int compareTo(Object o) { *    this == o 返回0 *    this > o 返回正数 *    this <0 返回负数 * } *  * 实现了compareTo() 从而确定该类的对象的排序方式 * @author Administrator * */public class TestComparable {public static void main(String []args) {List list = new ArrayList();list.add(new ComparableDemo("zhudansheng",120));list.add(new ComparableDemo("zhuxiaosheng",130)); list.add(new ComparableDemo("John",1230)); list.add(new ComparableDemo("Test",1330));System.out.println(list);Collections.sort(list);System.out.println(list);}}//实现comparable接口的类必须 重写equals和hashCode方法class ComparableDemo implements Comparable{ private String name; private int age;  public ComparableDemo(String name,int age){ this.name=name; 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;}public boolean equals(Object o) {ComparableDemo comp = (ComparableDemo) o;if(comp instanceof ComparableDemo) {return this.name.equals(comp.name);}return super.equals(o);}public int hashCode() {return super.hashCode();}//比较对象的值，根据哈希码进行排序比较   使用compareTo() 方法对类的对象进行排序public int compareTo(Object o) {// TODO Auto-generated method stub ComparableDemo comp = (ComparableDemo) o; if(comp instanceof ComparableDemo) {  return  this.name.compareTo(comp.name);  //根据哈希表进行排序 // return rInt!=0 ? this.age>comp.age ? 1 : 0 : 0; } else { return super.hashCode(); } }public String toString() {return this.name +"  "+this.age;} }