java学习心得(8)

package blog;

import java.util.Iterator; import java.util.Set; import java.util.TreeSet;

public class Test {

public static void main(String[] args) { TreeSet myset=new TreeSet(); Person person1=new Person(\ Person person2=new Person(\ Person person3=new Person(\ Person person4=new Person(\ Person person5=new Person(\

myset.add(person1); myset.add(person2); myset.add(person3); myset.add(person4); myset.add(person5); showme(myset);

}

public static void showme(Set set) { Iterator it=set.iterator(); while(it.hasNext()) {

Person temp=(Person)it.next(); System.out.println(temp); } } }

另一种方式是写一个比较器，在构造Set的时候持有该比较器的引用 package blog; import java.util.*;

public class MyComparator implements Comparator {

public int compare(Object o1, Object o2) { Person person1=(Person)o1; Person person2=(Person)o2;

return person1.getAge()-person2.getAge(); }

}

package blog;

public class Person { private String name; private int age;

public Person(String name, int age) { this.name = name; this.age = age; }

public int getAge() { return age; }

public String getName() { return name; }

public int hashCode() {

return name.hashCode()*10+age; }

public boolean equals(Object obj) { if(this==obj)return true; else{

if(this.getClass()==obj.getClass()) {

Person temp=(Person)obj;

if(this.name.equals(temp.getName())&&this.age==temp.getAge())

return true; else return false;

}

else return false; } }

public String toString() {

return \姓名:\年龄:\ }

}

package blog;

import java.util.Iterator; import java.util.Set; import java.util.TreeSet;

public class Test {

public static void main(String[] args) {

TreeSet myset=new TreeSet(new MyComparator()); Person person1=new Person(\ Person person2=new Person(\ Person person3=new Person(\ Person person4=new Person(\ Person person5=new Person(\

myset.add(person1); myset.add(person2); myset.add(person3); myset.add(person4); myset.add(person5);