/*
* TreeSet集合排序的第二种方式:
* 当元素自身不具备比较性时,或者具备的比较性不是所需要的
* 这时就需要让集合自身具备比较性
* 定义了比较器,将比较器对象作为参数传递给TreeSet集合的构造函数
*
* 当两种排序都存在时,以比较器为主。
* 定义一个类,实现Comparator接口,覆盖compare方法
*/
import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;
class Student1 implements Comparable{//该接口强制让学生具备比较性
private String name;
private int age;
Student1(String name,int age){
this.name = name;
this.age = age;
}
public int compareTo(Object obj) {
if(!(obj instanceof Student1))
throw new RuntimeException("不是学生对象");
Student1 s = (Student1)obj;
// System.out.println(this.name+"===="+s.name);
if(this.age>s.age) {
return 1;
}
if(this.age==s.age) {
return this.name.compareTo(s.name);
}
return -1;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
}
public class TreeSetDemo1 {
public static void Sop(Object obj) {
System.out.println(obj);
}
public static void main(String[] args) {
// TODO Auto-generated method stub
TreeSet ts = new TreeSet(new MyCompare());
ts.add(new Student1("lisa02",20));
ts.add(new Student1("lisa05",10));
ts.add(new Student1("lisa02",30));
ts.add(new Student1("lisa04",30));
ts.add(new Student1("lisa03",30));
Iterator it = ts.iterator();
while(it.hasNext()) {
Student1 stu = (Student1)it.next();
Sop(stu.getName()+"----"+stu.getAge());
}
}
}
class MyCompare implements Comparator{//模拟比较器
public int compare(Object o1,Object o2) {
Student1 s1 = (Student1)o1;
Student1 s2 = (Student1)o2;
int num = s1.getName().compareTo(s2.getName());
if(num==0) {
return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
// if(s1.getAge()>s2.getAge()) {
// return 1;
// }
// if(s1.getAge()==s2.getAge()) {
// return 0;
// }
// return -1;
}
return num;
}
}