优先队列 java PriorityQueue

/*

PriorityQueue中主要用到的就是Heap排序

*/

import java.util.PriorityQueue;
public class Main {
//队首为最大
static class Dog implements Comparable<Dog>{
private int num;
public Dog(int num){
this.num=num;
}
public int getNum(){
return this.num;
}
@Override
public int compareTo(Dog o) {
// TODO Auto-generated method stub
if(o.getNum()<=this.num)
return -1;
return 1;
}
}
//队首为最小
static class Cat implements Comparable<Cat>{
private int num;
public Cat(int num) {
// TODO Auto-generated constructor stub
this.num=num;
}
public int getNum(){
return this.num;
}
@Override
public int compareTo(Cat o) {
// TODO Auto-generated method stub
if(o.getNum()<=this.num)
return 1;
return -1;
}
}
public static void main(String[] args){
PriorityQueue<Dog> p0=new PriorityQueue<Dog>();
PriorityQueue<Cat> p1=new PriorityQueue<Cat>();
p1.offer(6);
p1.offer(0);
p1.offer(8);
p1.offer(7);
p1.offer(-2);

p0.offer(6);
p0.offer(0);
p0.offer(8);
p0.offer(7);
p0.offer(-2);

System.out.println(p0.poll());

System.out.println(p1.poll());
}
}