content: package class06;
  
  import java.util.Comparator;
  import java.util.PriorityQueue;
  
  public class ShowComparator2 {
  
  	public static class MyComparator implements Comparator<Integer> {
  
  		// 负，第一个参数在前
  		// 正，第二个参数在前
  		// 0, 谁放前都行
  		@Override
  		public int compare(Integer o1, Integer o2) {
  			if (o1 < o2) {
  				return 1;
  			} else if (o1 > o2) {
  				return -1;
  			} else {
  				return 0;
  			}
  		}
  
  	}
  
  	public static class Student {
  		public String name;
  		public int id;
  		public int age;
  
  		public Student(String name, int id, int age) {
  			this.name = name;
  			this.id = id;
  			this.age = age;
  		}
  	}
  
  	// 谁id大，谁放前！
  	public static class IdComparator implements Comparator<Student> {
  
  		// 如果返回负数，认为第一个参数应该排在前面
  		// 如果返回正数，认为第二个参数应该排在前面
  		// 如果返回0，认为谁放前面无所谓
  		@Override
  		public int compare(Student o1, Student o2) {
  			if (o1.id < o2.id) {
  				return 1;
  			} else if (o2.id < o1.id) {
  				return -1;
  			} else {
  				return 0;
  			}
  		}
  	}
  
  	public static void main(String[] args) {
  		String str1 = "abc";
  		String str2 = "b";
  		System.out.println(str1.compareTo(str2));
  		PriorityQueue<Student> heap = new PriorityQueue<>(new IdComparator());
  		Student s1 = new Student("张三", 5, 27);
  		Student s2 = new Student("李四", 1, 17);
  		Student s3 = new Student("王五", 4, 29);
  		Student s4 = new Student("赵六", 3, 9);
  		Student s5 = new Student("左七", 2, 34);
  		heap.add(s1);
  		heap.add(s2);
  		heap.add(s3);
  		heap.add(s4);
  		heap.add(s5);
  		System.out.println("=========");
  		while (!heap.isEmpty()) {
  			Student s = heap.poll();
  			System.out.println(s.name + ", " + s.id + ", " + s.age);
  		}
  	}
  
  }
  