Comparable java.lang 内比较器
传入一个对象,与自身进行比较,返回差值 正整数 0 负整数。
实现接口 :public interface Comparable<T>
接口定义的方法:public int compareto(T o);
举例:
private static class Student implements Comparable{ int id; private Student(int id){ this.id = id; } @Override public int compareto(Object o) { return this.id - ((Student)o).id; } } public void studentCompareto(){ Student s1 = new Student(10); Student s2 = new Student(20); int b = s1.compareto(s2); System.out.println(String.valueOf(b)); }
Comparator java.util 外比较器
传入两个对象,进行比较
实现接口:public interface Comparator<T>
接口定义的方法 int compare(T o1,T o2);
举例
private static class StudentCom1 implements Comparator<Student> { @Override public int compare(Student o1,Student o2) { return o1.id - o2.id; } } public void studentCompatator() { List<Student> students = new ArrayList<>(); Student student1 = new Student(10); students.add(student1); Student student2 = new Student(20); students.add(student2); Student student3 = new Student(15); students.add(student3); Collections.sort(students,new StudentCom1()); for (Student student : students) System.out.println(student.id); }
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