HashSet经典面试题记录

首先有个person类实现了Comparable接口

class Person implements Comparable{

    String name;
    int age;

    public Person(String name1, int age){
        name = name1;
        this.age = age;
    }

    @Override
    public boolean equals(Object o) {
        System.out.println("equals-----------------------");
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Person person = (Person) o;
        return age == person.age && name.equals(person.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    @Override
    public int compareTo(Object o) {
        System.out.println("compare to -------------");
        if (o instanceof Person){
            Person o1 = (Person) o;
            return Integer.compare(this.age,o1.age);
        }
        throw new RuntimeException("输入类型不符合");
    }
}
re>
 
以下是测试的代码
re>
@Test
public void test3(){
    HashSet