List中的Contains方法内部其实是用对象的equals方法做比较，所以如果比较两个类就重写类的equals方法即可；而Set是调用equals和hashCode

public class Person {

    private String name;
    private int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public boolean equals(Object obj) {
        Person person = (Person) obj;
        return this.name == person.getName();
    }

//    @Override
//    public int hashCode() {
//        return 1;
//    }
}

 

 

public class TestDemo {

    @Test
    public void func1(){
        Person person=new Person();
        person.setName("aaa");
        person.setAge(20);

        Person person1=new Person();
        person1.setName("aaa");
        person1.setAge(22);

        List<Person> personList=new ArrayList<Person>();
        personList.add(person);
        if(!personList.contains(person1)){
            personList.add(person1);
        }
        Set<Person> personSet=new HashSet<Person>();
        personSet.add(person);
        if(!personSet.contains(person1)){
            personSet.add(person1);
        }

        System.out.println("");

    }

}

 

打开Person类的hasCode注释后，运行如下