自定义键值,要重写HashCode()
与equals
import java.util.Objects;
public class Person {
private String name;
private int age;
public Person() {
}
public Person(String name, int age) {
this.name = name;
this.age = 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 String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Person person = (Person) o;
return age == person.age &&
Objects.equals(name, person.name);
}
@Override
public int hashCode() {
return Objects.hash(name, age);
}
}
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
public class DemoKey {
public static void main(String[] args) {
Map<Person,String> map =new HashMap<>();
map.put(new Person("1hao",12),"meiguo");
map.put(new Person("2hao",15),"riben");
map.put(new Person("3hao",13),"zhongguo");
map.put(new Person("1hao",12),"meiguo");
System.out.println(map);
}
}