java - 当我们将自定义类对象作为键和值传递时，如何根据键名称从 HashMap 获取值

Question

当我们将自定义类对象作为键和值对传递时，如何根据键名称从 HashMap 中获取值。在下面的代码中，当我使用 get 方法通过使用 key 检索值时，我正在获取编译时间错误。请帮助我解决这个问题。

HashMap<Employee1, Department1> hm= new HashMap<Employee1, Department1>();
    hm.put(new Employee1(0, "name1", 25, 46666), new Department1(0, "developer"));
    hm.put(new Employee1(0, "name2", 50, 40000), new Department1(0, "tester"));
    hm.put(new Employee1(0, "name3", 34, 3000), new Department1(0, "hr"));
    hm.put(new Employee1(0, "name4",30, 26666), new Department1(0, "manager"));
    hm.put(new Employee1(0, "name5",28, 15000), new Department1(0, "accountant"));

    Department1 value = (Department1) hm.get(0, "name5",28, 15000);
    System.out.println(value);

部门.java-

package org.task;
public class Department1 {
private int deptid;
private String deptname;

public int getDeptid() {
    return deptid;
}
   public String getDeptname() {
    return deptname;
}

public Department1(int deptid, String deptname) {
    this.deptid = deptid;
    this.deptname = deptname;

}

}

Employee.java-

package org.task;
public class Employee1 {
private int id;
private String name;
private int age;
private long salary;

public int getId() {
    return id;
}

public String getName() {
    return name;
}

public int getAge() {
    return age;
}

public long getSalary() {
    return salary;
}

public Employee1(int id, String name, int age, int salary) {
    this.id = id;
    this.name = name;
    this.age = age;
    this.salary = salary;
}
}

我想通过传递部门 ID 或部门名称来检索员工的所有详细信息

Answer 1

您必须重写 Employee 类的 equals 方法那么你可以使用

Employee1 testEmp =  new Employee1(0, "name5",28, 15000);
Department1 value = (Department1) hm.get(testEmp);
System.out.println(value);