Java 继承的综合练习_public class employee extends object{ int id; stri-优快云博客

这篇博客探讨了Java中对象的相等性检查，通过`equals()`和`hashCode()`方法的实现。示例展示了如何在`Employee`类中正确覆盖`equals()`方法以基于ID进行比较。此外，还涉及了子类`Child`对父类`Parent`的继承，并展示了构造函数的调用顺序以及成员变量的访问和覆盖。



import java.util.Objects;

public class TestObject {

    public static void main(String[] args) {
        Employee e1 = new Employee(1001,"张三");
        Employee e2 = new Employee(1001,"张三");

        System.out.println(e1);
        System.out.println(e1==e2);
        System.out.println(e1.equals(e2));
    }
}
    class Employee extends Object{
    int id;
    String name;

    public Employee(int id,String name){
        this.id = id;
        this.name = name;
    }
    public String toString(){
        return "雇员编号："+id+"，姓名："+name;
    }
    public boolean equals(Object o){
        if (this==o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Employee employee = (Employee) o;
        return id == employee.id;
    }
        public int hashCode() {
            return Objects.hash(id);
        }

    }


```java
public class TestSuper {
    public static void main(String[] args) {
        Child c = new Child();
        c.show();
    }
}

class Parent {
    int num = 300;

    public void show(){
        System.out.println("父类中，show()");
    }

    public Parent(){
//        super();
        System.out.println("初始化父类对象！");
    }
}

class Child extends Parent{
    int  num = 1000;

    public Child(){
        super();
        System.out.println("初始化子类对象！");
    }

    @Override
    public void show() {
        System.out.println("子类中，show()");
        super.show();
        System.out.println("子类中，num："+num);
        System.out.println("父类的num："+super.num);
    }
}