类的继承和接口

class Grandparent {

    public Grandparent() {
        System.out.println("GrandParent Created.");
    }

    public Grandparent(String string) {
        System.out.println("GrandParent Created.String:" + string);
    }
}

class Parent extends Grandparent {

    public Parent() {
        super("Hello.Grandparent.");
        System.out.println("Parent Created");
       //super("Hello.Grandparent.");
    }
}

class Child extends Parent {

    public Child() {
        System.out.println("Child Created");
    }
}

public class TestInherits {

    public static void main(String args[]) {
        Child c = new Child();
       
    }
}

public final class Address
{
    private final String detail;
    private final String postCode;

    //在构造方法里初始化两个实例属性
    public Address()
    {
        this.detail = "";
        this.postCode = "";

    }
    public Address(String detail , String postCode)
    {
        this.detail = detail;
        this.postCode = postCode;
    }
    //仅为两个实例属性提供getter方法
    public String getDetail()
    {
         return this.detail;
    }

    public String getPostCode()
    {
         return this.postCode;
    }
    //重写equals方法，判断两个对象是否相等。
    public boolean equals(Object obj)
    {
        if (obj instanceof Address)
        {
            Address ad = (Address)obj;
            if (this.getDetail().equals(ad.getDetail()) && this.getPostCode().equals(ad.getPostCode()))
            {
                return true;
            }
        }
        return false;
    }
    public int hashCode()
    {
        return detail.hashCode() + postCode.hashCode();
    }
}