Java将变量从超类转移到子类

Question

In java i have a class A which extends class B

I want to assign all of the contents from class B to class A thing is i want to do it from inside class A now this seems reasonable easy to do just transfer all of the variables.

This is the hard part. I didn't make class B it's a part of android.widget In c++ you would just take in class b and then assign to *this and cast it.

How would i go about doing this in java?

To further clarify it's a relativelayout i need to copy all the contents of a relativelayout into a class that extends relative layout

class something extends other
{
public something(other a){
 //transfer all of the other class into something
 this=(something)a;  // obviously doesn't work
 //*this doesn't exist?
 //too many variables to transfer manually
}
}

Thanks so much for all the help. Really appreciate it!!!

Answer 1

See the code given below . It is using java.lang.reflect package to extract out all the fields from super class and assigning the obtained value to the child class variables.

import java.lang.reflect.Field;
class Super
{
    public int a ;
    public String name;
    Super(){}
    Super(int a, String name)
    {
        this.a = a;
        this.name = name;
    }
}
class Child extends Super 
{
    public Child(Super other)
    {
        try{
        Class clazz = Super.class;
        Field[] fields = clazz.getFields();//Gives all declared public fields and inherited public fields of Super class
        for ( Field field : fields )
        {
            Class type = field.getType();
            Object obj = field.get(other);
            this.getClass().getField(field.getName()).set(this,obj);
        }
        }catch(Exception ex){ex.printStackTrace();}
    }
    public static void main(String st[])
    {
        Super ss = new Super(19,"Michael");
        Child ch = new Child(ss);
        System.out.println("ch.a="+ch.a+" , ch.name="+ch.name);
    }
}

Answer 2

父类（非私有）的所有变量和函数都是子类中的直接访问。您不需要在子类中分配任何东西。您可以直接访问。

Answer 3

This will not work:

Something something = (Something) other.clone();

if the true runtime type of other is Other .

Instead you have to create a copy constructor, or instantiate other as an instance of Something and then clone it.