libgdx - How to force subclass to implement some methods in java? -

i have screen interface in libgdx framework.

i create subclass called baselayout, initialize fields.

now every actual screen e.g. menuscreen extend baselayout class.

i want force these classes e.g. menuscreen implement 2 methods void initdata(), , void addbuttonstoscreen(). how this?

i call these methods in show method implemented in base class baselayout.

i want force these classes e.g. menuscreen implement 2 methods void initdata(), , void addbuttonstoscreen(). how this?

make baselayout abtract class , make initdata() , addbuttonstoscreen() abstract methods.

example

public abstract class baselayout extends screen {      public void initdata();      public void addbuttonstoscreen(); } 

then make subclasses extend , implement methods..

public class concretelayout extends baselayout {      public void initdata()      {          // code here.      }       public void addbuttonstoscreen()      {          // code here.      } }