Java Question Implementation code of abstract method

public abstract int configure(int var1, int var2, int var3);

public abstract class Maths {

    public abstract int addition(int x, int y);
    public abstract int subtraction(int x, int y);
    public abstract int multiplication(int x, int y);
    public abstract void saySomething();

}

@BA.Events(values = {"OnAddition(x as int, y as int) as int", "OnSaySomething()",
        "OnSubtraction(x as int, y as int) as int", "OnMultiplication(x as int, y as int) as int"})
@BA.ShortName("MathsWrapper")
public class MathsWrapper extends AbsObjectWrapper<Maths> {

    private BA ba;
    private String eventName;
    private Maths mat;

    public void Initialize(final BA ba, String EventName) {
        this.ba = ba;
        this.eventName = EventName;
        mat = new Maths() {
            @Override
            public int addition(int x, int y) {
                Integer result =  (Integer) ba.raiseEvent2(MathsWrapper.this,false,eventName+"_onaddition",false,x,y);
                if (result == null)
                    return -1;
                return result;
            }

            @Override
            public int subtraction(int x, int y) {
                BA.Log("in subtraction method");
                return 0;
            }

            @Override
            public int multiplication(int x, int y) {
                BA.Log("in multiplication method");
                return 0;
            }

            @Override
            public void saySomething() {
                BA.Log("in saysomething method");
                ba.raiseEvent(MathsWrapper.this,eventName+"_onsaysomething", new Object[]{});
            }
        };
        setObject(mat);
    }


    @BA.RaisesSynchronousEvents
    public void SaySomething(){
        mat.saySomething();
    }

    @BA.RaisesSynchronousEvents
    public int Addition(int x, int y){
        return mat.addition(x, y);
    }

}

Starter.ptMath.Initialize("ptm")
Dim result as Int = Starter.ptMath.Addition(50,40) 'edited
Log(result)

'B4A-events
Sub ptm_OnSaySomething()
    Log("mysaysomething")
End Sub

Sub ptm_OnAddition(x As Int, y As Int) As Int
     return MyAdditionMethod(x,y) 'edited
End Sub

Sub MyAdditionMethod(x As Int, y As Int) as Int 'edited
    Dim z As Int = x + y
    Log("This is the result " & z)
    return z
End Sub