add method dynamically on start of application

I have a class with a method having custom annotation

@Target(ElementType.METHOD)
public @interface MethodXY {
    public int x();
    public int y();
}

public class AnnotationTest {
    @MethodXY(x=5, y=5)
    public void myMethodA(){ ... }

    @MethodXY(x=3, y=2)
    public void myMethodB(){ ... }
}

I want to add N number of methods in this class at run time once when the class loads. The values of X & Y will be read from an array of size N ( any collection / properties file )

I am able to change values of annotation at run time

MethodXY anno2 = (MethodXY) setAttrValue(anno, MethodXY.class, "x", "400");
System.out.println(String.format("New values: %s, %s",  anno2.X(), anno2.y()));

but unable to pass new annotation value to method .

How could it be done in java .