public class HelloWorld{

     public static void main(String []args){
        A a = new A();
        B b = new B();
        check(a, b);
     }

     private static void check(A a, B b){
        if ( ( a.getX() != b.getY() && (a.getX() == null || b.getY() == null) )
             || ( a.getX() != null && !a.getX().equals(b.getY()) ) ) {
            System.out.println("IN");
        }
     }
}

class A{
    String x = "1";
    public String getX(){
        return this.x;
    }
}
class B{
    String y = "2";
    public String getY(){
        return this.y;
    }
}

// What I want to achieve:
// pcs = null && mp = null -> skip
// pcs = "1" && mp = "1" -> skip
// pcs = null && mp = "1" -> enter
// pcs = "1" && mp = null -> enter
// pcs = "1" && mp = "2" -> enter