i_correct.java

public interface OnClickListener { 
    void onClick(View v);
}
public interface OnLongClickListener { 
    void onLongClick(View v);
}
public interface OnTouchListener { 
    void onTouch(View v, MotionEvent event);
}

valid.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                // TODO: 
            }
});