class OnClickConverter implements View.OnFocusChangeListener {
    Runnable onClickAction;

    public OnClickConverter(Runnable onClickAction) {
        this.onClickAction = onClickAction;
    }

    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if (hasFocus) {
            Button buttonConvertSpeed = (Button) rootView.findViewById(R.id.buttonConvertSpeed);
            buttonConvertSpeed.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    onClickAction.run();
                }
            });
        }
    }
}

...

editKnot.setOnFocusChangeListener(new OnClickConverter(new Runnable() {
    @Override
    public void run() {
        // Custom logic goes here.
    }
});