ArrayList to String Without the spaces in Android Studio

I am trying to convert this

ArrayList<String> arrayList = new ArrayList<String>();



String NumberRightString = "";

String ButtonText = "";



public void OnClick (View v) {



    Button button = (Button) v;



    String ButtonText = button.getText().toString();



    arrayList.add(ButtonText);



    StringBuilder sb = new StringBuilder();



    for (Object obj : arrayList) {

        sb.append(obj.toString());

        sb.append("\t");

    }



    String NumString = sb.toString();



    NumString.replaceAll("//s","");



    textView.setText(NumString + "/" + number);

}