Erro on use programmatically

[d3roch4]

code:
NumberPicker numberPicker = new NumberPicker(opcionais.getContext());
numberPicker.setValue(itens.get(i).quantidade);

Error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
at com.travijuu.numberpicker.library.NumberPicker.refresh(NumberPicker.java:113)
at com.travijuu.numberpicker.library.NumberPicker.setValue(NumberPicker.java:155)