TextWatch does not update as it should

Good, I am trying to make a dynamic textview, one that receives data from a database, the other that shows the result of the operation of the first textview less what is being entered by the edittext, however I can not do that Show yourself how you should.

Here is the code:

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pago_correo);
        saldoUsrAct = (TextView)findViewById(R.id.saldoact);
        saldototal = (TextView)findViewById(R.id.STotal);
        monto = (EditText)findViewById(R.id.transmonto);
        correodest = (EditText)findViewById(R.id.transcorreo);
        concepto = (EditText)findViewById(R.id.transconcepto);
        aceptar = (Button)findViewById(R.id.btn_enviar);
        cancelar = (Button)findViewById(R.id.btn_cancelar);




        saldito = new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {


            }

            @Override
            public void afterTextChanged(Editable s) {
                saldototal.setText(addNumbers());
            }
        };



        saldototal.addTextChangedListener(saldito);


    }

    private String addNumbers() {
        int number1;
        int number2;
        if(saldoUsrAct.getText().toString() != "" && saldoUsrAct.getText().length() > 0) {
            number1 = Integer.parseInt(saldoUsrAct.getText().toString());
        } else {
            number1 = 0;
        }
        if(monto.getText().toString() != "" && monto.getText().length() > 0) {
            number2 = Integer.parseInt(monto.getText().toString());
        } else {
            number2 = 0;
        }

        return Integer.toString(number1 - number2);
    }

}

Thanks in advance