Automatic sum of two Edittext to put result in a Textview

Question

I want to take two values out of two EditText and put the result of these two values into one TextView. I made that code but this giving error

editPecaBoas = findViewById(R.id.editPecaBoas);

editPecaRuins = findViewById(R.id.editPecaRuins);


public void sumParts() {

    TextWatcher watcher = 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) {
            int a = Integer.parseInt(editPecaBoas.getText().toString());
            int b = Integer.parseInt(editPecaRuins.getText().toString());

            int i = a + b;

            String t = String.valueOf(i);

            textViewResult.setText(t);
        }
    };

That is the mistake

java.lang.NumberFormatException: For input string: ""

Answer 1

The mentioned error occurs because you are trying to convert a String empty in a int, you can add a validation, for case the one of EditText is empty consider the value 0. Example:

@Override
public void afterTextChanged(Editable s) {

    String valueStrEditPecaBoas = editPecaBoas.getText().toString();
    String valueStrEditPecaRuins = editPecaRuins.getText().toString();

    int pecasBoas, pecasRuins;

    if(TextUtils.isEmpty(valueStrEditPecaBoas)) {
        pecasBoas = 0;
        editPecaBoas.setText("0");
    } else {
        pecasBoas = Integer.parseInt(valueStrEditPecaBoas);
    }

    if(TextUtils.isEmpty(valueStrEditPecaRuins)) {
        pecasRuins = 0;
        editPecaRuins.setText("0");
    } else {
        pecasRuins = Integer.parseInt(valueStrEditPecaRuins);
    }

    textViewResult.setText(String.valueOf(pecasBoas + pecasRuins));
}

In this example I also made a setText("0") to have a visual return in the field, but it is not necessary to resolve your error.