Android : app crashing when ever i remove number digits.(contents in text field) in android

Hi there I am working on a requirement, I have two edit text(text fields) if I enter 1 in the first text field it will increment and display 2 in the second text field.

I am getting the functionality but the problem is when ever I enter a digit and try to remove it by pressing back space its crashing.

I want to set zero when everything is removed from the first text box.

This is the code.

My xml code.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:padding="20dp" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Input Text" />

<EditText
    android:id="@+id/myTextBox"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="numberSigned" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="After Calculation" />

<EditText
    android:id="@+id/outputBox"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="numberSigned" />

My java code.

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.type2);
    final EditText outputTextBox = (EditText) findViewById(R.id.outputBox);
    final EditText myTextBox = (EditText) findViewById(R.id.myTextBox);
    myTextBox.addTextChangedListener(new TextWatcher() {

        public void afterTextChanged(Editable s) {
        }

        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

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

            String inputs = myTextBox.getText().toString();
            int i = Integer.parseInt(inputs);
            i++;
            outputTextBox.setText(String.valueOf(i));
        }
    });
}