CODEWITHSUNDEEP
javaandroidandroid-edittextnumberformatexception
REAL O G
REAL O G

Reputation: 685

EditText for input and output

I'm new to SO and a fairly new to Java so please don't hate on me. I have multiple editText boxes that are supposed to function like an excel spreadsheet. Here is some code from this simple application: 

EditText tradeDif = (EditText) findViewById(R.id.tradeDif);    

TextWatcher tradeWatch = new TextWatcher() {

    @Override
    public void afterTextChanged(Editable s) {
        calcTrade();

    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before,
            int count) {
        // TODO Auto-generated method stub

    }

};

private void calcTrade() throws NumberFormatException {
Editable eValue1 = newPrice.getText(), eValue2 = tradeIn.getText(), eValue3 = acc.getText();
Double value1 = 0.0, value2 = 0.0, value3 = 0.0, result = 0.0;


if (eValue1 != null)
    value1 = Double.parseDouble(eValue1.toString());
if (eValue2 != null)
    value2 = Double.parseDouble(eValue2.toString());
if (eValue3 != null)
    value3 = Double.parseDouble(eValue3.toString());
if (value1 != null && value2 != null && value3 != null)
    result = value1 - (value2 + value3);
    tradeDif.setText(result.toString());

}

The EditText field TradeDif needs to be able to display the variable result. When I run this it crashes, and I THINK it's because the tradeDif editText is empty. Also, I need to be able to use what is displayed in the tradeDif EditText for further calculations with further editTexts. I'm assuming I would need to use some kind of try catch block, but I'm kind of unsure how to implement it. Any help is appreciated.

Upvotes: 0

Views: 83

Answers (2)

Tom
Tom

Reputation: 17567

Double.parseDouble() throws a NumberFormatException if the provided String does not contain a valid double value. This includes empty String.

To pass that error, I suggest to check, if the string is empty by creating a new method:

private double toDouble(final Editable editable) {
    final String content = editable.toString();
    if (content.isEmpty()) {
        return 0;
    }
    return Double.parseDouble(content);
}

And then change your code to:

if (eValue1 != null)
    value1 = toDouble(eValue1);
if (eValue2 != null)
    value2 = toDouble(eValue2);
if (eValue3 != null)
    value3 = toDouble(eValue3);

The new method avoids code doubling and it could easily be maintained.

You could also think about catching the Exception, but I prefer avoiding them in the first place. Especially for this kind of reason (empty String).

Upvotes: 1

Dan Osipov
Dan Osipov

Reputation: 1431

Surround your if statements with a try/catch, and handle failure appropriately:

try {
    if (eValue1 != null)
        value1 = Double.parseDouble(eValue1.toString());
    if (eValue2 != null)
        value2 = Double.parseDouble(eValue2.toString());
    if (eValue3 != null)
        value3 = Double.parseDouble(eValue3.toString());
    if (value1 != null && value2 != null && value3 != null)
        result = value1 - (value2 + value3);
        tradeDif.setText(result.toString());
} catch (NumberFormatException e) {
    // Not a number in one of the fields, alert user
}

Upvotes: 1

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