How to validate user input in Android?

Question

I have a simple EditText where a user can insert three values separated by commas. For instance, I can have the following template:

value1, value2, value3

where value1, value2 are of double type and value3 is integer.

How can I validate that the user has entered a text according to this template?

Yury · Accepted Answer · 2012-07-08 19:46:22Z

4

Use a regex Matcher.

final String DOUBLE = "\\d+(?:\\.\\d+)?";
final Pattern PATTERN = Pattern.compile(DOUBLE + ", " + DOUBLE + ", \\d+");
Matcher matcher = PATTERN.matcher(textView.getText().toString());
if (!matcher.matches()) {
    // invalid input
}

edited Jul 8, 2012 at 19:46

Yury

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answered Jul 8, 2012 at 10:56

Dheeraj Vepakomma

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5 Comments

Dan S Over a year ago

Don't foreget to use the listener to catch the text changed event. [developer.android.com/reference/android/widget/…

Yury Over a year ago

I do not know why, but there should be added one correction: final String DOUBLE = "\\d+(?:\\.\\d+)?"; final Pattern Pattern = Pattern.compile(DOUBLE + ", " + DOUBLE + ", \\d+"); Can you correct and I'll accept the answer?

Dheeraj Vepakomma Over a year ago

@Yury Silly me, you're right. In a java String literal, to get a black-slash, we need to escape it. So we need two back-slashes. Corrected my answer.

Yury Over a year ago

@Dheeraj Do not worry ) I think it was a nice training how I had understood the topic! Thanks!

Dheeraj Vepakomma Over a year ago

@Yury To be more flexible, you can allow multiple spaces after the comma using , * for the separator. Also, leading & trailing spaces can be allowed by trimming the input: textView.getText().toString().trim().

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