How to limit the EditText input only allow 3 digits of number either integer or decimal

Question

As the title says, I set up an EditText in my activity and want to limit the input to only numbers. However, it doesn't matter if it is a decimal number or integer. I do require the number of digits is limited at 3. For example, the input of '123', '1.23', '12.3' are all legit input.

'1234', '123.', '.123' are all illegal input.

I have tried to set up

android:inputType = "numberDecimal"

in the xml file.

And set the max length to 4.

edit:

I also tried following code:

InputFilter filter = new InputFilter() {

    //^\-?(\d{0,5}|\d{0,5}\.\d{0,3})$
    //^\-?(\d{0,3}|\d{0,2}\.\d{0,1}|\d{0,1}\.\d{0,2})$
    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        if (end > start) {
            // adding: filter
            // build the resulting text
            String destinationString = dest.toString();
            String resultingTxt = destinationString.substring(0, dstart) + source.subSequence(start, end) + destinationString.substring(dend);
            // return null to accept the input or empty to reject it
            return resultingTxt.matches("^\\-?(\\d{0,3}|\\d{0,2}\\.\\d{0,1}|\\d{0,1}\\.\\d{0,2})$") ? null : "";
        }

        return null;
    }
};

I did modified the regex from the sample code mentioned by @Suman Dash. My understanding of the regex

^\-?(\d{0,3}|\d{0,2}\.\d{0,1}|\d{0,1}\.\d{0,2})$

is to allow certain pattern of number input such as #.##, ##.# and ###. When I test the code, the pattern #.## and ##.# are working fine, but the pattern ### also allow input like ".##", for example, ".88" as legit input. And it treats the decimal point as a legit number, so I can only input ".88", not ".123". Anyway, I don't want any number starts with the decimal point. How can I eliminate that? What's the best way to achieve this goal? Thanks!

With statements as `android:inputType = "numberDecimal" ` your android mobile or your virtual AVD will only allow you to enter data that accomplish with your requirements set on your xml file. If you want to do more complex validations you should get the Text from your editText with `.getText().trim()` and apply your validations. — CristianoDeVinni, Sep 07 '19 at 04:36
Please take a look at here. It seems almost same problem. https://stackoverflow.com/questions/27077507/android-how-to-only-allow-a-certain-number-of-decimal-places/27077762#27077762 — Suman Kumar Dash, Sep 07 '19 at 04:50

score 0 · Answer 1 · answered Sep 07 '19 at 04:49

InputFilter filter = new InputFilter() {
    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        for (int i = start; i < end; ++i)
        {
            if (!Pattern.compile("[1234567890\.]*").matcher(String.valueOf(source.charAt(i))).matches())
            {
                return "";
            }
        }
        return null;
    }
};
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    EditText ntxt =(EditText)findViewById(R.id.numberEditTextbox) ;
    ntxt.setFilters(new InputFilter[]{filter,new InputFilter.LengthFilter(4)});

}

This code may help you.

How to limit the EditText input only allow 3 digits of number either integer or decimal

1 Answers1