maxLength property

int maxLength

The maximum number of characters (Unicode scalar values) to allow in the text field.

If set, a character counter will be displayed below the field showing how many characters have been entered. If set to a number greater than 0, it will also display the maximum number allowed. If set to TextField.noMaxLength then only the current character count is displayed.

After maxLength characters have been input, additional input is ignored, unless maxLengthEnforced is set to false. The text field enforces the length with a LengthLimitingTextInputFormatter, which is evaluated after the supplied inputFormatters, if any.

This value must be either null, TextField.noMaxLength, or greater than 0. If null (the default) then there is no limit to the number of characters that can be entered. If set to TextField.noMaxLength, then no limit will be enforced, but the number of characters entered will still be displayed.

Whitespace characters (e.g. newline, space, tab) are included in the character count.

If maxLengthEnforced is set to false, then more than maxLength characters may be entered, but the error counter and divider will switch to the decoration.errorStyle when the limit is exceeded.


The text field does not currently count Unicode grapheme clusters (i.e. characters visible to the user), it counts Unicode scalar values, which leaves out a number of useful possible characters (like many emoji and composed characters), so this will be inaccurate in the presence of those characters. If you expect to encounter these kinds of characters, be generous in the maxLength used.

For instance, the character "ö" can be represented as '\u{006F}\u{0308}', which is the letter "o" followed by a composed diaeresis "¨", or it can be represented as '\u{00F6}', which is the Unicode scalar value "LATIN SMALL LETTER O WITH DIAERESIS". In the first case, the text field will count two characters, and the second case will be counted as one character, even though the user can see no difference in the input.

Similarly, some emoji are represented by multiple scalar values. The Unicode "THUMBS UP SIGN + MEDIUM SKIN TONE MODIFIER", "👍🏽", should be counted as a single character, but because it is a combination of two Unicode scalar values, '\u{1F44D}\u{1F3FD}', it is counted as two characters.

See also:


final int maxLength