How do I use InputFilter to limit characters in an EditText in Android

Question

I want to restrict the chars to 0-9  a-z  A-Z and spacebar only   Setting inputtype I can limit to digits but I cannot figure out the ways of Inputfilter looking through the docs

User · Answer

I have done something like this to keep it simple:

edit_text.filters = arrayOf(object : InputFilter {
    override fun filter(
        source: CharSequence?,
        start: Int,
        end: Int,
        dest: Spanned?,
        dstart: Int,
        dend: Int
    ): CharSequence? {
        return source?.subSequence(start, end)
            ?.replace(Regex("[^A-Za-z0-9 ]"), "")
    }
})

This way we are replacing all the unwanted characters in the new part of the source string with an empty string.

The edit_text variable is the EditText object we are referring to.

The code is written in kotlin.

User · Answer

to prevent words in edittext  create a class that u could use anytime   public class Wordfilter implements InputFilter        Override     public CharSequence filter CharSequence source  int start  int end Spanned dest  int dstart  int dend               TODO Auto-generated method stub         boolean append   false          String text   source toString   substring start  end           StringBuilder str   new StringBuilder dest toString             if dstart    str length                          append   true              str append text                     else             str replace dstart  dend  text           if str toString   contains  aaaaaaaaaaaa  the word here  aaaaaaaa                          if append  true                  return                 else                 return dest subSequence dstart  dend                     return null

User · Answer

To avoid Special Characters in input type  public static InputFilter filter   new InputFilter          Override     public CharSequence filter CharSequence source  int start  int end  Spanned dest  int dstart  int dend            String blockCharacterSet                -                      lt  gt                                                      -  -  -D -     O 1234567890           if  source    null  amp  amp  blockCharacterSet contains       source                  return                       return null             You can set filter to your edit text like below  edtText setFilters new InputFilter     filter

User · Answer

You can specify wanted characters in a regex and use it in InputFilter  val regex   Regex  quot  a-zA-Z  d   quot        editText filters   arrayOf InputFilter   source                - gt      source filter   regex matches it toString          Notice  I didn t used  w character class  because it includes underscore

User · Answer

First add into strings xml    lt string name  vin code mask  gt 0123456789abcdefghjklmnprstuvwxyz lt  string gt    XML   android digits   string vin code mask    Code in Kotlin   edit text filters    InputFilter   source  start  end          - gt      val mask   getString R string vin code mask      for  i in start until end            if   mask contains source i                  return InputFilter                        null     Strange  but it works weirdly on emulator s soft keyboard   Warning  The following code will filter all letters and other symbols except digits for software keyboards  Only digital keyboard will appear on smartphones   edit text keyListener   DigitsKeyListener getInstance context getString R string vin code mask     I also usually set maxLength  filters  inputType

User · Answer

For some reason the android text LoginFilter class s constructor is package-scoped  so you can t directly extend it  even though it would be identical to this code    But you can extend LoginFilter UsernameFilterGeneric   Then you just have this   class ABCFilter extends LoginFilter UsernameFilterGeneric       public UsernameFilter             super false      false prevents not-allowed characters from being appended             Override     public boolean isAllowed char c            if   A   lt   c  amp  amp  c  lt    C               return true          if   a   lt   c  amp  amp  c  lt    c               return true           return false            This isn t really documented  but it s part of the core lib  and the source is straightforward   I ve been using it for a while now  so far no problems  though I admit I haven t tried doing anything complex involving spannables

User · Answer

InputFilters are a little complicated in Android versions that display dictionary suggestions  You sometimes get a SpannableStringBuilder  sometimes a plain String in the source parameter   The following InputFilter should work  Feel free to improve this code   new InputFilter          Override     public CharSequence filter CharSequence source  int start  int end              Spanned dest  int dstart  int dend             if  source instanceof SpannableStringBuilder                SpannableStringBuilder sourceAsSpannableBuilder    SpannableStringBuilder source              for  int i   end - 1  i  gt   start  i--                     char currentChar   source charAt i                    if   Character isLetterOrDigit currentChar   amp  amp   Character isSpaceChar currentChar                              sourceAsSpannableBuilder delete i  i 1                                                     return source            else               StringBuilder filteredStringBuilder   new StringBuilder                for  int i   start  i  lt  end  i                       char currentChar   source charAt i                   if  Character isLetterOrDigit currentChar     Character isSpaceChar currentChar                             filteredStringBuilder append currentChar                                                    return filteredStringBuilder toString

User · Answer

If you subclass InputFilter you can create your own InputFilter that would filter out any non-alpha-numeric characters     The InputFilter Interface has one method  filter CharSequence source  int start  int end  Spanned dest  int dstart  int dend   and it provides you with all the information you need to know about which characters were entered into the EditText it is assigned to   Once you have created your own InputFilter  you can assign it to the EditText by calling setFilters        http   developer android com reference android text InputFilter html filter java lang CharSequence  int  int  android text Spanned  int  int

User · Answer

I found this on another forum   Works like a champ   InputFilter filter   new InputFilter         public CharSequence filter CharSequence source  int start  int end              Spanned dest  int dstart  int dend            for  int i   start  i  lt  end  i                  if   Character isLetterOrDigit source charAt i                      return                                     return null           edit setFilters new InputFilter     filter

User · Answer

It s Right  the best way to go about it to fix it in the XML Layout itself using    lt EditText android inputType  text  android digits  0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ    gt    as rightly pointed by Florian Fr  hlich  it works well for text views even    lt TextView android inputType  text  android digits  0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ    gt    Just a word of caution  the characters mentioned in the android digits will only be displayed  so just be careful not to miss any set of characters out

User · Answer

In addition to the accepted answer  it is also possible to use e g   android inputType  textCapCharacters  as an attribute of  lt EditText gt  in order to only accept upper case characters  and numbers

User · Answer

This simple solution worked for me when I needed to prevent the user from entering empty strings into an EditText   You can of course add more characters   InputFilter textFilter   new InputFilter       Override  public CharSequence filter CharSequence c  int arg1  int arg2       Spanned arg3  int arg4  int arg5         StringBuilder sbText   new StringBuilder c        String text   sbText toString         if  text contains                     return                      return c                  private void setTextFilter EditText editText         editText setFilters new InputFilter   textFilter

User · Answer

I have the same answer in Kotlin          Returns the filter of the editText es CharSequence value when  filterType  is     1 - gt  letters  2 - gt  letters and digits  3 - gt  digits     4 - gt  digits and dots     class InputFilterAlphanumeric private val filterType  Int   InputFilter       override fun filter source  CharSequence   start  Int  end  Int  dest  Spanned   dstart  Int  dend  Int   CharSequence            source as  SpannableStringBuilder   let  sourceAsSpannableBuilder  - gt              for  i in  end - 1  downTo start                    val currentChar   source i                  when filterType                        1 - gt                            if   currentChar isLetter    amp  amp   currentChar isWhitespace                                  sourceAsSpannableBuilder delete i  i   1                                                                      2 - gt                            if   currentChar isLetterOrDigit    amp  amp   currentChar isWhitespace                                  sourceAsSpannableBuilder delete i  i   1                                                                      3 - gt                            if   currentChar isDigit                                  sourceAsSpannableBuilder delete i  i   1                                                                      4 - gt                            if   currentChar isDigit       currentChar toString   contains                                     sourceAsSpannableBuilder delete i  i   1                                                                                              return source              run               val filteredStringBuilder   StringBuilder               for  i in start until end                    val currentChar   source  get i                  when filterType                        1 - gt                            if  currentChar  isLetter        currentChar isWhitespace                                  filteredStringBuilder append currentChar                                                                      2 - gt                            if  currentChar  isLetterOrDigit        currentChar isWhitespace                                  filteredStringBuilder append currentChar                                                                      3 - gt                            if  currentChar  isDigit                                    filteredStringBuilder append currentChar                                                                      4 - gt                            if  currentChar  isDigit        currentChar toString   contains                                     filteredStringBuilder append currentChar                                                                                              return filteredStringBuilder                     and get the class with an Extension function   fun EditText filterByDataType filterType  Int        this filters   arrayOf lt InputFilter gt  InputFilterAlphanumeric filterType

User · Answer

Ignoring the span stuff that other people have dealt with  to properly handle dictionary suggestions I found the following code works    The source grows as the suggestion grows so we have to look at how many characters it s actually expecting us to replace before we return anything    If we don t have any invalid characters  return null so that the default replacement occurs    Otherwise we need to extract out the valid characters from the substring that s ACTUALLY going to be placed into the EditText   InputFilter filter   new InputFilter          public CharSequence filter CharSequence source  int start  int end       Spanned dest  int dstart  int dend              boolean includesInvalidCharacter   false          StringBuilder stringBuilder   new StringBuilder             int destLength   dend - dstart   1          int adjustStart   source length   - destLength          for int i start   i lt end   i                  char sourceChar   source charAt i               if Character isLetterOrDigit sourceChar                     if i  gt   adjustStart                       stringBuilder append sourceChar                 else                 includesInvalidCharacter   true                    return includesInvalidCharacter   stringBuilder   null

User · Answer

It is possible to use setOnKeyListener  In this method  we can customize the input edittext

User · Answer

This is how I created filter for the Name field in Edit Text  First letter is CAPS  and allow only single space after every word      public void setNameFilter         InputFilter filter   new InputFilter              RequiresApi api   Build VERSION CODES KITKAT          public CharSequence filter CharSequence source  int start  int end                                     Spanned dest  int dstart  int dend                for  int i   start  i  lt  end  i                      if  dend    0                        if  Character isSpaceChar source charAt i                                   Character isAlphabetic source charAt i                              return Constants Delimiter BLANK                        else                           return String valueOf source charAt i   toUpperCase                                            else if  Character isSpaceChar source charAt i    amp  amp                          String valueOf dest  endsWith Constants Delimiter ONE SPACE                         return Constants Delimiter BLANK                    else if    Character isSpaceChar source charAt i    amp  amp                           Character isAlphabetic source charAt i                           return Constants Delimiter BLANK                                              return null                       editText setFilters new InputFilter   filter  new InputFilter LengthFilter Constants Length NAME LENGTH

User · Answer

much easier    lt EditText     android inputType  text      android digits  0 1 2 3 4 5 6 7 8 9   qwertzuiopasdfghjklyxcvbnm    gt

User · Answer

None of posted answers did work for me  I came with my own solution   InputFilter filter   new InputFilter          Override     public CharSequence filter CharSequence source  int start  int end  Spanned dest  int dstart  int dend            boolean keepOriginal   true          StringBuilder sb   new StringBuilder end - start           for  int i   start  i  lt  end  i                  char c   source charAt i               if  isCharAllowed c      put your condition here                 sb append c               else                 keepOriginal   false                    if  keepOriginal              return null          else               if  source instanceof Spanned                    SpannableString sp   new SpannableString sb                   TextUtils copySpansFrom  Spanned  source  start  sb length    null  sp  0                   return sp                else                   return sb                                                private boolean isCharAllowed char c            return Character isLetterOrDigit c     Character isSpaceChar c           editText setFilters new InputFilter     filter

User · Answer

This is an old thread  but the purposed solutions all have issues  depending on device   Android version   Keyboard    DIFFERENT APPROACH  So eventually I went with a different approach  instead of using the InputFilter problematic implementation  I am using TextWatcher and the TextChangedListener of the EditText   FULL CODE  EXAMPLE   editText addTextChangedListener new TextWatcher           Override     public void afterTextChanged Editable editable            super afterTextChanged editable            String originalText   editable toString            int originalTextLength   originalText length            int currentSelection   editText getSelectionStart                Create the filtered text         StringBuilder sb   new StringBuilder            boolean hasChanged   false          for  int i   0  i  lt  originalTextLength  i                  char currentChar   originalText charAt i               if  isAllowed currentChar                     sb append currentChar                 else                   hasChanged   true                  if  currentSelection  gt   i                        currentSelection--                                                        If we filtered something  update the text and the cursor location         if  hasChanged                String newText   sb toString                editText setText newText               editText setSelection currentSelection                        private boolean isAllowed char c               TODO  Add the filter logic here         return Character isLetter c     Character isSpaceChar c              Override     public void beforeTextChanged CharSequence s  int start  int count  int after               Do Nothing             Override     public void onTextChanged CharSequence s  int start  int before  int count               Do Nothing             The reason InputFilter is not a good solution in Android is since it depends on the keyboard implementation  The Keyboard input is being filtered before the input is passed to the EditText  But  because some keyboards have different implementations for the InputFilter filter   invocation  this is problematic   On the other hand TextWatcher does not care about the keyboard implementation  it allows us to create a simple solution and be sure it will work on all devices

User · Answer

Use this its work 100  your need and very simple    lt EditText android inputType  textFilter  android digits   string myAlphaNumeric    gt    In strings xml   lt string name  myAlphaNumeric  gt abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 lt  string gt

[android] How do I use InputFilter to limit characters in an EditText in Android?

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