Develop Reference

Android Alphanumeric only, programmatically (NOT XML)

I have a program in Android, with one AutoCompleteTextView named aCTVNumeroPoste.
This AutoCompleteTextView change the type of input depends of other option.
So Option 1 makes the AutoCompleteTextView only Text and Option 2 makes the AutoCompleteTextView only Numbers. And this seems to works well with the keyboard.
But THE PROBLEM is when the AutoCompleteTextView is Text, I only want Alphanumeric, and the keyboard allow me to introduce $%&/()=?¡"!-.,etc.
Heres the code:
if (accion.equals("MANTENIMIENTO")) {
aCTVNumeroPoste.setInputType(InputType.TYPE_CLASS_TEXT);
int maxLengthofEditText = 19;
aCTVNumeroPoste.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLengthofEditText)});
}
else {
aCTVNumeroPoste.setInputType(InputType.TYPE_CLASS_NUMBER);
aCTVNumeroPoste.setKeyListener(DigitsKeyListener.getInstance("0123456789"));
int maxLengthofEditText = 3;
aCTVNumeroPoste.setFilters(new InputFilter[] {new InputFilter.LengthFilter(maxLengthofEditText)});
}
And i want to resolve this Programmatically, not in XML (with android:digits=...).
I tried to use this code, after InputType.TYPE_CLASS_TEXT:
aCTVNumeroPoste.setFilters(new InputFilter[]{
new InputFilter() {
public CharSequence filter(CharSequence src, int start,
int end, Spanned dst, int dstart, int dend) {
if (src.equals("")) {
return src;
}
if (src.toString().matches("[a-zA-Z 0-9]+")) {
return src;
}
return "";
}
}
});
And this one too:
aCTVNumeroPoste.setKeyListener(DigitsKeyListener.getInstance("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 "));
But nothing has worked. Any help is appreciated.

I answer my own question.
From this post How to restrict the EditText to accept only alphanumeric characters
This code works for me:
public static class AlphaNumericInputFilter implements InputFilter {
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend) {
// Only keep characters that are alphanumeric
StringBuilder builder = new StringBuilder();
for (int i = start; i < end; i++) {
char c = source.charAt(i);
if (Character.isLetterOrDigit(c)) {
builder.append(c);
}
}
// If all characters are valid, return null, otherwise only return the filtered characters
boolean allCharactersValid = (builder.length() == end - start);
return allCharactersValid ? null : builder.toString();
}
}
And then add this after InputType.TYPE_CLASS_TEXT:
// Apply the filters to control the input (alphanumeric)
ArrayList<InputFilter> curInputFilters = new ArrayList<InputFilter>(Arrays.asList(aCTVNumeroPoste.getFilters()));
curInputFilters.add(0, new AlphaNumericInputFilter());
curInputFilters.add(1, new InputFilter.LengthFilter(maxLengthofEditText));
InputFilter[] newInputFilters = curInputFilters.toArray(new InputFilter[curInputFilters.size()]);
aCTVNumeroPoste.setFilters(newInputFilters);

EditText to restrict entering special characters: single quote, double quote and emojis

I have a problem while inserting special characters: single quote, double quote and emojis into the database from editText.
I want my editText to restrict those characters, and I was successful in restricting emojis, but I failed to restrict users entering single quote and double quote.
E.g. When I try to enter text Today's List from editText into the database it generates an exception.
I have used InputFilter in editText to filter emojis, and I want this filter to restrict single quote and double quotes too.
public static InputFilter getEditTextFilterEmoji() {
return new InputFilter() {
#Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
CharSequence sourceOriginal = source;
source = replaceEmoji(source);
end = source.toString().length();
if (end == 0)
return ""; //Return empty string if the input character is already removed
if (!sourceOriginal.toString().equals(source.toString())) {
char[] v = new char[end - start];
TextUtils.getChars(source, start, end, v, 0);
String s = new String(v);
if (source instanceof Spanned) {
SpannableString sp = new SpannableString(s);
TextUtils.copySpansFrom((Spanned) source, start, end, null, sp, 0);
return sp;
} else {
return s;
}
} else {
return null; // keep original
}
}
private String replaceEmoji(CharSequence source) {
String notAllowedCharactersRegex = "[^a-zA-Z0-9##\\$%\\&\\-\\+\\(\\)\\*;:!\\?\\~`£\\{\\}\\[\\]=\\.,_/\\\\\\s'\\\"<>\\^\\|÷×]";
return source.toString()
.replaceAll(notAllowedCharactersRegex, "");
}
};
}
Can anyone help me with this ?

Restrict the EditText to use given digits only.
<EditText
........
android:inputType="textPersonName"
android:digits="aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyY zZ0123456789"
/>

As per my understanding all emoji contains /u so I used it like this
public static InputFilter[] getEmojiFilter(String blockChars) {
return new InputFilter[]{(source, start, end, dest, dstart, dend) -> {
String source1= StringEscapeUtils.escapeJava(source.toString());
for (int i = start; i < end; i++) {
if (source != null && blockChars.contains("" + source1.charAt(i))) {
return source.subSequence(start, i);
}
}
return null;
}};
}
and Write below line for Edittext
editext.setFilters(getEmojiFilter("'\"\\//\\u"));

If you want alphabets only in edittext, Add this line in edittext tag
android:digits="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

Try this one....worked for me
private EditText InputText;
private String blockCharacterSet = "~#^|$%&*!"; //Special characters to block
private InputFilter filter = new InputFilter() {
#Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
if (source != null && blockCharacterSet.contains(("" + source))) {
return "";
}
return null;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
InputText = (EditText) findViewById(R.id.InputText);
InputText.setFilters(new InputFilter[] { filter });
}

Add This in Strings.xml. It's allow u to enter alphanumeric and space also.
<string name="charset">0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXY Z</string>

This answer worked for me. I searched different questions and I got my answer.

setFilters(new InputFilter[]{new EmojiExcludeFilter()});
private class EmojiExcludeFilter implements InputFilter {
#Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
String specialChars = "/*!##$%^&*()\"{}_[]|\\?/<>,.:-'';§£¥...";
for (int i = start; i < end; i++) {
int type = Character.getType(source.charAt(i));
if (type == Character.SURROGATE || type == Character.OTHER_SYMBOL || type == Character.MATH_SYMBOL || specialChars.contains("" + source)|| Character.isWhitespace(0)) {
return "";
}
}
return null;
}
}

Set InputFilter for white space and maximum length

I want to use Input filter where I can prevent first space entering AND max length of my edit text limited to 200 characters.
so far I have this:
Hot to I put the maxlength into the same filter
private void setInputFilterForEmailAndPwd(final EditText amountEditText) {
InputFilter filter = new InputFilter() {
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
for (int i = start; i < end; i++) {
if (Character.isSpace(source.charAt(i))) {
return "";
}
}
return null;
}
};
amountEditText.setFilters(new InputFilter[] { filter });
}
setInputFilterForEmailAndPwd(emailEdit);

I found the solution
I put new Input Filter, instead of setInputFilterForEmailAndPwd:
InputFilter filter = new InputFilter() {
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
for (int i = start; i < end; i++) {
if (Character.isWhitespace(source.charAt(i))) {
return "";
}
}
return null;
}
};
and then:
emailEdit.setFilters(new InputFilter[] { filter, new InputFilter.LengthFilter(200) });

Disable specific keys on the keyboard

As you can disable certain keys on the keyboard to prevent the user to input wrong characters?

the following code is to disable numbers and chars
{
final 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 (Character.isDigit(source.charAt(i))||Character.isLetter(source.charAt(i)))
{
return "";
}
}
return null;
}
};
answerTXT.setFilters(new InputFilter[]{filter});
}

How to exclude special characters from android keypad for EditText

Hi I want to show only numbers and characters on the keypad for EditText in android, I did try to add the attribute android:inputType = text|number but it did not work.
Please help me with any other better suggestion. thanks in advance.

Use the filter for that. Here I am adding the code for filter.
EditText etName = (EditText)findViewById(R.id.etName);
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 (!Character.isLetterOrDigit(source.charAt(i))) {
return "";
}
}
return null;
}
};
etName.setFilters(new InputFilter[]{filter});

try to add the digits parameter to your editText:
android:digits="abcde.....012345789"

The solution with InputFilter provided here is not 100% correct as it will replace and throw out some valid characters from the input if they are right next to the invalid one.
For example we need to filter out all special characters and you enter text: olala[
The EditText field will pass the whole olala[ sentence to the filter and the return value will be "" meaning that we throw out valid olala as well.
Here is my solution:
InputFilter filter = (source, start, end, dest, dstart, dend)->{
for (int i = start; i < end; i++) {
char symbol = source.charAt(i);
if (!isValidCharacter(symbol)) {
StringBuilder buf = new StringBuilder();
for(int j = start; j < end; j++)
{
symbol = source.charAt(j);
if(isValidCharacter(symbol)) buf.append(symbol);
}
return buf.toString();
}
}
return null;
};
We need double loop here to avoid memory allocation of StringBuilder for every method call with valid characters.

If you want to add spaces you can give space after the last digit.
android:digits="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 "

try using this method it worked for me:
public static InputFilter[] getFilter(String blockChars) {
return new InputFilter[]{(source, start, end, dest, dstart, dend) -> {
for (int i = start; i < end; i++) {
if (source != null && blockChars.contains("" + source.charAt(i))) {
return source.subSequence(start, i);
}
}
return null;
}};
add this line for your edit text
edittext.setFilters(getFilter("#~"));

The expected solution is to restrict user from entering special characters from keyboard.
The below solution uses RegX but adds it to strings.xml file so that will be taken care at the time of creating multilingual xmls.
Strings.xml
<string name="alpha_numeric_regx">[a-zA-Z 0-9]+</string>
Source file
//Extracting forehand to avoid multiple calls to getString from Filter
String alphaNumericRegX = getString(R.string.alpha_numeric_regx);
mEditTextOtp.setFilters(new InputFilter[]{(source, start, end, dest, dStart, dEnd) -> {
for (int i = 0; i < source.length(); i++) {
if (source.equals("")) {
return source;
}
if (source.toString().matches(alphaNumericRegX)) {
return source;
}
return "";
}
return null;
}});
Hope this will solve the prob. for new guys. :)

Kotlin
et_search.keyListener = DigitsKeyListener.getInstance(getString(R.string.alphanumeric))
String.xml
<string name="alphanumeric">0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ</string>

//大兄弟，这么做就可以了。
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 (isChineseChar(source.charAt(i))) {
return "";
}
}
return null;
}
};
etName.setFilters(new InputFilter[]{filter});
//一条简单的规则。
private static boolean isChineseChar(char c) {
Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
return ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS;
}

Its Working
Restrict Special Symbol in Edittext
private EditText your_editText ;
private String blockCharacters = "(~*#^|$%&!";
private InputFilter filter = new InputFilter() {
#Override
public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
if (source != null && blockCharacters.contains(("" + source))) {
return "";
}
return null;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
your_editText = (EditText) findViewById(R.id.your_editText);
your_editText .setFilters(new InputFilter[] { filter });
}
}

I couldn't edit a previous answer, so I did a Kotlin version of it (including whitespace):
private val userNameFilter =
InputFilter { source, start, end, dest, dStart, dEnd ->
for (i in start until end) {
if (!Character.isLetterOrDigit(source[i]) && !Character.isWhitespace(source[i])) {
return#InputFilter ""
}
}
null
}