How to restrict some character in editText

Question

Please don't hurry to mark this message as "duplicated". I can't find an appropriate example. Suppose I'd like to restrict the char "{" in editText.

Let's consider a few variants of my code. I tried them on emulator only.

       editName.addTextChangedListener(new TextWatcher() {
        public void afterTextChanged(Editable s) {
            String txt=s.toString();
            int len=txt.length();
            toastDebug("len="+myIntToStr(len));
            if (len>0) {
                try {
                    int pos=txt.indexOf("{");
                    if (pos>=0) s.replace(pos,pos+1,"");
                }
                catch(Exception e) {}
            }
        }

If I type "{" quiickly it leads to "stackOverFlow" crash. Suppose I type "abcd{{{{{{{" slowly. For the first view it looks okay, no "{" in editText. But if I type backspace, it does not remove "abcd", it removes those invisible "{{{{{"

I tried to change the editText inside of "afterTextChanged". The code below causes stackOverflowError again.

            public void afterTextChanged(Editable s) {
            String txt=s.toString();
            int len=txt.length();
            if (len>0) {
                try {
                   editName.setText(txt)
                   or
                   s.clear
                   s.append(txt)
                }
                catch(Exception e) {}
            }
        }

Many examples with code like this clear my editText after I type "{".

Well, I modified this code as follows:

    editName.setFilters(new InputFilter[] { filterName });

    private InputFilter filterName = new InputFilter() {
    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        if (source==null) return null;
            return source.toString().replace("{","");
    }
};

Now it works. But my android:maxLength="25" does not work. It is possible to type any numbers of characters.

So I am puzzled how can I restrict simple character in editText. Any ideas? Thanks!

Answer 1

You can restrict the characters that the user can enter in the EditText by setting a TextWatcher on the widget and inserting the logic below:

// we are interested in this callback
@Override
public void afterTextChanged(Editable s) {
    String result = s.toString().replaceAll("\\{", "");
    if (!s.toString().equals(result)) {
         edit.setText(result); // "edit" being the EditText on which the TextWatcher was set
         edit.setSelection(result.length()); // to set the cursor at the end of the current text             
    }
}

The \\ is required(and for other characters) because the { character has a special meaning in a pattern.

Answer 2

You can use it by xml as well

android:digits="0,1,2,3,4,5,6,7,8,9,.,@,qwertzuiopasdfghjklyxcvbnm"

or

android:digits="abcdefghijklmnopqrstuvwxyz1234567890 "

Which u want put here.

Answer 3

My assumption is android:maxLength actually is a InputFilter that added to your EditText. so if you want to add more InputFilter, you must get the current InputFilter array of your EditText and append it with your own InputFIlter. I do this and this works.

EditText editName = (EditText) findViewById(R.id.editText1);

        InputFilter filterName = new InputFilter() {
        @Override
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
            if (source==null) return null;
            return source.toString().replace("{","");
        }
    };

    //Get current Input Filter from EditText
    InputFilter[] oldInputFilter = editName.getFilters();
    //Create arrays for new InputFilter
    InputFilter[] newInputFilter = new InputFilter[oldInputFilter.length+1];
    //Copy all old Input Filter to new one
    System.arraycopy(oldInputFilter, 0, newInputFilter, 0, oldInputFilter.length);
    //Add your own input filter
    newInputFilter[newInputFilter.length-1] = filterName;
    //Set the new Input Filter
    editName.setFilters(newInputFilter);

Answer 4

The above correct answer only work for one EditText.
But this work for all the EditText in you XML.

        InputFilter filter = new InputFilter() { 
            boolean canEnterSpace = false;

            public CharSequence filter(CharSequence source, int start, int end,
                    Spanned dest, int dstart, int dend) {

                if(_edtUsername.getText().toString().equals(""))
                {
                    canEnterSpace = false;
                }

                StringBuilder builder = new StringBuilder();

                for (int i = start; i < end; i++) { 
                    char currentChar = source.charAt(i);

                    if (Character.isLetterOrDigit(currentChar) || currentChar == '{') {
                        builder.append(currentChar);
                        canEnterSpace = false;
                    }

                    if(Character.isWhitespace(currentChar) && canEnterSpace) {
                        builder.append(currentChar);
                    }


                }
                return builder.toString();          
            }

        };
        _edtUsername.setFilters(new InputFilter[]{filter});
        _edtFirstName.setFilters(new InputFilter[]{filter});
        _edtLastName.setFilters(new InputFilter[]{filter});

Thanks

Answer 5

Here I replaced with ".com" to ""

Xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.edittextdemo.MainActivity" >

    <EditText
        android:id="@+id/edt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</RelativeLayout>

// Java

public class MainActivity extends Activity {

    private EditText edt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edt = (EditText) findViewById(R.id.edt);
        edt.addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                    int arg3) {
                // TODO Auto-generated method stub

            }

            @Override
            public void afterTextChanged(Editable s) {
                String currentStr = s.toString().replaceAll(".com", "");
                if (!s.toString().equals(currentStr)) {
                    edt.setText(currentStr); 
                    edt.setSelection(currentStr.length());              
                }
            }
        });
    }