InputFilter

InputFilters can be attached to Editables to constrain the changes that can be made to them.

ex.

        EditText edit = (EditText)findViewById(R.id.edit);
        InputFilter[] FilterArray = new InputFilter[2];
        FilterArray[0] = new InputFilter.LengthFilter(4); //Limit length of the text 
        FilterArray[1] = new InputFilter.AllCaps();   //capitalize all the lower case letters
        edit.setFilters(FilterArray);