android on Text Change Listener

Question

I have a situation  where there are two fields  field1 and field2  All I want to do is empty field2 when field1 is changed and vice versa  So at the end only one field has content on it   field1    EditText findViewById R id field1   field2    EditText findViewById R id field2    field1 addTextChangedListener new TextWatcher         public void afterTextChanged Editable s         public void beforeTextChanged CharSequence s  int start       int count  int after             public void onTextChanged CharSequence s  int start       int before  int count          field2 setText                  field2 addTextChangedListener new TextWatcher         public void afterTextChanged Editable s         public void beforeTextChanged CharSequence s  int start       int count  int after             public void onTextChanged CharSequence s  int start       int before  int count         field1 setText                   It works fine if I attach addTextChangedListener to field1 only  but when I do it for both fields the app crashes  Obviously because they try to change each other indefinitely  Once field1 changes it clears field2 at this moment field2 is changed so it will clear field1 and so on     Can someone suggest any solution

User · Answer

We can remove the TextWatcher for a field just before editing its text then add it back after editing the text.

Declare Text Watchers for both field1 and field2 as separate variables to give them a name: e.g. for field1

private TextWatcher Field_1_Watcher = new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }

    @Override
    public void afterTextChanged(Editable s) {
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

};

then add the watcher using its name: field1.addTextChangedListener(Field_1_Watcher) for field1, and field2.addTextChangedListener(Field_2_Watcher) for field2

Before changing the field2 text remove the TextWatcher: field2.removeTextChangedListener(Field_2_Watcher) change the text: field2.setText("")

then add the TextWatcher back: field2.addTextChangedListener(Field_2_Watcher)

Do the same for the other field

User · Answer

If you are using Kotlin for Android development then you can add TextChangedListener   using this code   myTextField addTextChangedListener object   TextWatcher          override fun afterTextChanged s  Editable               override fun beforeTextChanged s  CharSequence   start  Int  count  Int  after  Int              override fun onTextChanged s  CharSequence   start  Int  before  Int  count  Int

User · Answer

check String before set another EditText to empty  if Field1 is empty then why need to change again to         so you can check the size of Your String with s lenght   or any other solution   another way that you can check lenght of String is   String sUsername   Field1 getText   toString    if   sUsername matches           do your job

User · Answer

You can also use the hasFocus   method   public void onTextChanged CharSequence s  int start       int before  int count         if  Field2 hasfocus              Field1 setText                    Tested this for a college assignment I was working on to convert temperature scales as the user typed them in  Worked perfectly  and it s way simpler

User · Answer

editText addTextChangedListener new TextWatcher                  Override             public void beforeTextChanged CharSequence charSequence  int i  int i1  int i2                                Override             public void onTextChanged CharSequence charSequence  int i  int i1  int i2                    if  noteid    -1                        MainActivity notes set noteid  String valueOf charSequence                        MainActivity arrayAdapter notifyDataSetChanged                                                 Override             public void afterTextChanged Editable editable                                 in this code noteid is basically arguments taken back which is being putted into the indent or passed through the indent     Intent intent   getIntent             noteid   intent getIntExtra  noteid   -1     the code on the downside is basically the extra code  if you want to understand more clearly   how to make the menu or insert the menu in our code        create the  menu folder this the folder created by going into the raw     - gt rightclick- gt      directory- gt name the folder as you wish- gt      then click on the directory formed- gt      then click on new file and then name for file as you wish ie the folder name file     and now type the 2 lines code in it and see the magic    new activity code named as NoteEditor java for editing purpose my app is basicley the note app   package com example elavi notes  import android content Intent  import android support v7 app AppCompatActivity  import android os Bundle  import android text Editable  import android text TextWatcher  import android widget EditText  import android widget Toast   import static android media CamcorderProfile get  public class NoteEditorActivity extends AppCompatActivity       EditText editText      int noteid       Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity note editor           editText   findViewById R id editText           Intent intent   getIntent             noteid   intent getIntExtra  noteid   -1           if  noteid    -1                String text   MainActivity notes get noteid               editText setText text               Toast makeText getApplicationContext    The arraylist content is  MainActivity notes get noteid  Toast LENGTH SHORT  show                      else                       Toast makeText getApplicationContext    Here we go  Toast LENGTH SHORT  show                MainActivity notes add                  noteid MainActivity notes size  -1                    editText addTextChangedListener new TextWatcher                  Override             public void beforeTextChanged CharSequence charSequence  int i  int i1  int i2                                Override             public void onTextChanged CharSequence charSequence  int i  int i1  int i2                    if  noteid    -1                        MainActivity notes set noteid  String valueOf charSequence                        MainActivity arrayAdapter notifyDataSetChanged                                                 Override             public void afterTextChanged Editable editable

User · Answer

I know this is old but someone might come across this again someday   I had a similar problem where I would call setText on a EditText and onTextChanged would be called when I didn t want it to  My first solution was to write some code after calling setText   to undo the damage done by the listener  But that wasn t very elegant  After doing some research and testing I discovered that using getText   clear   clears the text in much the same way as setText      but since it isn t setting the text the listener isn t called  so that solved my problem  I switched all my setText     calls to getText   clear    and I didn t need the bandages anymore  so maybe that will solve your problem too   Try this   Field1    EditText findViewById R id field1   Field2    EditText findViewById R id field2    Field1 addTextChangedListener new TextWatcher         public void afterTextChanged Editable s         public void beforeTextChanged CharSequence s  int start       int count  int after             public void onTextChanged CharSequence s  int start       int before  int count          Field2 getText   clear                Field2 addTextChangedListener new TextWatcher         public void afterTextChanged Editable s         public void beforeTextChanged CharSequence s  int start       int count  int after             public void onTextChanged CharSequence s  int start       int before  int count         Field1 getText   clear

User · Answer

Add background dynamically in onCreate method   getWindow   setBackgroundDrawableResource R drawable background     also remove background from XML

User · Answer

Another solution that may help someone  There are 2 EditText which change instead of each other after editing  By default  it led to cyclicity  use variable  Boolean uahEdited   false  Boolean usdEdited   false   add TextWatcher uahEdit   findViewById R id uahEdit   usdEdit   findViewById R id usdEdit    uahEdit addTextChangedListener new TextWatcher              Override         public void beforeTextChanged CharSequence s  int start  int count  int after                if   usdEdited                    uahEdited   true                                    Override         public void onTextChanged CharSequence s  int start  int before  int count                String tmp   uahEdit getText   toString                 if  tmp isEmpty    amp  amp  uahEdited                    uah   Double valueOf tmp                   usd   uah   27                  usdEdit setText String valueOf usd                  else if  tmp isEmpty                      usdEdit getText   clear                                      Override         public void afterTextChanged Editable s                uahEdited   false                     usdEdit addTextChangedListener new TextWatcher              Override         public void beforeTextChanged CharSequence s  int start  int count  int after                if   uahEdited                    usdEdited   true                                    Override         public void onTextChanged CharSequence s  int start  int before  int count                String tmp   usdEdit getText   toString                 if   tmp isEmpty    amp  amp  usdEdited                    usd   Double valueOf tmp                   uah   usd   27                  uahEdit setText String valueOf uah                  else if  tmp isEmpty                      uahEdit getText   clear                                      Override         public void afterTextChanged Editable s                usdEdited   false                     Don t criticize too much  I am a novice developer

User · Answer

I have also faced the same problem and keep on getting stackOverflow exceptions  and I come with the following solution   edt amnt sent addTextChangedListener new TextWatcher              Override     public void afterTextChanged Editable s            if  skipOnChange              return           skipOnChange   true          try                 method           catch  NumberFormatException e                   TODO Auto-generated catch block             e printStackTrace              finally               skipOnChange   false                       edt amnt receive addTextChangedListener new TextWatcher           Override     public void afterTextChanged Editable s             if  skipOnChange              return           skipOnChange   true          try                 method           catch  NumberFormatException e                   TODO Auto-generated catch block             e printStackTrace              finally               skipOnChange   false                        declared initially boolean skipOnChange   false

User · Answer

You can add a check to only clear when the text in the field is not empty  i e when the length is different than 0    field1 addTextChangedListener new TextWatcher          Override    public void afterTextChanged Editable s          Override        public void beforeTextChanged CharSequence s  int start       int count  int after              Override        public void onTextChanged CharSequence s  int start       int before  int count          if s length      0          field2 setText                  field2 addTextChangedListener new TextWatcher          Override    public void afterTextChanged Editable s          Override    public void beforeTextChanged CharSequence s  int start       int count  int after              Override    public void onTextChanged CharSequence s  int start       int before  int count          if s length      0           field1 setText                   Documentation for TextWatcher here   Also please respect naming conventions

User · Answer

I wrote my own extension for this  very helpful for me   Kotlin   You can write only like that     editText customAfterTextChanged   editable - gt         You have accessed the editable object       My extension     fun EditText customAfterTextChanged action   Editable  - gt  Unit       this addTextChangedListener object   TextWatcher          override fun beforeTextChanged p0  CharSequence   p1  Int  p2  Int  p3  Int            override fun onTextChanged p0  CharSequence   p1  Int  p2  Int  p3  Int            override fun afterTextChanged editable  Editable             action editable

User · Answer

A bit late of a answer  but here is a reusable solution          An extension of TextWatcher which stops further callbacks being called as     a result of a change happening within the callbacks themselves      public abstract class EditableTextWatcher implements TextWatcher        private boolean editing        Override     public final void beforeTextChanged CharSequence s  int start                                                       int count  int after            if  editing              return           editing   true          try               beforeTextChange s  start  count  after             finally               editing   false                       protected abstract void beforeTextChange CharSequence s  int start                                                        int count  int after         Override     public final void onTextChanged CharSequence s  int start                                                   int before  int count            if  editing              return           editing   true          try               onTextChange s  start  before  count             finally               editing   false                       protected abstract void onTextChange CharSequence s  int start                                               int before  int count         Override     public final void afterTextChanged Editable s            if  editing              return           editing   true          try               afterTextChange s             finally               editing   false                       public boolean isEditing             return editing             protected abstract void afterTextChange Editable s       So when the above is used  any setText   calls happening within the TextWatcher will not result in the TextWatcher being called again          A setText   call in any of the callbacks below will not result in TextWatcher being     called again      public class MyTextWatcher extends EditableTextWatcher         Override     protected void beforeTextChange CharSequence s  int start  int count  int after                Override     protected void onTextChange CharSequence s  int start  int before  int count                Override     protected void afterTextChange Editable s

User · Answer

var filenameText   findViewById R id filename  as EditText filenameText addTextChangedListener object   TextWatcher       override fun afterTextChanged s  Editable             filename   filenameText text toString           Log i  quot FileName   quot   filename                 override fun beforeTextChanged p0  CharSequence   p1  Int  p2  Int  p3  Int         override fun onTextChanged s  CharSequence   start  Int  before  Int  count  Int

User · Answer

In Kotlin simply use KTX extension function   It uses TextWatcher   yourEditText doOnTextChanged   text  start  count  after - gt              action which will be invoked when the text is changing          import core-KTX   implementation  androidx core core-ktx 1 2 0

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