Android EditText delete backspace key event

Question

How can I detect delete  backspace  key event for a editText  I ve tried using TextWatcher  but when the editText is empty  when I press delete key  nothing happens  I want to detect delete key press foe an editText even if it has no text

User · Answer

This is just an addition to Idris s answer  adding in the override to deleteSurroundingText as well  I found more info on that here  Android  Backspace in WebView BaseInputConnection  package com elavon virtualmerchantmobile utils   import java util Random   import android content Context  import android graphics Color  import android util AttributeSet  import android view KeyEvent  import android view inputmethod EditorInfo  import android view inputmethod InputConnection  import android view inputmethod InputConnectionWrapper  import android widget EditText   public class ZanyEditText extends EditText        private Random r   new Random         public ZanyEditText Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle              public ZanyEditText Context context  AttributeSet attrs            super context  attrs              public ZanyEditText Context context            super context              public void setRandomBackgroundColor             setBackgroundColor Color rgb r nextInt 256   r nextInt 256   r                  nextInt 256                 Override     public InputConnection onCreateInputConnection EditorInfo outAttrs            return new ZanyInputConnection super onCreateInputConnection outAttrs                   true              private class ZanyInputConnection extends InputConnectionWrapper            public ZanyInputConnection InputConnection target  boolean mutable                super target  mutable                       Override         public boolean sendKeyEvent KeyEvent event                if  event getAction      KeyEvent ACTION DOWN                      amp  amp  event getKeyCode      KeyEvent KEYCODE DEL                    ZanyEditText this setRandomBackgroundColor                       Un-comment if you wish to cancel the backspace                     return false                            return super sendKeyEvent event                        Override         public boolean deleteSurroundingText int beforeLength  int afterLength                          magic  in latest Android  deleteSurroundingText 1  0  will be called for backspace             if  beforeLength    1  amp  amp  afterLength    0                       backspace                 return sendKeyEvent new KeyEvent KeyEvent ACTION DOWN  KeyEvent KEYCODE DEL                        amp  amp  sendKeyEvent new KeyEvent KeyEvent ACTION UP  KeyEvent KEYCODE DEL                               return super deleteSurroundingText beforeLength  afterLength

User · Answer

I am also faced same issue in Dialog   because I am using setOnKeyListener   But I set default return true  After change like below code it working fine for me         mDialog setOnKeyListener new Dialog OnKeyListener               Override         public boolean onKey DialogInterface arg0  int keyCode                               KeyEvent event                if  keyCode    KeyEvent KEYCODE BACK                    mDialog dismiss                    return true                            return false   this line is important

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I sent 2 days to find a solution and I figured out a working one     on soft keys   public TextWatcher textWatcher   new TextWatcher      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  count    0              Put your code here            Runs when delete backspace pressed on soft key  tested on htc m8            You can use EditText getText   length   to make if statements here                   Override     public void afterTextChanged Editable s              After add the textwatcher to your EditText   yourEditText addTextChangedListener textWatcher     I hope it works on another android devices too  samsung  LG  etc

User · Answer

Example of creating EditText with TextWatcher  EditText someEdit new EditText this     create TextWatcher for our EditText TextWatcher1 TW1   new TextWatcher1 someEdit     apply our TextWatcher to EditText         someEdit addTextChangedListener TW1     custom TextWatcher  public class TextWatcher1 implements TextWatcher           public EditText editText    constructor         public TextWatcher1 EditText et               super                editText   et    Code for monitoring keystrokes             editText setOnKeyListener new View OnKeyListener                      Override                 public boolean onKey View v  int keyCode  KeyEvent event                        if keyCode    KeyEvent KEYCODE DEL                           editText setText                                                    return false                                                Some manipulation with text         public void afterTextChanged Editable s                if editText getText   length      12                   editText setText editText getText   delete editText getText   length   - 1  editText getText   length                      editText setSelection editText getText   toString   length                               if  editText getText   length    2  editText getText   length    5  editText getText   length    8                   editText setText editText getText                         editText setSelection editText getText   toString   length                                     public void beforeTextChanged CharSequence s  int start  int count  int after                     public void onTextChanged CharSequence s  int start  int before  int count

User · Answer

I have found a really simple solution which works with a soft keyboard   override fun onTextChanged text  CharSequence   start  Int  before  Int  count  Int        text  let            if count  lt  before                Toast makeText context   backspace pressed   Toast LENGTH SHORT  show                  implement your own code

User · Answer

My simple solution which works perfectly  You should to add a flag  My code snippet   editText addTextChangedListener new TextWatcher              Override         public void beforeTextChanged CharSequence s  int start  int count  int after                if  after  lt  count                    isBackspaceClicked   true                else                   isBackspaceClicked   false                                    Override         public void onTextChanged CharSequence s  int start  int before  int count                Override         public void afterTextChanged Editable s                if   isBackspaceClicked                       Your current code               else                      Your  backspace  handling

User · Answer

There is a similar question in the Stackoverflow  You need to override EditText in order to get access to InputConnection object which contains deleteSurroundingText method  It will help you to detect deletion  backspace  event   Please  take a look at a solution I provided there Android - cannot capture backspace delete press in soft  keyboard

User · Answer

Based on  Jiff ZanyEditText here is WiseEditText with setSoftKeyListener OnKeyListener   package com locopixel seagame ui custom   import java util Random   import android content Context  import android graphics Color  import android support v7 widget AppCompatEditText  import android util AttributeSet  import android view KeyEvent  import android view inputmethod EditorInfo  import android view inputmethod InputConnection  import android view inputmethod InputConnectionWrapper   public class WiseEditText extends AppCompatEditText        private Random r   new Random        private OnKeyListener keyListener       public WiseEditText Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle              public WiseEditText Context context  AttributeSet attrs            super context  attrs              public WiseEditText Context context            super context               Override     public InputConnection onCreateInputConnection EditorInfo outAttrs            return new MyInputConnection super onCreateInputConnection outAttrs                   true              private class MyInputConnection extends InputConnectionWrapper            public MyInputConnection InputConnection target  boolean mutable                super target  mutable                       Override         public boolean sendKeyEvent KeyEvent event                if  keyListener    null                    keyListener onKey WiseEditText this event getKeyCode   event                             return super sendKeyEvent event                       Override         public boolean deleteSurroundingText int beforeLength  int afterLength                          magic  in latest Android  deleteSurroundingText 1  0  will be called for backspace             if  beforeLength    1  amp  amp  afterLength    0                       backspace                 return sendKeyEvent new KeyEvent KeyEvent ACTION DOWN  KeyEvent KEYCODE DEL                        amp  amp  sendKeyEvent new KeyEvent KeyEvent ACTION UP  KeyEvent KEYCODE DEL                               return super deleteSurroundingText beforeLength  afterLength                         public void setSoftKeyListener OnKeyListener listener           keyListener   listener

User · Answer

NOTE  onKeyListener doesn t work for soft keyboards   You can set OnKeyListener for you editText so you can detect any key press EDIT  A common mistake we are checking KeyEvent KEYCODE BACK for backspace  but really it is KeyEvent KEYCODE DEL  Really that name is very confusing     editText setOnKeyListener new OnKeyListener                           Override     public boolean onKey View v  int keyCode  KeyEvent event              You can identify which key pressed buy checking keyCode value with KeyEvent KEYCODE          if keyCode    KeyEvent KEYCODE DEL                    this is for backspace                   return false

User · Answer

for some one who s using Kotlin  addOnTextChanged is not flexible enought to handle some cases  ex  detect if user press delete when edit text was empty   setOnkeyListener worked even soft keyboard or hardkeyboard  but just on some devices  In my case  it work on Samsung s8 but not work on Xiaomi mi8 se    if you using kotlin  you can use crossline function doOnTextChanged  it s the same as addOnTextChanged but callback is triggered even edit text was empty   NOTE  doOnTextChanged is a part of Android KTX library

User · Answer

This question may be old but the answer is really simple using a TextWatcher   int lastSize 0   Override public void onTextChanged CharSequence charSequence  int i  int i1  int i2          2  compare the old length of the text with the new one       3  if the length is shorter  then backspace was clicked     if  lastSize  gt  charSequence length                4  Backspace was clicked           5  perform action             1  get the current length of of the text     lastSize   charSequence length

User · Answer

I have tested  Jeff s solution on version 4 2  4 4  6 0  On 4 2 and 6 0  it works well  But on 4 4  it doesn t work    I found an easy way to work around this problem  The key point is to insert an invisible character into the content of EditText at the begining  and don t let user move cursor before this character  My way is to insert a white-space character with an ImageSpan of Zero Width on it  Here is my code                    Override                 public void afterTextChanged Editable s                        String ss   s toString                        if   ss startsWith                                 int selection   holder editText getSelectionEnd                            s insert 0                                ss   s toString                            holder editText setSelection selection   1                                             if  ss startsWith                                 ImageSpan   spans   s getSpans 0  1  ImageSpan class                           if  spans    null    spans length    0                                s setSpan new ImageSpan getResources   getDrawable R drawable zero wdith drawable    0   1  Spanned SPAN EXCLUSIVE EXCLUSIVE                                                                       And we need custom an EditText which has a SelectionChangeListener  public class EditTextSelectable extends android support v7 widget AppCompatEditText   public interface OnSelectChangeListener       void onSelectChange int start  int end      private OnSelectChangeListener mListener   public void setListener OnSelectChangeListener listener        mListener   listener        constructors      Override protected void onSelectionChanged int selStart  int selEnd        if  mListener    null            mListener onSelectChange selStart  selEnd             super onSelectionChanged selStart  selEnd          And the last step  holder editText setListener new EditTextSelectable OnSelectChangeListener                      Override                 public void onSelectChange int start  int end                        if  start    0  amp  amp  holder editText getText   length      0                            holder editText setSelection 1  Math max 1  end                                                              And now  we are done  We can detect backspace key event when EditText has no actual content  and user will know nothing about our trick

User · Answer

My problem was  that I had custom Textwatcher  so I didn t want to add OnKeyListener to an EditText as well as I didn t want to create custom EditText  I wanted to detect if backspace was pressed in my afterTextChanged method  so I shouldn t trigger my event   This is how I solved this  Hope it would be helpful for someone   public class CustomTextWatcher extends AfterTextChangedTextWatcher    private boolean backspacePressed    Override public void afterTextChanged Editable s        if   backspacePressed            triggerYourEvent              Override public void onTextChanged CharSequence s  int start  int before  int count        super onTextChanged s  start  before  count       backspacePressed   count    0    if count    0  backspace is pressed

User · Answer

Belated but it may help new visitors  use TextWatcher   instead will help alot and also it will work for both soft and hard keyboard as well   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  charSequence length    gt  0                          Here it means back button is pressed and edit text is now empty                   else                        Here edit text has some text                                               Override             public void afterTextChanged Editable editable

User · Answer

You could set a key listener on the activity  and in the callback method  you could detect  which key the user hit  The code below is for your reference  Hope it helps     after user hits keys  this method would be called  public boolean onKeyUp int keyCode  KeyEvent event            if  editText isFocused                  switch  keyCode                case KeyEvent KEYCODE DEL     delete key                 Log i  INFO    delete key hit      you should see this log in ddms after you hit delete key                 break                                  return super onKeyUp keyCode  event

User · Answer

Here is my easy solution  which works for all the API s   private int previousLength  private boolean backSpace            Override public void beforeTextChanged CharSequence s  int start  int count  int after        previousLength   s length        Override public void onTextChanged CharSequence s  int start  int before  int count        Override public void afterTextChanged Editable s        backSpace   previousLength  gt  s length         if  backSpace                do your stuff                 UPDATE 17 04 18   As pointed out in comments  this solution doesn t track the backspace press if EditText is empty  the same as most of the other solutions   However  it s enough for most of the use cases  P S  If I had to create something similar today  I would do     public abstract class TextWatcherExtended implements TextWatcher        private int lastLength       public abstract void afterTextChanged Editable s  boolean backSpace         Override     public void beforeTextChanged CharSequence s  int start  int count  int after            lastLength   s length                Override     public void afterTextChanged Editable s            afterTextChanged s  lastLength  gt  s length                 Then just use it as a regular TextWatcher    editText addTextChangedListener new TextWatcherExtended              Override         public void afterTextChanged Editable s  boolean backSpace                  Here you are  You got missing  backSpace  flag                     Override         public void onTextChanged CharSequence s  int start  int before  int count                   Do something useful if you wish                 Or override it in TextWatcherExtended class if want to avoid it here

User · Answer

It s been a while since you asked but I just had the same issue  As already mentioned by Estel the problem with key listeners is that they only work with hardware keyboards  To do this with an IME  soft keyboard   the solution is a bit more elaborate    The single method we actually want to override is sendKeyEvent in the EditText s InputConnection class  This method is called when key events occur in an IME  But in order to override this  we need to implement a custom EditText which overrides the onCreateInputConnection method  wrapping the default InputConnection object in a proxy class      Sounds complicated  but here s the simplest example I could contrive   public class ZanyEditText extends EditText        private Random r   new Random         public ZanyEditText Context context  AttributeSet attrs  int defStyle            super context  attrs  defStyle              public ZanyEditText Context context  AttributeSet attrs            super context  attrs              public ZanyEditText Context context            super context              public void setRandomBackgroundColor             setBackgroundColor Color rgb r nextInt 256   r nextInt 256   r                  nextInt 256                 Override     public InputConnection onCreateInputConnection EditorInfo outAttrs            return new ZanyInputConnection super onCreateInputConnection outAttrs                   true              private class ZanyInputConnection extends InputConnectionWrapper            public ZanyInputConnection InputConnection target  boolean mutable                super target  mutable                       Override         public boolean sendKeyEvent KeyEvent event                if  event getAction      KeyEvent ACTION DOWN                      amp  amp  event getKeyCode      KeyEvent KEYCODE DEL                    ZanyEditText this setRandomBackgroundColor                       Un-comment if you wish to cancel the backspace                     return false                            return super sendKeyEvent event                         The line with the call to setRandomBackgroundColor is where my special backspace action occurs  In this case  changing the EditText s background colour   If you re inflating this from XML remember to use the full package name as the tag    lt cc buttfu test ZanyEditText android layout width  fill parent  android layout height  wrap content  android id    id somefield   gt  lt  cc buttfu test ZanyEditText gt

User · Answer

This seems to be working for me    public void onTextChanged CharSequence s  int start  int before  int count        if  before - count    1            onBackSpace          else if  s subSequence start  start   count  toString   equals   n              onNewLine

[android] Android EditText delete(backspace) key event

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