Develop Reference

Is it okay to call MutableLiveData's setValue's method rapildy?

I have an EditText where I need to hold its value in a MutableLiveData in a viewmodel.
Is it okay to be calling the method setValue("the changed edittext string") every time the user edits something in the EditText?
The reason why I'm doing this is to keep the data alive even if the user for example rotated the screen.
Is there any other way to achieve the same result? Cause I feel like it can be expensive and it's a bad practice calling the method over and over. here's an example in an activity:
public class NoteActivity extends AppCompatActivity {
private ActivityNoteBinding binding;
private NoteViewModel viewmodel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = DataBindingUtil.setContentView(this, R.layout.activity_note);
viewmodel = new ViewModelProvider(this).get(NoteViewModel.class);
addObservers();
addListeners();
}
private void addObservers() {
viewmodel.noteBodyLiveData.observe(this, s -> binding.noteBody.setText(s));
}
private void addListeners() {
binding.noteBody.addTextChangedListener(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) {
viewmodel.noteBodyLiveData.setValue(String.valueOf(s));
}
#Override
public void afterTextChanged(Editable s) {
}
});
}
The LiveData Objects are initialized with the data corresponding to what's in the database.
Thanks in advance!

Search starts when Edittext has at least 3 letters

I am working in an Android studio project. Here I want to implement one searching system. I have an edittext and an imagebutton. When user writers something in edittext and press imagebutton, system shows the relevant data from some database. This much I have covered.
Moreover, I want to implement a system where while user writes at least a specific length of letters (say 3) in edittext, the searching will start automatically. With more adding of letters the searching will be filtered accordingly. Is it possible to do this? Or something similar to this?

on searchview there is this syntax. just check the length of the text
public void onQueryTextChange(String query) {
if(query.length() >= 3) {
searchStarts();
}
}
or if you dont use search view just use 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 (timer != null) {
timer.cancel();
}
}
#Override
public void afterTextChanged(Editable s) {
if(s.length() > 3){
searchStarts();
}
};

you have to add text watcher to your edit text. I will show you the solution with using debounce to avoid updating list all time user type a text.
So lets start with adding textWatcher to your edittext field:
searchField.addTextChangedListener(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) {
//this one is for all letters, you can check the s length eg if(s.length() >= 3)
searchSubject.onNext(s.toString());
}
#Override
public void afterTextChanged(Editable s) {
}
});
This solution use rxjava if you do not want to do it just replace searchSubject with calling your search method.
So the fields:
private PublishSubject<String> searchSubject = PublishSubject.create();
private Subscription searchSubscription;
private String currentSearchPrefix = "";
And subscription (call this method onResume):
/**
* Subscribe to searchSubject to update list of items depends on given prefix.
* Debounce on changes 500 milliseconds
*/
private void subscribeSearch() {
searchSubscription = searchSubject
.debounce(500, TimeUnit.MILLISECONDS)
.onBackpressureLatest()
.subscribe(result -> {
currentSearchPrefix = result;
MainActivity.this.runOnUiThread(this::refreshList);
});
}
My method refreshList just update list by filter it using currentSearchprefix by one of field. Remember to unsubscribe searchSubscription onPause().

EditText aftertextchanged throw StackOverflowError

I have an EditText and a TextWatcher. while testing in our test device we never found StackOverflowError, but once we published our app in Google Play Store, we are getting StackOverflowError issue for some user. Why this is happening, I go through some of link but not got the perfect answer. Is anything need to be done in my code.
Skeleton of my code:
weightEditText.addTextChangedListener(new TextWatcher()
{
#Override
public void onTextChanged(CharSequence s, int start, int before, int count){
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
m_currentWeight = weightEditText.getText().toString();
}
#Override
public void afterTextChanged(Editable s)
{
if(!weightEditText.getText().toString().equals("")) {
Pattern mPattern = Pattern.compile("^([1-9][0-9]{0,2}(\\.[0-9]{0,2}?)?)?$");
Matcher matcher = mPattern.matcher(s.toString());
if (!matcher.find()) {
weightEditText.setText(m_currentWeight);
weightEditText.setSelection(weightEditText.getText().length());
}
}
}
});

To avoid recursion here you need to unregister your textWatcher before setting the text and then reregister it.
Declare the TextWatcher outside the addTextChangedListener(...) method. Then you can do weightEditText.removeTextChangedListener(mWatcher) and weightEditText.addTextChangedListener(mWatcher)

You are trying to call setText() inside of the text watcher which will produce an infinite loop. You can use a flag variable to avoid this.
status variable is set as false by defaut.
status variable indicates whether the TextChange is made by App itself or by the user himself. if it is true, then the TextChange is made by App itself and vice versa.
Try this code. Cheers ! :)
public class MainActivity extends AppCompatActivity {
boolean status=false;//global variable
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
weightEditText.addTextChangedListener(new TextWatcher()
{
#Override
public void onTextChanged(CharSequence s, int start, int before, int count){
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
m_currentWeight = weightEditText.getText().toString();
}
#Override
public void afterTextChanged(Editable s)
{
if(status){
status=false;
return;
}else{
status=true;
if(!weightEditText.getText().toString().equals("")) {
Pattern mPattern = Pattern.compile("^([1-9][0-9]{0,2}(\\.[0-9]{0,2}?)?)?$");
Matcher matcher = mPattern.matcher(s.toString());
if (!matcher.find()) {
weightEditText.setText(m_currentWeight);
weightEditText.setSelection(weightEditText.getText().length());
}
}
}
}
});
}
}

TextWatcher caused crash

Here's a newbie to Android Developing.
While I'm making an app that calculate the calories burnt from exercise, I found that adding a TextWatcher to the EditText will cause crashing even I only add it on the "etEnergy".
I've searched many questions about crashed, but most of them are making a infinity loop in the listener and solved by remove the listener then add it back later. I added that but it doesn't work.
I found this message in Logcat when I can't find the log I made in the method:
Warning ActivityManager(744): Activity pause timeout for ActivityRecord{41ea1128 u0 [package name]/.MainActivity t65 f}
The following are the problem codes in MainActivity.java. Without them I can execute correctly but I need them to complete this app.
protected EditText etEnergy,etWeight,etTime;
protected TextView tvCals;
//double t,a; //don't make any sense in following code.
myTextWatch tw;
class myTextWatch implements 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) {
etEnergy.removeTextChangedListener(this);
etWeight.removeTextChangedListener(this);
etTime.removeTextChangedListener(this);
Log.d("TextWatcher","TextChangedListenerRemoved");
etEnergy.addTextChangedListener(this);
etWeight.addTextChangedListener(this);
etTime.addTextChangedListener(this);
}
#Override
public void afterTextChanged(Editable s) {
}
}//end of class myTextWatch
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
etEnergy=(EditText) findViewById(R.id.etEnergy);
etWeight=(EditText) findViewById(R.id.etWeight);
etTime=(EditText) findViewById(R.id.etTime);
etEnergy.addTextChangedListener(tw);
etWeight.addTextChangedListener(tw);
etTime.addTextChangedListener(tw);
tvCals=(TextView) findViewById(R.id.tvCals);
}
Almost forgot to say that I'm using Android Studio 1.1.0 and app will be run on a physical device which is a HTC Butterfly that the Android version is 4.4.2 and the minimum API Level of the app is 14(IceCreamSandwich/4.0).
English is not my native language but I'll try hard to read any reply.
Thanks for your reading.
Also appreciates for your answering!

It seems that your EditText's are null. Please make sure that in activity_main layout you have EditText's with following ids: etEnergy, etWeight, etTime
And as a side note - you're not actually creating a new object of your myTextWatch and trying to pass null in addTextChangedListener(tw).

try this
protected EditText etEnergy,etWeight,etTime;
protected TextView tvCals;
//double t,a; //don't make any sense in following code.
TextWatch tw;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
etEnergy=(EditText) findViewById(R.id.etEnergy);
etWeight=(EditText) findViewById(R.id.etWeight);
etTime=(EditText) findViewById(R.id.etTime);
etEnergy.addTextChangedListener(tw);
etWeight.addTextChangedListener(tw);
etTime.addTextChangedListener(tw);
tvCals=(TextView) findViewById(R.id.tvCals);
}
tw= 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) {
etEnergy.removeTextChangedListener(this);
etWeight.removeTextChangedListener(this);
etTime.removeTextChangedListener(this);
Log.d("TextWatcher","TextChangedListenerRemoved");
etEnergy.addTextChangedListener(this);
etWeight.addTextChangedListener(this);
etTime.addTextChangedListener(this);
}
#Override
public void afterTextChanged(Editable s) {
}
};//end of class myTextWatch

android edittext onchange listener

I know a little bit about TextWatcher but that fires on every character you enter. I want a listener that fires whenever the user finishes editing. Is it possible? Also in TextWatcher I get an instance of Editable but I need an instance of EditText. How do I get that?
EDIT: the second question is more important. Please answer that.

First, you can see if the user finished editing the text if the EditText loses focus or if the user presses the done button (this depends on your implementation and on what fits the best for you).
Second, you can't get an EditText instance within the TextWatcher only if you have declared the EditText as an instance object. Even though you shouldn't edit the EditText within the TextWatcher because it is not safe.
EDIT:
To be able to get the EditText instance into your TextWatcher implementation, you should try something like this:
public class YourClass extends Activity {
private EditText yourEditText;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
yourEditText = (EditText) findViewById(R.id.yourEditTextId);
yourEditText.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {
// you can call or do what you want with your EditText here
// yourEditText...
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
public void onTextChanged(CharSequence s, int start, int before, int count) {}
});
}
}
Note that the above sample might have some errors but I just wanted to show you an example.

It was bothering me that implementing a listener for all of my EditText fields required me to have ugly, verbose code so I wrote the below class. May be useful to anyone stumbling upon this.
public abstract class TextChangedListener<T> implements TextWatcher {
private T target;
public TextChangedListener(T target) {
this.target = target;
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {}
#Override
public void afterTextChanged(Editable s) {
this.onTextChanged(target, s);
}
public abstract void onTextChanged(T target, Editable s);
}
Now implementing a listener is a little bit cleaner.
editText.addTextChangedListener(new TextChangedListener<EditText>(editText) {
#Override
public void onTextChanged(EditText target, Editable s) {
//Do stuff
}
});
As for how often it fires, one could maybe implement a check to run their desired code in //Do stuff after a given a

Anyone using ButterKnife. You can use like:
#OnTextChanged(R.id.zip_code)
void onZipCodeTextChanged(CharSequence zipCode, int start, int count, int after) {
}

I have done it using AutotextView:
AutotextView textView = (AutotextView) findViewById(R.id.autotextview);
textView.addTextChangedListener(new TextWatcher() {
#Override
public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
seq = cs;
}
#Override
public void beforeTextChanged(CharSequence s, int arg1, int arg2, int arg3) {
}
#Override
public void afterTextChanged(Editable arg0) {
new SearchTask().execute(seq.toString().trim());
}
});

myTextBox.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) {
TextView myOutputBox = (TextView) findViewById(R.id.myOutputBox);
myOutputBox.setText(s);
}
});

TextWatcher didn't work for me as it kept firing for every EditText and messing up each others values.
Here is my solution:
public class ConsultantTSView extends Activity {
.....
//Submit is called when I push submit button.
//I wanted to retrieve all EditText(tsHours) values in my HoursList
public void submit(View view){
ListView TSDateListView = (ListView) findViewById(R.id.hoursList);
String value = ((EditText) TSDateListView.getChildAt(0).findViewById(R.id.tsHours)).getText().toString();
}
}
Hence by using the getChildAt(xx) method you can retrieve any item in the ListView and get the individual item using findViewById. And it will then give the most recent value.

As far as I can think bout it, there's only two ways you can do it. How can you know the user has finished writing a word? Either on focus lost, or clicking on an "ok" button. There's no way on my mind you can know the user pressed the last character...
So call onFocusChange(View v, boolean hasFocus) or add a button and a click listener to it.

The Watcher method fires on every character input.
So, I built this code based on onFocusChange method:
public static boolean comS(String s1,String s2){
if (s1.length()==s2.length()){
int l=s1.length();
for (int i=0;i<l;i++){
if (s1.charAt(i)!=s2.charAt(i))return false;
}
return true;
}
return false;
}
public void onChange(final EditText EdTe, final Runnable FRun){
class finalS{String s="";}
final finalS dat=new finalS();
EdTe.setOnFocusChangeListener(new OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {dat.s=""+EdTe.getText();}
else if (!comS(dat.s,""+EdTe.getText())){(new Handler()).post(FRun);}
}
});
}
To using it, just call like this:
onChange(YourEditText, new Runnable(){public void run(){
// V V YOUR WORK HERE
}}
);
You can ignore the comS function by replace the !comS(dat.s,""+EdTe.getText()) with !equal function. However the equal function itself some time work not correctly in run time.
The onChange listener will remember old data of EditText when user focus typing, and then compare the new data when user lose focus or jump to other input. If comparing old String not same new String, it fires the work.
If you only have 1 EditText, then u will need to make a ClearFocus function by making an Ultimate Secret Transparent Micro EditText 😸 outside the windows 😽 and request focus to it, then hide the keyboard via Import Method Manager.

In Kotlin Android EditText listener is set using,
val searchTo : EditText = findViewById(R.id.searchTo)
searchTo.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable) {
// you can call or do what you want with your EditText here
// yourEditText...
}
override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {}
override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {}
})

I have taken the solution from #RNGuy thanks for that!
And changed the listener a bit so now it will only accept integers by updating the textView.
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
public abstract class NumberChangedListener implements TextWatcher {
private final EditText target;
private final String defaultValue;
public NumberChangedListener(EditText target, int defaultValue) {
this.target = target;
this.defaultValue = defaultValue + "";
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {}
#Override
public void afterTextChanged(Editable s) {
this.onTextChanged(target, s);
}
private void onTextChanged(EditText target, Editable s) {
String input = s.toString();
String number = input.replaceAll("[^\\d]", "");
if (!number.equals(input)) {
target.setText(number);
return;
}
Integer integer;
try {
integer = Integer.valueOf(number);
} catch (NumberFormatException ignored) {
target.setText(defaultValue);
return;
}
if (!integer.toString().equals(number)) {
target.setText(integer.toString());
return;
}
onNumberChanged(integer);
}
public abstract void onNumberChanged(int value);
}
and use as
int defaultVal = 10;
mTextView.addTextChangedListener(new NumberChangedListener(mTextView, defaultVal) {
#Override
public void onNumberChanged(int value) {
// use the parsed int
}
});