TextWatcher events are being fired multiple times

问题

I have an annoying problem with TextWatcher. i've been searching the web but couldnt find anything. appreciate if someone could assist me.

For some reason the calls to the TextWatcher events upon one text change are erratic. sometimes they are being triggered once (like they should be), sometimes twice, and sometimes 3 times. have no idea why, the whole thing is very straight forward. also sometimes the Editable parameter on afterTextChanged() returns empty values in toString() and length().

code is below:

    private TextWatcher mSearchAddressTextChangeListener = 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) { }

        @Override
        public void afterTextChanged(Editable searchedAddress) {
           System.out.println("called multiple times.");   
        }
    };

inside afterTextChanged() (and the AsyncTask) im not making any change to the text or the EditText view.

i saw the question asked in Events of TextWatcher are being called twice, but im having the events triggered more (or less) than twice.

anyway, appreciate any help.

EDIT: I removed the content of afterTextChanged() cause this problem is happening even without my code. what leads me to believe this is a bug. The bug is occuring when a 'space' char is entered right after a regular char (event handlers are triggered twice) or when a 'space' char after a regular char is removed (backspace. event handlers are triggered 3 times). help will still be appreciated.

回答1:

I had the same kind of problem, when I pressed backspace with cursor at the end of a continuous text, afterTextChange was called 3 times: - The first time with the correct s value - The second time with a clear value - The third time with the correct value again

After having search a lot on the web, I tried to change my EditText inputType to

android:inputType="textNoSuggestions"

Don't ask me why, but it worked, afterTextChanged is now called only once.

回答2:

According to the developer pages for TextWatcher, if a change is made to the Editable within TextWatcher, it will trigger further calls to all the TextWatchers linked to that Editable. Now, clearly your code doesn't trigger this behaviour.

However, it is quite possible that if, for whatever reason, the system has a TextWatcher on the Editable, the situation you describe can occur. "Why", I hear you cry, "should this happen?"

First, the classic defence: there is no reason for it not to happen and, strictly, app code should be written to be resilient to it.

Second, I can't prove it, but I could well imagine that the code which handles layout of the displayed text within an EditText uses a TextWatcher to handle updating the display of the text on the screen. This code might insert control codes (which you aren't shown) into the Editable to ensure good line breaks and so on. It may even go round a loop a few times to get it right, and you might only get your first call after it has done all of its ...

EDIT

As per the comment by @Learn OpenGL ES, calling of a TextWatcher would be normal for things like autocorrect.

回答3:

boolean isOnTextChanged = false;

@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
    isOnTextChanged = true;
}

@Override
public void afterTextChanged(Editable quantity) {
    if (isOnTextChanged) {
        isOnTextChanged = false;
       //dosomething
    }

回答4:

u can use a boolean check, like:

    inputBoxNumberEt.addTextChangedListener(new TextWatcher() {

        boolean ignoreChange = false;

        @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 (!ignoreChange) {
              ///Do your checks                    
                ignoreChange = true;
                inputBoxNumberEt.setText(string);
                inputBoxNumberEt.setSelection(inputBoxNumberEt.getText().length());
                ignoreChange = false;
            }
        }
    });

回答5:

I tried all the solution answered on this question, none of those worked for me. But after some search I found this post. Using the RxJava to make the debounce worked well for me. Here goes my final solution:

Add RxJava dependencies in the Gradle file:

compile 'io.reactivex:rxandroid:1.0.1'
compile 'io.reactivex:rxjava:1.0.14'
compile 'com.artemzin.rxjava:proguard-rules:1.0.14.2'

Implement your subject:

PublishSubject<String> yourSubject = PublishSubject.create();
    yourSubject .debounce(100, TimeUnit.MILLISECONDS)
            .onBackpressureLatest()
            .subscribe(s -> {
                //Implements anything you want
            });

Use your subject in your TextWatcher:

TextWatcher myTextWatcher = 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) {
        yourSubject.onNext(s.toString()); //apply here your subject
    }

    @Override
    public void afterTextChanged(Editable s) {
    }
};

Add the TextWatcher in the EditText listener:

my_edit_text.addTextChangedListener(myTextWatcher);

回答6:

For me the below code worked. Please observe that boolean value has been changed after if condition loop in afterTextChanged method

        edittext.addTextChangedListener(new TextWatcher() 
        {
            boolean considerChange = false;

            public void beforeTextChanged(CharSequence cs, int start, int count, int after) {}

            public void onTextChanged(CharSequence cs, int start, int before, int count) {}

            public void afterTextChanged(Editable editable) 
            {
                if (considerChange) 
                { 
                    // your code here
                }
                considerChange = !considerChange; //see that boolean value is being changed after if loop
            }


        });

来源：https://stackoverflow.com/questions/17535415/textwatcher-events-are-being-fired-multiple-times

标签

android

android-layout

textwatcher