addTextChangedListener() 是否仍在 Android api 中？

Question

I am using a book from 2013, Android How To Program 2 ^nd Edition by Deitel and Harvey, they are using a method addTextChangedListener() to set up the listener for the TextWatcer , is this method still in the api?

I can't find any info on it on the Android developer doc.

//set amountEditText's TextWatcher
EditText amountEditText=(EditText) findViewById(R.id.amountEditText);
amountEditText.addTextChangedListener(amountEditTextWatcher);

Answer 1

is this method still in the api

Yes, you inherit it from TextView , the superclass of EditText .

Answer 2

I am using a book from 2013, Android How To Program 2nd Edition by Deitel and Harvey, they are using a method addTextChangedListener() to set up the listener for the TextWatcher , is this method still in the API?

The code that you quoted in your question is calling addTextChangedListener on amountEditText which is an EditView object. In other words, it is setting the amountEditTextWatcher as the text watcher for the EditView ... like the comment says.

You don't set a listener for a watcher. A watcher is a kind of listener. You set a listener / watcher on (for example) a view.

So basically, the code in the book is not doing what you think.

And the reason that you can't find addTextChangedListener on TextWatcher is that that interface has never had such a method. It is a method on EditView inherited from TextView .

Answer 3

Yes, you can see this sample.

 yourEditText.addTextChangedListener(new TextWatcher() {  
      
                @Override  
                public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {  
                    System.out.println(cs); //This is your live editing text.
                }  
      
                @Override  
                public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {  
                    Toast.makeText(getApplicationContext(),"before text change",Toast.LENGTH_LONG).show();  
                }  
      
                @Override  
                public void afterTextChanged(Editable arg0) {  
                    Toast.makeText(getApplicationContext(),"after text change",Toast.LENGTH_LONG).show();  
                }  
            });