How to know the android textview is set with a text

Question

如果用文本设置了android textview，是否有任何回调被调用

Answer 1

add a TextWatcher to a TextView for watching text changes in TextView as:

TextView textView=(TextView)findViewById(R.id.txtview);
    textView.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) {

        }

        @Override
        public void afterTextChanged(Editable s) {

             //here you will get changed text in textview
        }
    }); 

Answer 2

另一种方法是：

if( TextView.getText().length() != 0) {}

Answer 3

You can simply check if your TextView has any text using the following:

TextView yourTextView = (TextView)findViewById(R.id.textViewID);
if(yourTextview.getText().toString().equals(""))
     //it is blank
else
     //it has text

Answer 4

我认为最好的方法是：

if(TextView.getText == null);

Answer 5

No. The only way to tell at runtime if user has set text from code is to create an instance

TextView tv = (TextView)findViewById(R.id.your_id)

and check if this text has text with getText() method and see if your initially textView has text.