Sooner or later you’ll have to deal with it. If you’re an html developer and you write also in javascript you’ll surely know the onchange event.

Unfortunately it’s a little bit tricky to find the same event on android.

The onChange event is helpful when you’ve to deal with the following things:

• Let the user know (in realtime) how many characters he typed.
• Let the user know (in realtime) how many remaining characters he is allowed to type.
• Make realtime processing of the content ( like sending it online and fetch some partial results of the partial typed edittext )

You’ve to implement your own instance of TextWatcher and let the edittext know that you want to be notified at each change by calling the method EditText.addTextChangedListener.

Below i will give you a simple example ( it’s written on the fly but you’ll understand the idea )

[sourcecode lang=”java”]
((EditText)findViewById(R.id.et_testo)).addTextChangedListener(new TextWatcher() {

public void afterTextChanged(Editable s) {
((TextView)findViewById(R.id.numcaratteri)).setText(String.format(getString(R.string.caratteri), s.length()));

}

public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub

}

public void onTextChanged(CharSequence s, int start, int before,
int count) {
// TODO Auto-generated method stub

}

});

[/sourcecode]