How to use an Android Handler to update a TextView in the UI Thread?
Solution 1:
There are several ways to update your UI and modify a View
such as a TextView
from outside of the UI Thread. A Handler
is just one method.
Here is an example that allows a single Handler
respond to various types of requests.
At the class level define a simple Handler
:
private final static int DO_UPDATE_TEXT = 0;
private final static int DO_THAT = 1;
private final Handler myHandler = new Handler() {
public void handleMessage(Message msg) {
final int what = msg.what;
switch(what) {
case DO_UPDATE_TEXT: doUpdate(); break;
case DO_THAT: doThat(); break;
}
}
};
Update the UI in one of your functions, which is now on the UI Thread:
private void doUpdate() {
myTextView.setText("I've been updated.");
}
From within your asynchronous task, send a message to the Handler
. There are several ways to do it. This may be the simplest:
myHandler.sendEmptyMessage(DO_UPDATE_TEXT);
Solution 2:
You can also update UI thread from background thread in this way also:
Handler handler = new Handler(); // write in onCreate function
//below piece of code is written in function of class that extends from AsyncTask
handler.post(new Runnable() {
@Override
public void run() {
textView.setText(stringBuilder);
}
});