I want to write some debugging output to the log to review it with logcat.
If I write something to System.out this is already displayed in logcat.
What is the clean way to write to the log and add levels and tags to my output?
android.util.Log. It lets you write to the log with various log levels, and you can specify different tags to group the output.
Log.w("myApp", "no network");
will output a warning with the tag myApp and the message no network.
The Tag is just used to easily find your output, because the Output of LogCat can be sometimes very long. You can define somewhere in your class:
private static final String TAG = "myApp";
and use it when debugging
Log.v(TAG, "did something");
You can apply as well a Filter to only search for the tag.