On the emulator and most devices
System.out.println gets redirected to LogCat and printed using
Log.i(). This may not be true on very old or custom Android versions.
There is no console to send the messages to so the
System.out.println messages get lost. In the same way this happens when you run a “traditional” Java application with
Instead, you can use the Android
Log.d("MyApp","I am here");
You can then view the log either in the Logcat view in Eclipse, or by running the following command:
It’s good to get in to the habit of looking at logcat output as that is also where the Stack Traces of any uncaught Exceptions are displayed.
The first Entry to every logging call is the log tag which identifies the source of the log message. This is helpful as you can filter the output of the log to show just your messages. To make sure that you’re consistent with your log tag it’s probably best to define it once as a
static final String somewhere.
There are five one-letter methods in
Log corresponding to the following levels:
wtf()– What a Terrible Failure
Verbose should never be compiled into an application except during development. Debug logs are compiled in but stripped at runtime. Error, warning and info logs are always kept.