At times, even full stack traces with line numbers aren’t quite enough to pinpoint the bug. To give you even more insight, Crashlytics provides 4 logging mechanisms right out of the box: logging, custom keys, user information, and caught exceptions (see the Caught Exceptions page).

Custom Logging

Logged messages are associated with your crash data and are visible in the Crashlytics dashboard if you look at the specific crash itself.

We’ve built Crashlytics.log to help pinpoint issues. The recommended way to add custom logging to your app is:

Crashlytics.log(int priority, String tag, String msg);

In addition to writing to the next crash report, it will also write to to LogCat using android.util.Log.println(priority, tag, msg). If you don’t want to write to LogCat you should call

Crashlytics.log(msg);

which will only write to the Crashlytics crash report, e.g.:

Crashlytics.log(Log.ERROR, 
 		"MyApp", 
 		"Higgs-Boson detected! Bailing out..."); 

Custom Keys

Crashlytics allows you to associate arbitrary key/value pairs with your crash reports, which are viewable right from the Crashlytics dashboard. Setting keys are as easy as calling: Crashlytics.setString(key, value) or one of the related methods. Options are:

	void setBool(String key, boolean value); 

	void setDouble(String key, double value); 

	void setFloat(String key, float value); 

	void setInt(String key, int value); 

Re-setting the same key will update the value. Examples:

Crashlytics.setInt("current_level", 3);
Crashlytics.setString("last_UI_action", "logged_in");

Note: By default, Crashlytics currently supports a maximum of 64 key/value pairs. Once you reach this threshold, additional values are not saved.

User Information

You can use Crashlytics.setUserIdentifier to provide an ID number, token, or hashed value that uniquely identifies the end-user of your application without disclosing or transmitting any of their personal information. This value is displayed right in the Fabric dashboard.

void setUserIdentifier(String identifier); 

If you would like to take advantage of advanced user identifier features, you can additionally use both:

void setUserName(String name); 
void setUserEmail(String email);