Deactivate any calls to Log before publishing: are there tools to do this?

Question

According to Google, I must "Deactivate any calls to Log methods in the source code" before publishing my Android app (section 4 of the publication checklist).

My open-source project is large and it is a pain to do it manually every time I release. Additionally, removing a Log line is potentially tricky, for instance:

if(condition)
  Log.d(LOG_TAG, "Something");
data.load();
data.show();

If I comment the Log line, then the condition applies to the next line, and chances are load() is not called. Are such situations rare enough that I can decide it should exist?

This is on the official checklist, so I guess many people do this on a regular basis.
So, is there a tool that removes all Log lines?
Preferably one that is not tricked by code like the above.

Answer 1

While waiting for a better solution, I just wrote those shell scripts:

Comment logs:

find . -name "*\.java" | xargs grep -l 'Log\.' | xargs sed -i '' -e 's/Log\./\/\/ Log\./g'

Uncomment logs:

find . -name "*\.java" | xargs grep -l 'Log\.' | xargs sed -i '' -e 's/\/\/ Log\./Log\./g'

To prevent any side-effect, new rules appear in our coding style guide:

• No structure (if, for, etc) without brackets.
• Each Log call must take only one line, and not share this line with anything else.

Answer 2

I suggest having a static boolean somewhere indicating whether or not to log:

class MyDebug {
  static final boolean LOG = true;
}

Then wherever you want to log in your code, just do this:

if (MyDebug.LOG) {
  if (condition) Log.i(...);
}

Now when you set MyDebug.LOG to false, the compiler will strip out all code inside such checks (since it is a static final, it knows at compile time that code is not used.)

For larger projects, you may want to start having booleans in individual files to be able to easily enable or disable logging there as needed. For example, these are the various logging constants we have in the window manager:

static final String TAG = "WindowManager";
static final boolean DEBUG = false;
static final boolean DEBUG_FOCUS = false;
static final boolean DEBUG_ANIM = false;
static final boolean DEBUG_LAYOUT = false;
static final boolean DEBUG_RESIZE = false;
static final boolean DEBUG_LAYERS = false;
static final boolean DEBUG_INPUT = false;
static final boolean DEBUG_INPUT_METHOD = false;
static final boolean DEBUG_VISIBILITY = false;
static final boolean DEBUG_WINDOW_MOVEMENT = false;
static final boolean DEBUG_ORIENTATION = false;
static final boolean DEBUG_APP_TRANSITIONS = false;
static final boolean DEBUG_STARTING_WINDOW = false;
static final boolean DEBUG_REORDER = false;
static final boolean DEBUG_WALLPAPER = false;
static final boolean SHOW_TRANSACTIONS = false;
static final boolean HIDE_STACK_CRAWLS = true;
static final boolean MEASURE_LATENCY = false;

With corresponding code like:

    if (DEBUG_FOCUS || DEBUG_WINDOW_MOVEMENT) Log.v(
        TAG, "Adding window " + window + " at "
        + (i+1) + " of " + mWindows.size() + " (after " + pos + ")");

Answer 3

I find a far easier solution is to forget all the if checks all over the place and just use ProGuard to strip out any Log.d() or Log.v() method calls when we call our Ant release target.

That way, we always have the debug info being output for regular builds and don't have to make any code changes for release builds. ProGuard can also do multiple passes over the bytecode to remove other undesired statements, empty blocks and can automatically inline short methods where appropriate.

For example, here's a very basic ProGuard config for Android:

-dontskipnonpubliclibraryclasses
-dontobfuscate
-forceprocessing
-optimizationpasses 5

-keep class * extends android.app.Activity
-assumenosideeffects class android.util.Log {
    public static *** d(...);
    public static *** v(...);
}

So you would save that to a file, then call ProGuard from Ant, passing in your just-compiled JAR and the Android platform JAR you're using.

See also the examples in the ProGuard manual.