即使使用ProGuard（或R8）删除了Log.d（）中的语句，仍然可以执行吗？

Question

I have the following statement in my proguard-rules.pro to strip out logging in the production apk:

-assumenosideeffects class android.util.Log {
    public static boolean isLoggable(java.lang.String, int);
    public static int v(...);
    public static int i(...);
    public static int w(...);
    public static int d(...);
    public static int e(...);
}

This has the effect of removing statements like:

Log.d(TAG, "setup finished");

Now let's consider the following statement:

Log.d(TAG, "setup finished with status " + client.getStatus());

My assumption until now was that this Log.d() statement would be stripped out and therefore that client.getStatus() would never get called.

Specifically, if client happens to be null then my assumption had been that there would be no NullPointerException .

But now I'm not so sure. Perhaps the compiler looks at the above statement more like the following:

int status = client.getStatus();
Log.d(TAG, "setup finished with status " + status);

Now the client.getStatus() statement is executed and NullPointerException may result.

What is the actual situation?

Note: I'm actually now using R8 rather than ProGuard.

Answer 1

OK so this came as a surprise to me, and possibly to others (@Antoniossss), but it seems that statements executed inside a Log.d() are executed despite ProGuard/R8 being configured to remove all Log.d() statements.

So, even with ProGuard/R8 being configured to remove all Log.d() statements, the following will result in a NullPointerException :

String myString = null;
Log.d(TAG, "myString length: " + myString.length());

So, in future I will remember to check these Log statements more carefully when reviewing my code to find the source of a NullPointerException from my Developer Console, and not just pass over them assuming that they cannot have been the cause.