There Is No Difference In Android Studio 2.3.3 Between Clean And Rebuild, So Why Have Both Options In Build Menu?

Why are Clean and Rebuild identical in AS 2.3.3 and why then are both options found in the Build menu? As explained here, there is no difference in AS 2.3.3 between Build > Clea

Solution 1:

I use clean to update R values while I'm in the middle of coding. I don't want to know that there are errors in my unfinished code, I just want the R file links to be current.

On the other hand Rebuild lists out all the errors.

So behind the scenes they may be the same, but the results are presented in different ways to the user.

Solution 2:

@Sam is correct. Looking ONLY at the Event log is pretty superficial since it only logs events, not details. Looking at the Gradle console clarifies it all:

Here's what Clean, even with an error in the code I'm compiling:

Executing tasks: 
[clean, :app:generateDebugSources, :app:mockableAndroidJar,
        :app:prepareDebugUnitTestDependencies,             
        :app:generateDebugAndroidTestSources,
        :app:compileDebugSources, :app:compileDebugUnitTestSources,
        :app:compileDebugAndroidTestSources]

Configuration on demand is an incubating feature.

Incremental java compilation is an incubating feature.
:clean:app:clean:app:    preBuild UP-TO-DATE
(MY NOTE ^^^^^^^^
:app:preDebugBuild UP-TO-DATE
:app:checkDebugManifest:app:preReleaseBuild UP-TO-DATE
:app:prepareComAndroidSupportAnimatedVectorDrawable2600Alpha1Library:app:prepareComAndroidSupportAppcompatV72600Alpha1Library:app:prepareComAndroidSupportConstraintConstraintLayout102Library:app:prepareComAndroidSupportSupportCompat2600Alpha1Library:app:prepareComAndroidSupportSupportCoreUi2600Alpha1Library:app:prepareComAndroidSupportSupportCoreUtils2600Alpha1Library:app:prepareComAndroidSupportSupportFragment2600Alpha1Library:app:prepareComAndroidSupportSupportMediaCompat2600Alpha1Library:app:prepareComAndroidSupportSupportV42600Alpha1Library:app:prepareComAndroidSupportSupportVectorDrawable2600Alpha1Library:app:prepareDebugDependencies:app:compileDebugAidl:app:compileDebugRenderscript:app:generateDebugBuildConfig:app:generateDebugResValues:app:generateDebugResources:app:mergeDebugResources:app:processDebugManifest:app:processDebugResources:app:generateDebugSources:app:mockableAndroidJar:app:preDebugUnitTestBuild UP-TO-DATE
:app:prepareDebugUnitTestDependencies:app:preDebugAndroidTestBuild UP-TO-DATE
:app:prepareComAndroidSupportTestEspressoEspressoCore222Library:app:prepareComAndroidSupportTestEspressoEspressoIdlingResource222Library:app:prepareComAndroidSupportTestExposedInstrumentationApiPublish05Library:app:prepareComAndroidSupportTestRules05Library:app:prepareComAndroidSupportTestRunner05Library:app:prepareDebugAndroidTestDependencies:app:compileDebugAndroidTestAidl:app:processDebugAndroidTestManifest:app:compileDebugAndroidTestRenderscript:app:generateDebugAndroidTestBuildConfig:app:generateDebugAndroidTestResValues:app:generateDebugAndroidTestResources:app:mergeDebugAndroidTestResources:app:processDebugAndroidTestResources:app:generateDebugAndroidTestSources

Rebuild does all that PLUS THE FOLLOWING IF there's an error in the code:

:app:incrementalDebugJavaCompilationSafeguard
:app:javaPreCompileDebug
:app:compileDebugJavaWithJavac
:app:compileDebugJavaWithJavac - isnot incremental (e.g. outputs have changed, no previous execution, etc.).

C:\Users\Dov\Desktop\SQhell\app\src\main\java\com\dslomer64\sqhell\MainActivity.java:221: error: not a statement
x       returntrue;
^
C:\Users\Dov\Desktop\SQhell\app\src\main\java\com\dslomer64\sqhell\MainActivity.java:221: error: ';' expected
x       returntrue;
 ^
2 errors

:app:compileDebugJavaWithJavac FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace optiontoget the stack trace. Run with --info or --debug optiontoget more log output.

BUILD FAILED

Total time: 16.398 secs

If there is NO error in the code, Rebuild does this:

:app:compileDebugNdk UP-TO-DATE
:app:compileDebugSources:app:incrementalDebugUnitTestJavaCompilationSafeguard UP-TO-DATE
:app:javaPreCompileDebugUnitTest:app:compileDebugUnitTestJavaWithJavac UP-TO-DATE
:app:processDebugJavaRes UP-TO-DATE
:app:processDebugUnitTestJavaRes UP-TO-DATE
:app:compileDebugUnitTestSources UP-TO-DATE
:app:incrementalDebugAndroidTestJavaCompilationSafeguard:app:javaPreCompileDebugAndroidTest:app:compileDebugAndroidTestJavaWithJavac:app:compileDebugAndroidTestNdk UP-TO-DATE
:app:compileDebugAndroidTestSources

BUILD SUCCESSFUL

Total time:26.83 secs

In any event, Build performs a Clean AND THEN COMPILES the code, terminating if errors are found (and listed); otherwise, doing a full compile.

So Clean DOES differ from Rebuild.

(This means some other posts, like the one listed in Question, have to be modified.)