DexOverflowException: Cannot fit requested classes in the main-dex file

Question

I have quite big multi module, multi flavor multidex project, but recently I got error when trying to do command line build (assemble{flavor}Release)

Message is:

Answer 1

For release build you should try to fix that with proguard. For debug you can try to fix it by excluding some classes from main dex file.

Add this to the application module

   import your.awesome.app.MainDexGenerator

   tasks.whenTaskAdded {
            if (it.name.contains('transformDexArchiveWithDexMergerFor') && it.name.contains('Debug')) {
                it.doFirst(new MainDexGenerator([
                        'io/reactivex/annotations',
                        'kotlin',
                        'com/fasterxml'
                        //....and other you think could work 
                ]))
            }
        }

you can find classes that gradle wants to add to main dex in: intermeditates/legacy_multidex_main_dex_list/. For example you can exclude unused models or something else, basically everything you don't need when Application class is starting. Do not forget to check that you didn't broke anything on API 19 or lower

set up buildSrc with build.gradle with groovy plugin.

At buildSrc/main/groovy/your/awesome/app add your action:

@CompileStatic
class MainDexGenerator implements Action {

    private static final String MAIN_DEX_FILE = 'mainDexList.txt'

    // list we want to exclude frome MainDex
    private List excludedList
    MainDexGenerator(List excludedPackages) {
        excludedList = excludedPackages;
    }

    @Override
    void execute(Task task) {
        for (File inputFile : task.inputs.files.files) {
            if (inputFile.absolutePath.endsWith(MAIN_DEX_FILE)) {
                List result = Files.lines(inputFile.toPath())
                        .filter { isNotMatch(it) }
                        .collect(Collectors.toList())
                Files.write(inputFile.toPath(), result, WRITE, TRUNCATE_EXISTING)
                break
            }
        }
    }

    private boolean isNotMatch(String line) {
        for (String item : excludedList) {
            if (line.contains(item)) {
                return false
            }
        }
        return true
    }
}

Too see the resulting method count you can use apkAnalyzer tool. Look for first dex.

Also you can try to refactor your code and extract some responsibilities from application class.

You can also try to increase minApi to 21.

This answer has some more details on the problem Too many classes in --main-dex-list, main dex capacity exceeded