Hilt: More meaningful error messages

First of all, Hilt looks like a really promising project, keep up the good work!

One feature I would like to see is more meaningful error messages at run time and compile time. For instance, one error I always seem to get is:

Caused by: java.lang.ClassCastException: com.mypackage.DaggerMainApplication_HiltComponents_ApplicationC$ActivityRetainedCImpl$ActivityCImpl cannot be cast to com.com.mypackage.MyActivity_GeneratedInjector

This runtime exception basically means that there is an error in the dependency graph meaning something can’t be injected, but it would be nice to know what exactly.

Even better, if this problem could be caught and displayed at compile time, then fantastic 😃

kind regards, goldy1992

[ChanSek]

@Chang-Eric, is it expected to occur in below scenario?

:ui-component module - ‘com.android.library’ :profile module - ‘com.android.library’

implementation project(':ui-component')

:app module - ‘com.android.application’

implementation project(':ui-component')
implementation project(':profile')

In the above project, I have my Application class in :ui-component module.

@HiltAndroidApp
class CommonApp : Application()

And my Activity is in :profile module.

@AndroidEntryPoint
class ProfileActivity : BaseActivity(R.layout.activity_profile)

But when I run this app, I get below exception at runtime.

Process: com..., PID: 11338
    java.lang.RuntimeException: Unable to start activity ComponentInfo{.../....ProfileActivity}: java.lang.ClassCastException: ....DaggerCommonApp_HiltComponents_ApplicationC$ActivityRetainedCImpl$ActivityCImpl cannot be cast to ...ProfileActivity_GeneratedInjector
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2666)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6123)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
     Caused by: java.lang.ClassCastException: ....DaggerCommonApp_HiltComponents_ApplicationC$ActivityRetainedCImpl$ActivityCImpl cannot be cast to ...ProfileActivity_GeneratedInjector
        at ....Hilt_ProfileActivity.inject(Hilt_ProfileActivity.java:56)
        at ....Hilt_ProfileActivity.onCreate(Hilt_ProfileActivity.java:31)
        at ....ProfileActivity.onCreate(ProfileActivity.kt:25)
        at android.app.Activity.performCreate(Activity.java:6723)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2619)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727) 
        at android.app.ActivityThread.-wrap12(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:154) 
        at android.app.ActivityThread.main(ActivityThread.java:6123) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779) 

What could go wrong here? And why it’s a runtime error instead of compile time?

[martipello]

i just got an error and all it said was [Hilt] lol