There are two Activities in my app:.
They are both in default LAUNCH MODE, which according to my understanding should be STANDARD mode.
Step 1: Now I start MainActivity by adb shell am start -n com.study.launch/.MainActivity command and the task stack becomes:
* [0] MainAcitivty
This is normal, because as expected, a new instance of MainActivity is created.
Step 2: Then I start SecondActivity with the command adb shell am start -n com.study.launch/.SecondActivity and the task stack becomes:
* [1] SecondAcitivty
* [0] MainAcitivty
This is normal, because as expected, a new instance of SecondActivity is created, and because Affnity defaults to the package name of the app, it is put into the same task, although the NEW TASK FLAG is set when am start.
Step 3: I then start SecondActivity again with the adb shell am start -n com.study.launch/.SecondActivity command and the task stack becomes:
* [2] SecondAcitivty
* [1] SecondAcitivty
* [0] MainAcitivity
This is normal, because as expected, a new instance of SecondActivity is created.
Step 4: Finally, I start MainActivity again with the command adb shell am start -n com.study.launch/.MainActivity. am gives me a warning as a result:
Starting: Intent { cmp=com.study.launch/.MainActivity }
Warning: Activity not started, intent has been delivered to currently running top-most instance.
Checking the task stack, it still holds:
* [2] SecondAcitivty
* [1] SecondAcitivty
* [0] MainAcitivity
My question: why is no new instance of MainActivity created?
At this point when dump activities, the task stack is:
ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities)
Display #0 (activities from top to bottom):
Stack #2970: type=standard mode=fullscreen
isSleeping=false
mBounds=Rect(0, 0 - 0, 0)
mResumedActivity: ActivityRecord{4165bf9 u0 com.study.launch/.SecondActivity t2970}
* Task{e640079 #2970 visible=true type=standard mode=fullscreen translucent=false A=10353:com.study.launch U=0 StackId=2970 sz=3}
mBounds=Rect(0, 0 - 0, 0)
mMinWidth=-1 mMinHeight=-1
userId=0 effectiveUid=u0a353 mCallingUid=2000 mUserSetupComplete=true mCallingPackage=com.android.shell mCallingFeatureId=null
affinity=10353:com.study.launch
intent={flg=0x10000000 cmp=com.study.launch/.MainActivity}
mActivityComponent=com.study.launch/.MainActivity
autoRemoveRecents=false isPersistable=true activityType=1
rootWasReset=false mNeverRelinquishIdentity=true mReuseTask=false mLockTaskAuth=LOCK_TASK_AUTH_PINNABLE
Activities=[ActivityRecord{bcbe940 u0 com.study.launch/.MainActivity t2970}, ActivityRecord{be1bac4 u0 com.study.launch/.SecondActivity t2970}, ActivityRecord{4165bf9 u0 com.study.launch/.SecondActivity t2970}]
askedCompatMode=false inRecents=true isAvailable=true
mRootProcess=ProcessRecord{f26596c 18860:com.study.launch/u0a353}
taskId=2970 stackId=2970
mHasBeenVisible=true
mResizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION mSupportsPictureInPicture=false isResizeable=true
lastActiveTime=932630195 (inactive for 208s)
* Hist #2: ActivityRecord{4165bf9 u0 com.study.launch/.SecondActivity t2970}
packageName=com.study.launch processName=com.study.launch
launchedFromUid=2000 launchedFromPackage=com.android.shell launchedFromFeature=null userId=0
app=ProcessRecord{f26596c 18860:com.study.launch/u0a353}
Intent { flg=0x10000000 cmp=com.study.launch/.SecondActivity }
rootOfTask=false task=Task{e640079 #2970 visible=true type=standard mode=fullscreen translucent=false A=10353:com.study.launch U=0 StackId=2970 sz=3}
taskAffinity=10353:com.study.launch
mActivityComponent=com.study.launch/.SecondActivity
baseDir=/data/app/~~16sf25MRe03beHbyI0Sc3g==/com.study.launch-SSF_oypq9Ln-G52kGNzmdw==/base.apk
dataDir=/data/user/0/com.study.launch
stateNotNeeded=false componentSpecified=false mActivityType=standard
compat={560dpi} labelRes=0x7f090055 icon=0x7f080001 theme=0x7f0a000a
mLastReportedConfigurations:
mGlobalConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=undefined mAlwaysOnTop=undefined mRotation=ROTATION_0} s.61}
mOverrideConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
CurrentConfiguration={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
taskDescription: label="null" icon=null iconResource=/0 iconFilename=null primaryColor=fff5f5f5
backgroundColor=fffafafa statusBarColor=0 navigationBarColor=0
launchFailed=false launchCount=1 lastLaunchTime=-3m28s587ms
mHaveState=false mIcicle=null
state=RESUMED stopped=false delayedResume=false finishing=false
keysPaused=false inHistory=true setToSleep=false idle=true mStartingWindowState=STARTING_WINDOW_NOT_SHOWN
occludesParent=true noDisplay=false immersive=false launchMode=0
frozenBeforeDestroy=false forceNewConfig=false
mActivityType=standard
windows=[Window{ef30aec u0 com.study.launch/com.study.launch.SecondActivity}]
windowType=2 hasVisible=true
mOccludesParent=true mOrientation=-1
mVisibleRequested=true mVisible=true mClientVisible=true reportedDrawn=true reportedVisible=true
mNumInterestingWindows=1 mNumDrawnWindows=1 allDrawn=true lastAllDrawn=true)
startingData=null firstWindowDrawn=true mIsExiting=false
nowVisible=true lastVisibleTime=-3m28s54ms
resizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION
mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
* Hist #1: ActivityRecord{be1bac4 u0 com.study.launch/.SecondActivity t2970}
packageName=com.study.launch processName=com.study.launch
launchedFromUid=2000 launchedFromPackage=com.android.shell launchedFromFeature=null userId=0
app=ProcessRecord{f26596c 18860:com.study.launch/u0a353}
Intent { flg=0x10000000 cmp=com.study.launch/.SecondActivity }
rootOfTask=false task=Task{e640079 #2970 visible=true type=standard mode=fullscreen translucent=false A=10353:com.study.launch U=0 StackId=2970 sz=3}
taskAffinity=10353:com.study.launch
mActivityComponent=com.study.launch/.SecondActivity
baseDir=/data/app/~~16sf25MRe03beHbyI0Sc3g==/com.study.launch-SSF_oypq9Ln-G52kGNzmdw==/base.apk
dataDir=/data/user/0/com.study.launch
stateNotNeeded=false componentSpecified=false mActivityType=standard
compat={560dpi} labelRes=0x7f090055 icon=0x7f080001 theme=0x7f0a000a
mLastReportedConfigurations:
mGlobalConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=undefined mAlwaysOnTop=undefined mRotation=ROTATION_0} s.61}
mOverrideConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
CurrentConfiguration={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
taskDescription: label="null" icon=null iconResource=/0 iconFilename=null primaryColor=fff5f5f5
backgroundColor=fffafafa statusBarColor=0 navigationBarColor=0
launchFailed=false launchCount=0 lastLaunchTime=-4m48s99ms
mHaveState=true mIcicle=Bundle[mParcelledData.dataSize=1380]
state=STOPPED stopped=true delayedResume=false finishing=false
keysPaused=false inHistory=true setToSleep=false idle=true mStartingWindowState=STARTING_WINDOW_NOT_SHOWN
occludesParent=true noDisplay=false immersive=false launchMode=0
frozenBeforeDestroy=false forceNewConfig=false
mActivityType=standard
windows=[Window{4792473 u0 com.study.launch/com.study.launch.SecondActivity}]
windowType=2 hasVisible=true
mOccludesParent=true mOrientation=-1
mVisibleRequested=false mVisible=false mClientVisible=false reportedDrawn=false reportedVisible=false
mAppStopped=true
mNumInterestingWindows=1 mNumDrawnWindows=1 allDrawn=true lastAllDrawn=true)
startingData=null firstWindowDrawn=true mIsExiting=false
nowVisible=false lastVisibleTime=-4m47s573ms
resizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION
mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
* Hist #0: ActivityRecord{bcbe940 u0 com.study.launch/.MainActivity t2970}
packageName=com.study.launch processName=com.study.launch
launchedFromUid=2000 launchedFromPackage=com.android.shell launchedFromFeature=null userId=0
app=ProcessRecord{f26596c 18860:com.study.launch/u0a353}
Intent { flg=0x10000000 cmp=com.study.launch/.MainActivity }
rootOfTask=true task=Task{e640079 #2970 visible=true type=standard mode=fullscreen translucent=false A=10353:com.study.launch U=0 StackId=2970 sz=3}
taskAffinity=10353:com.study.launch
mActivityComponent=com.study.launch/.MainActivity
baseDir=/data/app/~~16sf25MRe03beHbyI0Sc3g==/com.study.launch-SSF_oypq9Ln-G52kGNzmdw==/base.apk
dataDir=/data/user/0/com.study.launch
stateNotNeeded=false componentSpecified=false mActivityType=standard
compat={560dpi} labelRes=0x7f090001 icon=0x7f080001 theme=0x7f0a000a
mLastReportedConfigurations:
mGlobalConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=undefined mAlwaysOnTop=undefined mRotation=ROTATION_0} s.61}
mOverrideConfig={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
CurrentConfiguration={1.0 ?mcc?mnc [zh_CN] ldltr sw411dp w411dp h659dp 560dpi nrml port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1440, 2560) mAppBounds=Rect(0, 0 - 1440, 2392) mWindowingMode=fullscreen mDisplayWindowingMode=fullscreen mActivityType=standard mAlwaysOnTop=undefined mRotation=ROTATION_0} s.1}
taskDescription: label="null" icon=null iconResource=/0 iconFilename=null primaryColor=fff5f5f5
backgroundColor=fffafafa statusBarColor=0 navigationBarColor=0
launchFailed=false launchCount=0 lastLaunchTime=-5m43s524ms
mHaveState=true mIcicle=Bundle[mParcelledData.dataSize=1380]
state=STOPPED stopped=true delayedResume=false finishing=false
keysPaused=false inHistory=true setToSleep=false idle=true mStartingWindowState=STARTING_WINDOW_REMOVED
occludesParent=true noDisplay=false immersive=false launchMode=0
frozenBeforeDestroy=false forceNewConfig=false
mActivityType=standard
windows=[Window{76c0bff u0 com.study.launch/com.study.launch.MainActivity}]
windowType=2 hasVisible=true
mOccludesParent=true mOrientation=-1
mVisibleRequested=false mVisible=false mClientVisible=false reportedDrawn=false reportedVisible=false
mAppStopped=true
mNumInterestingWindows=1 mNumDrawnWindows=1 allDrawn=true lastAllDrawn=true)
startingData=null firstWindowDrawn=true mIsExiting=false
nowVisible=false lastVisibleTime=-5m41s774ms
resizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION
mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
Also, I found that if the first start of the app (process start) is started by adb shell am start, then the problem can be reproduced.
If the first start of the app is a click start in the launcher, then the issue no longer reproduces.
When you launch an Activity, Android looks to see if there is already a task that has that Activity at the root of the task (it also compares some Intent flags, which in your case would also match). If it finds a match, it just assumes that you are trying to bring that task to the foreground, and it does just that: brings the existing task to the foreground without launching an instance of the Activity.
This is why, when you have a task in the background, and you tap the app icon on the HOME screen, the existing task is brought to the foreground instead of Android launching the first Activity again. This is also how Android brings another task to the foreground when you select something from the "recent task list". It just launches the root Activity again, which causes Android to find the existing task and bring it to the foreground.
Now usually, when the launcher (HOME screen) launches an app, it sets a few additional parameters in the Intent:
FLAG_ACTIVITY_NEW_TASKFLAG_ACTIVITY_RESET_TASK_IF_NEEDEDACTION_MAINCATEGORY_LAUNCHERso that when you launch the app again from the HOME screen, the Intent also has these values set so they will match the values from the original Intent. Since you are using ADB to launch activities, these flags won't be set. This doesn't exactly match what is going on in a real-world scenario, which is why you see some differences. Hope this helps!