后退按钮返回2个活动而不是1个

Question

作为主题，当我按下按钮时，我的应用程序返回2个活动。这是活动的重写后退按钮：

@Override
public void onBackPressed() {
    if (mainNavMenu != null && mainNavMenu.getDrawerLayout().isDrawerOpen(GravityCompat.START)) {
        mainNavMenu.getDrawerLayout().closeDrawers();
        return;
    }
    super.onBackPressed();
}

这是按下按钮前的活动堆栈：

Task id #300
* TaskRecord{3470ba7b #300 A=com.package.example U=0 sz=3}
  userId=0 effectiveUid=u0a199 mCallingUid=u0a199 mCallingPackage=com.package.example
  affinity=com.package.example
  intent={act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.package.example/.view.SplashScreenActivity}
  realActivity=com.package.example/.view.SplashScreenActivity
  autoRemoveRecents=false isPersistable=true numFullscreen=3 taskType=0 mTaskToReturnTo=1
  rootWasReset=false mNeverRelinquishIdentity=true mReuseTask=false
  Activities=[ActivityRecord{d9eeb4e u0 com.package.example/.view.MainActivity t300}, ActivityRecord{2017cfc8 u0 com.package.example/.view.JobDetailsActivity t300}, ActivityRecord{3da3f636 u0 com.package.example/.view.WebActivity t300}]
  askedCompatMode=false inRecents=true isAvailable=true
  lastThumbnail=android.graphics.Bitmap@22f31098 lastThumbnailFile=/data/system/recent_images/300_task_thumbnail.png
  hasBeenVisible=true firstActiveTime=1517840356492 lastActiveTime=1517840356492 (inactive for 4s)
  * Hist #2: ActivityRecord{3da3f636 u0 com.package.example/.view.WebActivity t300}
      packageName=com.package.example processName=com.package.example
      launchedFromUid=10199 launchedFromPackage=com.package.example userId=0
      app=ProcessRecord{21ce55f9 17355:com.package.example/u0a199}
      Intent { cmp=com.package.example/.view.WebActivity (has extras) }
      frontOfTask=false task=TaskRecord{3470ba7b #300 A=com.package.example U=0 sz=3}
      taskAffinity=com.package.example
      realActivity=com.package.example/.view.WebActivity
      baseDir=/data/app/com.package.example-2/base.apk
      dataDir=/data/data/com.package.example
      stateNotNeeded=false componentSpecified=true mActivityType=0
      compat={480dpi} labelRes=0x7f0d001f icon=0x7f0c0000 theme=0x7f0e0007
      config={0 1.0 222mcc99mnc it_IT ldltr sw360dp w360dp h615dp 480dpi nrml long port finger -keyb/v/h -nav/h s.6}
      resultTo=ActivityRecord{2017cfc8 u0 com.package.example/.view.JobDetailsActivity t300} resultWho=null resultCode=1117
      taskDescription: iconFilename=null label="null" color=ffadd44b
      launchFailed=false launchCount=1 lastLaunchTime=-4s170ms
      haveState=false icicle=null
      state=RESUMED stopped=false delayedResume=false finishing=false
      keysPaused=false inHistory=true visible=true sleeping=false idle=true
      fullscreen=true noDisplay=false immersive=false launchMode=0
      frozenBeforeDestroy=false forceNewConfig=false
      mActivityType=APPLICATION_ACTIVITY_TYPE
      waitingVisible=false nowVisible=true lastVisibleTime=-3s325ms
  * Hist #1: ActivityRecord{2017cfc8 u0 com.package.example/.view.JobDetailsActivity t300}
      packageName=com.package.example processName=com.package.example
      launchedFromUid=10199 launchedFromPackage=com.package.example userId=0
      app=ProcessRecord{21ce55f9 17355:com.package.example/u0a199}
      Intent { cmp=com.package.example/.view.JobDetailsActivity (has extras) }
      frontOfTask=false task=TaskRecord{3470ba7b #300 A=com.package.example U=0 sz=3}
      taskAffinity=com.package.example
      realActivity=com.package.example/.view.JobDetailsActivity
      baseDir=/data/app/com.package.example-2/base.apk
      dataDir=/data/data/com.package.example
      stateNotNeeded=false componentSpecified=true mActivityType=0
      compat={480dpi} labelRes=0x7f0d001f icon=0x7f0c0000 theme=0x7f0e0007
      config={0 1.0 222mcc99mnc it_IT ldltr sw360dp w360dp h615dp 480dpi nrml long port finger -keyb/v/h -nav/h s.6}
      taskDescription: iconFilename=null label="null" color=ffadd44b
      launchFailed=false launchCount=1 lastLaunchTime=-33s92ms
      haveState=false icicle=null
      state=STOPPING stopped=false delayedResume=false finishing=false
      keysPaused=false inHistory=true visible=false sleeping=false idle=true
      fullscreen=true noDisplay=false immersive=false launchMode=0
      frozenBeforeDestroy=false forceNewConfig=false
      mActivityType=APPLICATION_ACTIVITY_TYPE
      waitingVisible=false nowVisible=false lastVisibleTime=-32s196ms
  * Hist #0: ActivityRecord{d9eeb4e u0 com.package.example/.view.MainActivity t300}
      packageName=com.package.example processName=com.package.example
      launchedFromUid=10199 launchedFromPackage=com.package.example userId=0
      app=ProcessRecord{21ce55f9 17355:com.package.example/u0a199}
      Intent { flg=0x10008000 cmp=com.package.example/.view.MainActivity (has extras) }
      frontOfTask=true task=TaskRecord{3470ba7b #300 A=com.package.example U=0 sz=3}
      taskAffinity=com.package.example
      realActivity=com.package.example/.view.MainActivity
      baseDir=/data/app/com.package.example-2/base.apk
      dataDir=/data/data/com.package.example
      stateNotNeeded=false componentSpecified=true mActivityType=0
      compat={480dpi} labelRes=0x7f0d001f icon=0x7f0c0000 theme=0x7f0e0007
      config={0 1.0 222mcc99mnc it_IT ldltr sw360dp w360dp h615dp 480dpi nrml long port finger -keyb/v/h -nav/h s.6}
      taskDescription: iconFilename=null label="null" color=ffadd44b
      launchFailed=false launchCount=0 lastLaunchTime=-2m18s969ms
      haveState=true icicle=Bundle[mParcelledData.dataSize=3876]
      state=STOPPED stopped=true delayedResume=false finishing=false
      keysPaused=false inHistory=true visible=false sleeping=false idle=true
      fullscreen=true noDisplay=false immersive=false launchMode=0
      frozenBeforeDestroy=false forceNewConfig=false
      mActivityType=APPLICATION_ACTIVITY_TYPE
      waitingVisible=false nowVisible=false lastVisibleTime=-2m18s47ms

Running activities (most recent first):
  TaskRecord{3470ba7b #300 A=icom.package.example U=0 sz=3}
    Run #2: ActivityRecord{3da3f636 u0 icom.package.example/.view.WebActivity t300}
    Run #1: ActivityRecord{2017cfc8 u0 icom.package.example/.view.JobDetailsActivity t300}
    Run #0: ActivityRecord{d9eeb4e u0 icom.package.example/.view.MainActivity t300}

mResumedActivity: ActivityRecord{3da3f636 u0 icom.package.example/.view.WebActivity t300}
mLastPausedActivity: ActivityRecord{2017cfc8 u0 icom.package.example/.view.JobDetailsActivity t300}

有3项跑步活动 当我按下后退按钮时，这就是堆栈：

Task id #300
* TaskRecord{3470ba7b #300 A=icom.package.example U=0 sz=1}
  userId=0 effectiveUid=u0a199 mCallingUid=u0a199 mCallingPackage=icom.package.example
  affinity=icom.package.example
  intent={act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=icom.package.example/.view.SplashScreenActivity}
  realActivity=icom.package.example/.view.SplashScreenActivity
  autoRemoveRecents=false isPersistable=true numFullscreen=1 taskType=0 mTaskToReturnTo=1
  rootWasReset=false mNeverRelinquishIdentity=true mReuseTask=false
  Activities=[ActivityRecord{d9eeb4e u0 icom.package.example/.view.MainActivity t300}]
  askedCompatMode=false inRecents=true isAvailable=true
  lastThumbnail=android.graphics.Bitmap@22f31098 lastThumbnailFile=/data/system/recent_images/300_task_thumbnail.png
  hasBeenVisible=true firstActiveTime=1517840391154 lastActiveTime=1517840391154 (inactive for 4s)
  * Hist #0: ActivityRecord{d9eeb4e u0 icom.package.example/.view.MainActivity t300}
      packageName=icom.package.example processName=icom.package.example
      launchedFromUid=10199 launchedFromPackage=icom.package.example userId=0
      app=ProcessRecord{21ce55f9 17355:icom.package.example/u0a199}
      Intent { flg=0x10008000 cmp=icom.package.example/.view.MainActivity (has extras) }
      frontOfTask=true task=TaskRecord{3470ba7b #300 A=icom.package.example U=0 sz=1}
      taskAffinity=icom.package.example
      realActivity=icom.package.example/.view.MainActivity
      baseDir=/data/app/icom.package.example-2/base.apk
      dataDir=/data/data/icom.package.example
      stateNotNeeded=false componentSpecified=true mActivityType=0
      compat={480dpi} labelRes=0x7f0d001f icon=0x7f0c0000 theme=0x7f0e0007
      config={0 1.0 222mcc99mnc it_IT ldltr sw360dp w360dp h615dp 480dpi nrml long port finger -keyb/v/h -nav/h s.6}
      taskDescription: iconFilename=null label="null" color=ffadd44b
      launchFailed=false launchCount=0 lastLaunchTime=-2m54s257ms
      haveState=false icicle=null
      state=RESUMED stopped=false delayedResume=false finishing=false
      keysPaused=false inHistory=true visible=true sleeping=false idle=true
      fullscreen=true noDisplay=false immersive=false launchMode=0
      frozenBeforeDestroy=false forceNewConfig=false
      mActivityType=APPLICATION_ACTIVITY_TYPE
      waitingVisible=false nowVisible=true lastVisibleTime=-4s367ms

Running activities (most recent first):
  TaskRecord{3470ba7b #300 A=icom.package.example U=0 sz=1}
    Run #0: ActivityRecord{d9eeb4e u0 icom.package.example/.view.MainActivity t300}

mResumedActivity: ActivityRecord{d9eeb4e u0 icom.package.example/.view.MainActivity t300}
mLastPausedActivity: ActivityRecord{2017cfc8 u0 icom.package.example/.view.JobDetailsActivity t300 f}

正如你所看到的，只剩下一项活动了，我不知道为什么会这样。

Answer 1

private void moveBack() {
    //check for entry count
    if (fragmentManager != null && fragmentManager.getBackStackEntryCount() > 1) {
        fragmentManager.popBackStack();
    } else {
        finish();
    }
}