Fragment报错 java.lang.IllegalStateException: Fragment already added: XXFragment{47ad471 #0 i

 java.lang.IllegalStateException: Fragment already added: GoodsDetailFragment{47ad471 #0 id=0x7f0903f9 android:switcher:2131297273:0}
        at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1882)
        at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:762)
        at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2580)
        at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2367)
        at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2322)
        at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2199)
        at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:651)
        at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:145)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1236)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1084)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)
        at android.view.View.measure(View.java:18827)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:901)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18827)
        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:716)
        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:462)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5954)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
        at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
        at android.view.View.measure(View.java:18827)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2136)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1248)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1484)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6064)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:860)
        at android.view.Choreographer.doCallbacks(Choreographer.java:672)
        at android.view.Choreographer.doFrame(Choreographer.java:608)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:846)
        at android.os.Handler.handleCallback(Handler.java:742)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:157)
        at android.app.ActivityThread.main(ActivityThread.java:5653)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:746)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)

有时候会报这样的错但是又找不到add的原因，那这种情况下一般是相关联的布局问题中出错了，也不一定是当前Fragment，可能是它的子Fragment也会提示这样的错误，所以可以优先从布局排查入手。