Question

完整的堆栈仅包含android核心代码：

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean androidx.fragment.app.FragmentManagerImpl.isDestroyed()' on a null object reference
    at androidx.fragment.app.Fragment.performDetach(Fragment.java:2844)
    at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1033)
    at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1237)
    at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:434)
    at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2075)
    at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1865)
    at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1820)
    at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1726)
    at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6669)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

在主要活动中替换片段时会发生：

Runnable mPendingRunnable = new Runnable() {
            @Override
            public void run() {
                FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                fragmentTransaction.replace(R.id.frame, fragment);
                fragmentTransaction.commitAllowingStateLoss();
            }
        };

Answer 1

在模块的gradle中，我通过还原对其进行了修复

到

implementation 'androidx.appcompat:appcompat:1.1.0-beta01'

（上述关于childFragmentManager的答案没有帮助。）

Answer 2

我在myFragment.onDetach中找到了一段导致此问题的代码：

这是Getting the error "Java.lang.IllegalStateException Activity has been destroyed" when using tabs with ViewPager

的一种解决方法

        try {
            Field childFragmentManager = Fragment.class.getDeclaredField("mChildFragmentManager");
            childFragmentManager.setAccessible(true);
            childFragmentManager.set(this, null);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }

现在，在androidx中，不需要此解决方法。

Answer 3

我的基本片段中有这段代码

   try {
            val childFragmentManager = androidx.fragment.app.Fragment::class.java.getDeclaredField(
                    "mChildFragmentManager"
            )
            childFragmentManager.isAccessible = true
            childFragmentManager.set(this, null)
        } catch (e: NoSuchFieldException) {
            e.printStackTrace()
        } catch (e: IllegalAccessException) {
            e.printStackTrace()
        }

删除此代码后，崩溃已修复。

Answer 4

最近几天我一直在努力解决这个问题，最后我找到了解决方案。在这里我正在使用gradle

implementation 'androidx.constraintlayout:constraintlayout:1.1.2'

然后我用这段代码替换了我的片段。

 getActivity().getSupportFragmentManager().beginTransaction().detach(new    KiKorbo()).replace(R.id.calendar1, caldroidFragment).attach(caldroidFragment)
            .addToBackStack(null).commit();

这里KiKorbo.java是我的父片段，我替换了caldroidFragment。

Answer 5

在我的模块的 gradle 中，我通过恢复修复了它

implementation 'androidx.appcompat:appcompat:1.2.5'

到

implementation 'androidx.appcompat:appcompat:1.1.0'

迁移到AndroidX之后，应用程序因尝试在null ref上调用androidx.fragment.app.FragmentManagerImpl.isDestroyed（）而崩溃

5 个答案: