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Android碎片空对象mNextAnim内部崩溃

javaandroidandroid-fragmentsandroid-studioback-stack
9

我正在开发的应用程序的用户遇到了崩溃问题。这是我从控制台得到的堆栈跟踪。

java.lang.NullPointerException: Attempt to write to field 'int android.support.v4.app.Fragment.mNextAnim' on a null object reference
at android.support.v4.app.BackStackRecord.popFromBackStack(BackStackRecord.java:924)
at android.support.v4.app.FragmentManagerImpl.popBackStackState(FragmentManager.java:1605)
at android.support.v4.app.FragmentManagerImpl$4.run(FragmentManager.java:532)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)

这种崩溃只会在使用Galaxy Note3或Galaxy S4的5.x版本的用户中发生，至少我们只收到了这些用户的报告，但情况很严重。它似乎发生在片段之间的转换或有时从相机返回时。以下是我的转换方法。

public void popBackStackToOr(String popBackFragmentName, String secondPopBackFragment)
{
    int backStackId = 0;
    int backStackCount = getSupportFragmentManager().getBackStackEntryCount();

    List<Fragment> fragments = getSupportFragmentManager().getFragments();

    for (int k = (backStackCount - 1); k > 0; k--)
    {
        String aFragmentClass = fragments.get(k).getClass().toString();
        String[] splitList = aFragmentClass.split("\\.");
        aFragmentClass = splitList[splitList.length - 1];

        boolean firstOptionTrue  = aFragmentClass.equalsIgnoreCase(popBackFragmentName);
        boolean secondOptionTrue = aFragmentClass.equalsIgnoreCase(secondPopBackFragment);

        if ( (firstOptionTrue) || (secondOptionTrue) )
        {
            backStackId = getSupportFragmentManager().getBackStackEntryAt(k).getId();
            break;
        }
    }

    getSupportFragmentManager().popBackStack(backStackId, android.support.v4.app.FragmentManager.POP_BACK_STACK_INCLUSIVE); //Immediate
}

public void popBackStackForReview(String popBackFragmentName)
{
    int backStackId = 0;
    int backStackCount = getSupportFragmentManager().getBackStackEntryCount();

    List<Fragment> fragments = getSupportFragmentManager().getFragments();

    for (int k = (backStackCount - 1); k > 0; k--)
    {
        String aFragmentClass = fragments.get(k).getClass().toString();
        String[] splitList = aFragmentClass.split("\\.");
        aFragmentClass = splitList[splitList.length - 1];
        if (aFragmentClass.equalsIgnoreCase(popBackFragmentName))
        {
            backStackId = getSupportFragmentManager().getBackStackEntryAt(k).getId();
            break;
        }
    }

    getSupportFragmentManager().popBackStack(backStackId, android.support.v4.app.FragmentManager.POP_BACK_STACK_INCLUSIVE);
}

public void transitionToLoginPage()
{
    Fragment newFragment = new LoginPage();

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    transaction.replace(R.id.frame_container, newFragment);
    //transaction.addToBackStack(null);

    transaction.commitAllowingStateLoss();
}

public void transitionToNewScreen(Fragment newFragment, Bundle bundle)
{
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    if (currentFragment != null)
    {
        transaction.remove(currentFragment);
    }

    currentFragment = newFragment;

    if (bundle != null)
    {
        newFragment.setArguments(bundle);
    }

    transaction.replace(R.id.frame_container, newFragment);
    transaction.addToBackStack("dummy");

    transaction.commitAllowingStateLoss();
}

public void transitionToNewScreenAndEmptyStack(Fragment newFragment)
{
    getSupportFragmentManager().popBackStack(0, android.support.v4.app.FragmentManager.POP_BACK_STACK_INCLUSIVE);

    currentFragment = newFragment;

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.frame_container, newFragment);
    transaction.addToBackStack(null);
    transaction.commitAllowingStateLoss();
}

这些是应用程序中唯一进行过渡的方法。因此，我认为它来自这些方法之一。但是堆栈跟踪没有返回到我编写的任何代码，所以我不确定。我发现类似的问题称这是Android 5.x问题，并且没有修复。因此，任何帮助解决此问题都将是极好的。
你尝试过用commit()替换commitAllowingStateLoss()吗？ - user2641570
不，我还没有尝试过。我可以尝试替换它，看看会发生什么。 - sethprogrammer
这解决了问题，但对于旧设备来说会导致崩溃和其他问题。 - sethprogrammer
2个回答
19

这是因为你正在使用null值调用remove()、add()等方法。

请记住，replace() = remove()->add()一个接一个地进行。

4
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