android.app.FragmentManager.beginTransaction()‘：尝试调用虚拟方法的android.app.FragmentTransaction android.app.FragmentTransaction

Question

当我试图取消FragmentDialog时，我的应用程序有时会崩溃。

这是日志：

Process: com.xxx, PID: 9981
java.lang.RuntimeException: Error receiving broadcast Intent { act=xxxx flg=0x10 (has extras) } in xxxxxx
    at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:893)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5438)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.FragmentTransaction android.app.FragmentManager.beginTransaction()' on a null object reference
    at android.app.DialogFragment.dismissInternal(DialogFragment.java:296)
    at android.app.DialogFragment.dismissAllowingStateLoss(DialogFragment.java:277)
    at xxxxx.updateStatus(BaseAppCompatActivity.java:96)
    at xxxxx.access$000(BaseAppCompatActivity.java:43)
    at xxxxx$1.onReceive(BaseAppCompatActivity.java:79)
    at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:883)

xxxxx.updateStatus(BaseAppCompatActivity.java:96)

这一行是试图取消一个DialogFragment：

mDialogFragment.dismissAllowingStateLoss();

DialogFragment在我的活动中。

private SimpleBlockedDialogFragment mDialogFragment = SimpleBlockedDialogFragment.newInstance();

所以mDialogFragment不是空的。

我展示这样的对话：

FragmentTransaction ft = getFragmentManager().beginTransaction();
mDialogFragment.updateMessage("xxx");
mDialogFragment.show(ft, "block_dialog");

并取消这样的对话框：

mDialogFragment.dismissAllowingStateLoss();

有时，我只显示对话一次，但驳回不止一次。但我不认为那会引起车祸。

下面是dismissInternal在DialogFragment中的函数：

void dismissInternal(boolean allowStateLoss) {
    if (mDismissed) {
        return;
    }
    mDismissed = true;
    mShownByMe = false;
    if (mDialog != null) {
        mDialog.dismiss();
        mDialog = null;
    }
    mViewDestroyed = true;
    if (mBackStackId >= 0) {
        getFragmentManager().popBackStack(mBackStackId,
                FragmentManager.POP_BACK_STACK_INCLUSIVE);
        mBackStackId = -1;
    } else {
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.remove(this);
        if (allowStateLoss) {
            ft.commitAllowingStateLoss();
        } else {
            ft.commit();
        }
    }
}

日志告诉我，getFragmentManager()返回null。我不知道为什么会这样。

如何正确地驳回FragmentDialog？

更新：

我尝试了android.support.v4.app.FragmentTransaction，但仍然得到了一个例外。

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentTransaction android.support.v4.app.FragmentManager.beginTransaction()' on a null object reference
    at android.support.v4.app.DialogFragment.dismissInternal(DialogFragment.java:196)
    at android.support.v4.app.DialogFragment.dismissAllowingStateLoss(DialogFragment.java:177)

帮助~

Answer 1

试试getSupportFragmentManager().beginTransaction();，这可能会有帮助。