DialogFragment.dismiss与NullPointerException崩溃 [英] DialogFragment.dismiss crashing with NullPointerException

问题描述

我正在做一些背景工作，并在执行此操作时显示DialogFragment.一旦完成工作并调用了相关的回调，我便关闭了该对话框.当我这样做时，我在android源代码中遇到了由NPE引起的崩溃:

I'm doing some background work and showing a DialogFragment while I do that. Once my work is done and the relevant callback is invoked, I dismiss the dialog. When I do, I get a crash caused by a NPE in the android source, here:

void dismissInternal(boolean allowStateLoss) {
        if (mDialog != null) {
            mDialog.dismiss();
            mDialog = null;
        }
        mRemoved = 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();
            }
        }
    }

具体在以下行: FragmentTransaction ft = getFragmentManager().beginTransaction();

推荐答案

当您像Sogger所说的那样调用show()之前调用dismiss()时，也会发生这种情况.

This may also occur when you call dismiss() before you have called show() like Sogger said.

在构造Dialog对象之后但不显示对话框之前，如果可以传递(mDialog！= null)并发生NullPointerException.

After Dialog object is constructed but before dialog is not showed, if (mDialog != null) can be passed and NullPointerException will occur.

当您检查mDialog是否为空时，

When you check if mDialog is null or not,

if (mDialog != null) {
    mDialog.dismiss();
    mDialog = null;
}

添加更多类似如下的条件，

Add more conditions like below,

if ((mDialog != null) && mDialog.isAdded() && mDialog.isResumed()) {
    mDialog.dismiss();
    mDialog = null;
}

我认为mDialog.iwego()条件可能就足够了...

I think that mDialog.isAdded() condition might be enough...

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