最好的办法是在onAttach被调用时保持活动引用，并在任何需要的地方使用活动引用。

@Override
public void onAttach(Context context) {
    super.onAttach(activity);
    mContext = context;
}

@Override
public void onDetach() {
    super.onDetach();
    mContext = null;
}

在onActivityCreated()中调用getActivity()方法

The other answers that suggest keeping a reference to the activity in onAttach are just suggesting a bandaid to the real problem. When getActivity returns null it means that the Fragment is not attached to the Activity. Most commonly this happens when the Activity has gone away due to rotation or the Activity being finished but the Fragment still has some kind of callback listener registered preventing it from being garbage collected. When the listener gets called if you need to do something with the Activity but the Activity is gone there isn't much you can do. In your code you should just check getActivity() != null and if it's not there then don't do anything. If you keep a reference to the Activity that is gone you are preventing the Activity from being garbage collected. Any UI things you might try to do won't be seen by the user. I can imagine some situations where in the callback listener you want to have a Context for something non-UI related, in those cases it probably makes more sense to get the Application context. Note that the only reason that the onAttach trick isn't a big memory leak is because normally after the callback listener executes it won't be needed anymore and can be garbage collected along with the Fragment, all its View's and the Activity context. If you setRetainInstance(true) there is a bigger chance of a memory leak because the Activity field will also be retained but after rotation that could be the previous Activity not the current one.

最好的办法是在onAttach被调用时保持活动引用，并在任何需要的地方使用活动引用。

@Override
public void onAttach(Context context) {
    super.onAttach(activity);
    mContext = context;
}

@Override
public void onDetach() {
    super.onDetach();
    mContext = null;
}

请按照以下步骤操作。我想这会对你有帮助。

private boolean isVisibleToUser = false;
private boolean isExecutedOnce = false;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View root = inflater.inflate(R.layout.fragment_my, container, false);
    if (isVisibleToUser && !isExecutedOnce) {
        executeWithActivity(getActivity());
    }
    return root;
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    this.isVisibleToUser = isVisibleToUser;
    if (isVisibleToUser && getActivity()!=null) {
        isExecutedOnce =true;
        executeWithActivity(getActivity());
    }
}


private void executeWithActivity(Activity activity){
    //Do what you have to do when page is loaded with activity

}

PJL是对的。 我采纳了他的建议，我是这样做的:

为fragment定义的全局变量: attachingActivityLock = new Object(); private boolean syncVariable = false; 实现

@Override onAttach(Activity Activity) { super.onAttach(活动); synchronized (attachingActivityLock) { syncVariable = true; attachingActivityLock.notifyAll (); ｝ ｝

3.我在线程中包装了我的函数，在那里我需要调用getActivity()，因为如果它将在主线程上运行，我将用步骤4阻塞线程。onAttach()将永远不会被调用。

    Thread processImage = new Thread(new Runnable() {

        @Override
        public void run() {
            processImage();
        }
    });
    processImage.start();

4所示。在我的函数中，我需要调用getActivity()，我使用这个(在调用getActivity()之前)

    synchronized (attachingActivityLock) {
        while(!syncVariable){
            try {
                attachingActivityLock.wait();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

如果你有一些UI更新，记得在UI线程上运行它们。我需要更新ImgeView，所以我做了:

image.post(new Runnable() {

    @Override
    public void run() {
        image.setImageBitmap(imageToShow);
    }
});