android – 在onSaveInstanceState中保存接口(Listener)

SaveInstanceState

对于像Integer,Long,String等其他数据都很好,我只需将它放入包中,并在再次调用onCreateView后将其取回.但我的片段也有听众如下,

public class SomeFragment extends Fragment {
    public interface SomeListener {
        public void onStartDoingSomething(Object whatItIsDoing, Date when);
        public void onDoneDoingTheThing(Object whatItDid, boolean result);
    }

    private SomeFragmentListener listener;
    private String[] args;

    public static SomeFragment getInstance(SomeListener _listener, String... _args) {
        SomeFragment sf = new SomeFragment();
        sf.listener = _listener
        sf.args = _args

        return sf;
    }

    // rest of the class

    // the example of where do I invoke the listener are
    // - onSetVisibilityHint
    // - When AsyncTask is done
    // - successfully download JSON
    // etc.
} 

如何让侦听器捆绑以便以后可以将其取回？

解决方法:

我最近刚刚找到了正确的方法,我想分享这个主题的未来读者.

保存片段监听器的正确方法不是保存它,而是在片段附加到活动时从活动请求.

public class TheFragment extends Fragment {
    private TheFragmentListener listener;

    @Override
    public void onAttach(Context context) {
        if (context instanceof TheFragmentContainer) {
            listener = ((TheFragmentContainer) context).onRequestListener();
        }
    }

    public void theMethod() {
        // do some task
        if (listener != null) {
            listener.onSomethingHappen();
        }
    }

    public interface TheFragmentContainer {
        public TheFragmentListener onRequestListener();
    }

    public interface TheFragmentListener {
        public void onSomethingHappen();
    }
}

>当片段附加到活动时,我们检查活动是否实现了TheFragmentContainer
>如果活动有,请从活动请求监听器.

标签：android,activity-lifecycle,fragment-lifecycle
来源： https://codeday.me/bug/20190517/1120634.html