初始化时片段的布局字段为NULL

Question

我有将数据传递给片段的问题.它在生产中的所有时间都有0.1%的崩溃.让我们说100k开放活动它发生了100次.它看起来并不常见,但它非常困扰我,我认为我在使用数据进行片段初始化时出错了.问题是,我只创建了一次片段,而其他所有时间我都需要将数据传递给它们我正在做下一步:myFragmentInstance.setData(Object someData);发生崩溃是因为它告诉片段中的那些视图元素未找到并且它们是NULL,但如果我没有重新创建它们,一切都应该没问题.我没有旋转手机,也没有足够的内存.它发生在网络重新连接上,因为在网络重新连接时,我将服务器获取新数据,然后将新数据设置为我的片段.我有我使用的两个片段的字段照片,maby你们中的一些人知道这些数据可以告诉崩溃时片段的状态.我正在使用库ButterKnife初始化片段和活动的字段,而不是初始化它findById,maby它有一些影响或没有？

这里是简单项目的链接(在github上只有这个问题): https ://github.com/yozhik/Reviews/tree/master/app/src/main/java/com/ylet/sr/review

描述:

CollapsingActivity- 活动Collapsing AppBarLayout.它将一个或两个片段加载到" fragment_content_holder"中,并且必须TabLayout在视图寻呼机中的片段之间切换.

在活动方法onCreate()- 我只是模拟对server(loadData)的请求,并且当加载一些假数据时 - 我在第一次调用时在视图寻呼机中显示片段 - 我正在创建新的TabMenuAdapter扩展FragmentPagerAdapter,用片段填充它并保存到实例的链接.在下一个调用中 - 我不会从头开始创建片段,只是用新数据填充它们.

MenuFragment1, MenuFragment1 - 两个片段.MenuFragment1- 有方法public void setupData(SomeCustomData data),设置新数据,不在网络重新连接上重新创建片段.

NetworkStateReceiver - 收听网络更改并发送通知.

TabMenuAdapter - 只是简单的类来保存片段.

05-11 18:11:05.088 12279-12279/com.myProjectName E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.myProjectName, PID: 12279
    java.lang.IllegalStateException: Fatal Exception thrown on Scheduler.
        at io.reactivex.android.schedulers.HandlerScheduler$ScheduledRunnable.run(HandlerScheduler.java:111)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5268)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
        at com.yozhik.myProjectName.view.fragments.MyFinalTermsFragment.setupMyInformation(MyFinalTermsFragment.java:145)
        at com.yozhik.myProjectName.view.fragments.MyFinalTermsFragment.setupWithData(MyFinalTermsFragment.java:133)
        at com.yozhik.myProjectName.view.activity.MyFinalActivity.onDataLoaded(MyFinalActivity.java:742)
        at com.yozhik.myProjectName.presenter.MyFinalPresenter$1.onNext(MyFinalPresenter.java:55)
        at com.yozhik.myProjectName.presenter.MyFinalPresenter$1.onNext(MyFinalPresenter.java:47)
        at io.reactivex.internal.operators.observable.ObservableObserveOn$ObserveOnObserver.drainNormal(ObservableObserveOn.java:200)
        at io.reactivex.internal.operators.observable.ObservableObserveOn$ObserveOnObserver.run(ObservableObserveOn.java:252)
        at io.reactivex.android.schedulers.HandlerScheduler$ScheduledRunnable.run(HandlerScheduler.java:109)
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:135) 
        at android.app.ActivityThread.main(ActivityThread.java:5268) 
        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:902) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) 
05-11 18:11:07.953 2155-3877/? E/WifiStateMachine: Did not find remoteAddress {192.168.200.1} in /proc/net/arp
05-11 18:11:07.966 2155-3877/? E/WifiStateMachine: WifiStateMachine CMD_START_SCAN source -2 txSuccessRate=3800.62 rxSuccessRate=4732.06 targetRoamBSSID=any RSSI=-68
05-11 18:11:07.967 2155-3877/? E/WifiStateMachine: WifiStateMachine L2Connected CMD_START_SCAN source -2 2324, 2325 -> obsolete
05-11 18:11:08.021 2155-3896/? E/ConnectivityService: Unexpected mtu value: 0, wlan0
05-11 18:11:08.579 13514-13366/? E/WakeLock: release without a matched acquire!

由于data_1_txt有时为NULL ,因此在方法setupData中崩溃的片段.

public class MenuFragment1 extends Fragment {

    public SomeCustomData transferedDataFromActivity;
    private TextView data_1_txt;

    public static MenuFragment1 newInstance(SomeCustomData data) {
        Log.d("TEST", "MenuFragment1.newInstance");
        MenuFragment1 fragment = new MenuFragment1();

        Bundle args = new Bundle();
        args.putSerializable("DATA_FROM_ACTIVITY", data);
        fragment.setArguments(args);

        return fragment;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d("TEST", "MenuFragment1.onCreate");

        if (getArguments() != null) {
            this.transferedDataFromActivity = (SomeCustomData) getArguments().getSerializable("DATA_FROM_ACTIVITY");
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        Log.d("TEST", "MenuFragment1.onCreateView");
        View v = inflater.inflate(R.layout.menu_fragment_1, container, false);
        data_1_txt = (TextView) v.findViewById(R.id.data_1_txt);

        setupInOnCreateView();

        return v;
    }

    protected void setupInOnCreateView() {
        Log.d("TEST", "MenuFragment1.setupInOnCreateView");
        //initialization of all view elements of layout with data is happens here.
        setupData(transferedDataFromActivity);
    }

    public void setupData(SomeCustomData data) {
        Log.d("TEST", "MenuFragment1.setupData");
        this.transferedDataFromActivity = data;
        if (transferedDataFromActivity != null) {
            data_1_txt.setText(transferedDataFromActivity.Name);
        }
    }
}

片段布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/green"
    android:orientation="vertical">

    <TextView
        android:id="@+id/data_1_txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/yellow"
        android:text="Test"
        android:textSize="20sp" />

    <include layout="@layout/description_layout" />

</LinearLayout>

Answer 1

根据我的经验，如果片段中存在错误，通常是因为片段的预加载viewpager，TabMenu所以我所做的并建议您做的是检查片段是否对用户可见，如果是，则获取数据和其他事情所以这是我的代码：

public class Fragment1 extends Fragment {
boolean visible = false;
public static Fragment1 newInstance() {
    return new Fragment1();
}
@Override
public View onCreateView(LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    if (visible && isResumed()) {
        onResume();
    } else if (visible) {
        getMyData();
    }
    return rootView;
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    visible = isVisibleToUser;
    if (isVisibleToUser) {
        getMyData();
    }
    else {
    }
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
}
}

这样，如果视图尚未创建并且对用户片段不可见，则不会执行任何操作。

希望这可以帮助。