在 SlidingTabLayout 的上下文中膨胀 RecyclerView

Question

我之前创建了一个运行良好的 RecyclerView 以及一个带有 ViewPager 的 SlidingTabLayout，它显示了一个简单的 TextView。

但我想将它们结合起来，RecyclerView 显示在每个选项卡下，但是这是我遇到麻烦的地方。

当我使用简单的 TextView 填充 ViewPager 时，MainActivity 中的相关代码如下所示：

公共静态类 MyFragment 扩展片段 { 私有TextView textView;

    public static MyFragment getInstance(int position) {
        MyFragment myFragment = new MyFragment();
        Bundle args = new Bundle();
        args.putInt("position", position);
        myFragment.setArguments(args);
        return myFragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View layout = inflater.inflate(R.layout.fragment_my, container, false);
        textView = (TextView) layout.findViewById(R.id.position);
        Bundle bundle = getArguments();
        if (bundle != null) {
            textView.setText("The Page Currently Selected " + bundle.getInt("position"));
        }
        return layout;
    }
}

当我尝试用我的 RecyclerView 替换 TextView 时，我按以下方式更改了上面的代码：

public static class MyFragment extends Fragment {

        public static MyFragment getInstance(int position) {
            MyFragment myFragment = new MyFragment();
            Bundle args = new Bundle();
            args.putInt("position", position);
            myFragment.setArguments(args);
            return myFragment;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
            View layout = inflater.inflate(R.layout.fragment_games, container, false);
           return layout;
        }
    }

如您所见，我刚刚使布局等于包含我的 RecyclerView 的膨胀布局。

正在膨胀的布局，fragment_games，如下所示：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.xxxxxxxxx.chessgame.Games_Fragment">

    <!-- TODO: Update blank fragment layout -->

    <android.support.v7.widget.RecyclerView
        android:id="@+id/gameList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    </android.support.v7.widget.RecyclerView>

</FrameLayout>

最后，stacktrace 看起来像这样：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView$LayoutManager.onMeasure(android.support.v7.widget.RecyclerView$Recycler, android.support.v7.widget.RecyclerView$State, int, int)' on a null object reference
            at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:1764)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.view.View.measure(View.java:17430)
            at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1456)
            at android.view.View.measure(View.java:17430)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:875)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
            at android.view.View.measure(View.java:17430)
            at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:851)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5463)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:430)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2560)
            at android.view.View.measure(View.java:17430)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2001)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1166)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1372)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
            at android.view.Choreographer.doCallbacks(Choreographer.java:580)
            at android.view.Choreographer.doFrame(Choreographer.java:550)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Answer 1

我认为对于RecyclerView，您必须至少设置 LayoutManager。

见link

你可以在实例化RecyclerView之后尝试设置LayoutManager之类的

recyclerView.setLayoutManager(new LinearLayoutManager(this));

注意确保您添加了行

com.android.support:recyclerview-v7:21.0.0

你的 build.gradle