为什么我使用 StickyGridHeaders 库得到 NullPointerException，而其他人使用同一个库就好了？

Question

我在 StickyGridHeaders library, while others (this) and (this 中得到一个 NullPointerException) 似乎正在使用它，没有这个例外。

我可能还应该提到我在我的项目中添加了库的 .jar 文件，因为我使用 Eclipse（而不是 Android Studio）。

我该如何解决这个问题？

部分Logcat:

...
06-24 08:42:22.419: E/AndroidRuntime(1495): FATAL EXCEPTION: main
06-24 08:42:22.419: E/AndroidRuntime(1495): java.lang.NullPointerException
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.tonicartos.widget.stickygridheaders.StickyGridHeadersSimpleArrayAdapter.getHeaderView(StickyGridHeadersSimpleArrayAdapter.java:93)
...

SSCCE:

MainActivity.java:

public class MainActivity extends Activity {
    private static final String TAG = MainActivity.class.getSimpleName();

    private StickyGridHeadersGridView mainGridView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
        mainGridView = (StickyGridHeadersGridView) findViewById(R.id.mainActivity_gridView);

        final String[] dataArray = {
                "A",
                "B",
                "C",
                "D",
                "E",
                "F",
                "G",
                "H",
                "I",
                "J",
        };

        StickyGridHeadersSimpleArrayAdapter<String> stickyGridHeadersSimpleAdapter = 
                new StickyGridHeadersSimpleArrayAdapter<String>(
                getApplicationContext(), dataArray, R.layout.header,
                R.layout.item);
        mainGridView.setAdapter(stickyGridHeadersSimpleAdapter);

        mainGridView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Log.i(TAG, "Item labelled " + dataArray[position] + "clicked.");
            }
        });

    }
}

activity_main.xml:

<RelativeLayout 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="${relativePackage}.${activityClass}" >

    <com.tonicartos.widget.stickygridheaders.StickyGridHeadersGridView android:id="@+id/mainActivity_gridView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|center_horizontal"
            android:background="#90000000"
            android:gravity="center"
            android:horizontalSpacing="10dp"
            android:verticalSpacing="10dp"
            android:numColumns="4"
            android:stretchMode="columnWidth" />

</RelativeLayout>

header.xml:

<?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="wrap_content"
    android:orientation="vertical" >

    <TextView android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="10dp"
        android:textColor="#fff" />


    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#ff33b5e5" >
    </FrameLayout>

</LinearLayout>

item.xml:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:padding="10dp"
    android:textColor="#fff" />

编辑：

06-24 08:42:22.415: W/dalvikvm(1495): threadid=1: thread exiting with uncaught exception (group=0xa62ad288)
06-24 08:42:22.419: E/AndroidRuntime(1495): FATAL EXCEPTION: main
06-24 08:42:22.419: E/AndroidRuntime(1495): java.lang.NullPointerException
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.tonicartos.widget.stickygridheaders.StickyGridHeadersSimpleArrayAdapter.getHeaderView(StickyGridHeadersSimpleArrayAdapter.java:93)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.tonicartos.widget.stickygridheaders.StickyGridHeadersSimpleAdapterWrapper.getHeaderView(StickyGridHeadersSimpleAdapterWrapper.java:57)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.tonicartos.widget.stickygridheaders.StickyGridHeadersBaseAdapterWrapper.getView(StickyGridHeadersBaseAdapterWrapper.java:172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.AbsListView.obtainView(AbsListView.java:2267)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.GridView.onMeasure(GridView.java:1030)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.tonicartos.widget.stickygridheaders.StickyGridHeadersGridView.onMeasure(StickyGridHeadersGridView.java:822)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.View.measure(View.java:15172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.View.measure(View.java:15172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.View.measure(View.java:15172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.View.measure(View.java:15172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.View.measure(View.java:15172)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.Choreographer.doCallbacks(Choreographer.java:555)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.Choreographer.doFrame(Choreographer.java:525)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.os.Handler.handleCallback(Handler.java:615)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.os.Handler.dispatchMessage(Handler.java:92)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.os.Looper.loop(Looper.java:137)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at android.app.ActivityThread.main(ActivityThread.java:4745)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at java.lang.reflect.Method.invokeNative(Native Method)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at java.lang.reflect.Method.invoke(Method.java:511)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
06-24 08:42:22.419: E/AndroidRuntime(1495):     at dalvik.system.NativeStart.main(Native Method)
06-24 08:47:22.611: I/Process(1495): Sending signal. PID: 1495 SIG: 9

Answer 1

我刚刚让它在 Eclipse 中运行。这是我所做的：

在 Eclipse 中创建一个名为 StickyGridHeaders 的新项目。使它成为库项目并打包 com.tonicartos.widget.stickygridheaders 在里面。不创造任意 Activity.
在包中创建六个class，并给它们取相同的名字 classes here.
打开每个 classes here 并将代码复制到在您的 Eclipse 库项目中对应 class。保存它们。
现在，在您实际的 SSCCE 项目中，在 header.xml 和 item.xml 中，在 TextView 元素中，添加 android:id="@android:id/item1" 属性。感谢 Mike M. 对这一步的评论。
从您的 SSCCE 项目中，删除您拥有的库的 .jar 文件之前包括在内。
在您的 SSCCE 项目中，像您一样添加此项目从您的工作区添加任何其他项目。

原因：

在您的堆栈跟踪中，提到了 StickyGridHeadersSimpleArrayAdapter 的第 93 行，但该行在 class 的 Github 版本中是空白的。根据getView()方法提到了StickyGridHeadersBaseAdapterWrapper的第172行，但这行在getItemViewType()方法中，也没有调用getView()。

所以我得出结论，.jar 是该项目的先前版本..

为什么我使用 StickyGridHeaders 库得到 NullPointerException，而其他人使用同一个库就好了？

Why am I getting a NullPointerException using StickyGridHeaders library, while others are using the same library just fine?

android

gridview

nullpointerexception

android-gridview