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Question

我尝试运行我的应用程序，但是在setAdapter（listAdapter）操作中遇到空指针异常。

主要活动Java代码

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Assigning main activity name for drawing
    setContentView(R.layout.activity_time);
    // Find the ListView resource and assign to ListView Object created
    ExpandableListView mainListView = (ExpandableListView) findViewById(R.id.textClock);
    // Initialize adapter with data by parsing JSON
    listAdapter = new TwocolumnAdapter(this, parseJSONString(readFile()), headersList);
    //Saving the reference to prepare new adapter when reload is needed
    object = this;
    // Set the ArrayAdapter as the ListView's adapter.
    mainListView.setAdapter(listAdapter);
}

主要活动XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="fill_parent" tools:context=".Time" android:background="@color/accent_material_dark" android:orientation="vertical">
<ExpandableListView android:layout_width="fill_parent" android:layout_height="wrap_content" android:id="@+id/textClock" android:layout_gravity="center_vertical" android:format24Hour="@android:string/yes" />

我搜索了几个SO帖子，交叉检查了ID等，尝试了所有解决方案，但无法解决这个问题。

任何建议或指示都受到高度赞赏。

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错误记录

12-18 00:36:59.609  19893-19893/sudharshanapps.clock E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: sudharshanapps.clock, PID: 19893
    java.lang.RuntimeException: Unable to start activity ComponentInfo{sudharshanapps.clock/sudharshanapps.clock.Time}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
            at android.app.ActivityThread.access$800(ActivityThread.java:139)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at sudharshanapps.clock.Time.onCreate(Time.java:264)
            at android.app.Activity.performCreate(Activity.java:5248)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
            at android.app.ActivityThread.access$800(ActivityThread.java:139)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

看起来问题是Layout-v17文件夹中的activity_time.xml。这是将用于API 17及更高版本的布局。看起来在这种情况下它实际上是加载这个xml而不是你期望的那个。尝试删除它或使其与active_time.xml的主要版本相同

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">
    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/mainListView" >
    </ListView>
</LinearLayout>

可扩展列表视图的setAdapter操作上的空指针异常

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1 个答案: