android - 为什么当我设置 ListView 时应用程序崩溃？

Question

我正在尝试运行我在一本关于 ListView 的书中找到的示例。正如书中所述，我在 string.xml 文件中创建了 string-array，ListView 的布局在 list_item 中。 xml 在 res->layout 文件夹中。

问题是，当我运行 Activity 时，应用程序崩溃了。谁能告诉我错误在哪里？

代码 1:

public class ListViewTestActivity extends ListActivity {
/** Called when the activity is first created. */

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

    String[] c = getResources().getStringArray(R.array.cities);
    setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, c));
    }}

string.xml

<resources>

<string name="hello">Hello World, ListViewTestActivity!</string>
<string name="app_name">ListViewTest</string>

<string-array
        name="cities">
    <item>Bath</item>
    <item>Birmingham</item>
    <item>Bradford</item>
    <item>Brighton</item>
    <item>Bristol</item>
    <item>Cambridge</item>
    <item>Canterbury</item>
</string-array>

list_item.xml:

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textSize="28dip">
    </TextView>


</LinearLayout>

LogCat:

    05-05 22:45:16.018: E/ArrayAdapter(648): You must supply a resource ID for a TextView
05-05 22:45:16.048: E/AndroidRuntime(648): FATAL EXCEPTION: main
05-05 22:45:16.048: E/AndroidRuntime(648): java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:347)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ArrayAdapter.getView(ArrayAdapter.java:323)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.AbsListView.obtainView(AbsListView.java:1430)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ListView.makeAndAddView(ListView.java:1745)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ListView.fillDown(ListView.java:670)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ListView.fillFromTop(ListView.java:727)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ListView.layoutChildren(ListView.java:1598)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.AbsListView.onLayout(AbsListView.java:1260)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.View.layout(View.java:7175)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.View.layout(View.java:7175)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.LinearLayout.onLayout(LinearLayout.java:1047)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.View.layout(View.java:7175)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.View.layout(View.java:7175)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.ViewRoot.performTraversals(ViewRoot.java:1140)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.os.Looper.loop(Looper.java:130)
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.app.ActivityThread.main(ActivityThread.java:3683)
05-05 22:45:16.048: E/AndroidRuntime(648):  at java.lang.reflect.Method.invokeNative(Native Method)
05-05 22:45:16.048: E/AndroidRuntime(648):  at java.lang.reflect.Method.invoke(Method.java:507)
05-05 22:45:16.048: E/AndroidRuntime(648):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-05 22:45:16.048: E/AndroidRuntime(648):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-05 22:45:16.048: E/AndroidRuntime(648):  at dalvik.system.NativeStart.main(Native Method)
05-05 22:45:16.048: E/AndroidRuntime(648): Caused by: java.lang.ClassCastException: android.widget.LinearLayout
05-05 22:45:16.048: E/AndroidRuntime(648):  at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:340)

Answer 1

如果您对行项目使用该特定布局，则将 id 分配给 TextView 并将其传递到适配器的构造函数中，让适配器知道在哪里放置数据:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/text"  
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:textSize="28dip">
</TextView>

在你的 Activity 中:

setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, R.id.text, c));