java - 在 Android 中使用 SimpleCursorAdapter 填充 ListView

Question

我知道这个问题之前已经被问过和回答过，但是我已经按照多个教程进行操作都无济于事。

我只是想，如果我把我的代码放上去，也许有人可以帮助我并为我指明正确的方向。我不想撒谎，我在这方面是个菜鸟，但到目前为止我很喜欢它(好吧，到目前为止)。所发生的一切是当我加载 Activity 时，它只是强制关闭并显示以下错误消息:

06-14 20:04:08.162: ERROR/AndroidRuntime(17605): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.magic8/com.example.magic8.AnswerList}: java.lang.UnsupportedOperationException: addView(View, LayoutParams) is not supported in AdapterView

所以，就在这里。我的数据库查询是:

public Cursor fetchAnswersList() {
    return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, "answer"}, 
    null, null, null, null, null, null);    
}

然后我的 ListView 代码:

public class AnswerList extends Activity {

private Context context;
private DatabaseManager mDbHelper;


public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.answerlist);        

    Cursor answers = mDbHelper.fetchAnswersList();
    startManagingCursor(answers);

    ListView answerList=(ListView)findViewById(R.id.answerList);    

    String[] from = new String[] {"_id", "answer"};
    int[] to = new int[] {R.id.answerItem};
    SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(context, R.layout.list_item, answers, from, to);
    answerList.setAdapter(cursorAdapter);

    answerList.setOnItemClickListener(
        new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view,
            int position, long id) {
          // When clicked, show a toast with the TextView text
          setToast("Answer: " + ((TextView) view).getText());
        }
    });
}

最后但同样重要的是，这是我的 XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">
    <LinearLayout 
        android:id="@+id/addAnswerForm" 
        android:layout_height="wrap_content" 
        android:layout_width="match_parent" 
        android:orientation="horizontal">
        <EditText 
        android:id="@+id/addAnswer"
        android:layout_weight="1" 
        android:layout_height="wrap_content" 
        android:layout_width="wrap_content">
            <requestFocus></requestFocus>
        </EditText>
        <Button 
        android:text="Add" 
        android:id="@+id/addAnswer_btn" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content">
        </Button>
     </LinearLayout>
     <LinearLayout 
        android:id="@+id/answers" 
        android:layout_height="match_parent" 
        android:layout_width="match_parent">
        <ListView 
        android:layout_weight="1" 
        android:layout_height="wrap_content" 
        android:id="@+id/answerList" 
        android:layout_width="match_parent">
        <TextView 
            android:id="@+id/answerItem" 
            android:layout_height="match_parent" 
            android:layout_width="match_parent">
        </TextView>
    </ListView>
     </LinearLayout>   

</LinearLayout>

Answer 1

您遇到的错误很可能是因为您试图将 TextView 嵌入到 ListView 中...

<ListView 
    android:layout_weight="1" 
    android:layout_height="wrap_content" 
    android:id="@+id/answerList" 
    android:layout_width="match_parent">
    <TextView 
        android:id="@+id/answerItem" 
        android:layout_height="match_parent" 
        android:layout_width="match_parent">
    </TextView>
</ListView>

从 ListView 中删除 TextView，然后尝试以下操作...

String[] from = new String[] {"answer"};
int[] to = new int[] {android.R.id.text1};
SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(context, android.R.layout.simple_list_item_1, answers, from, to);

这使用预定义的 Android android.R.layout.simple_list_item_1 和 android.R.id.text1