java 在 Android 中使用 SimpleCursorAdapter 填充列表视图

Populate listview using SimpleCursorAdapter in Android

提问by javaMonkey

I know this question has been asked and answered before, but I have followed multiple tutorials to no avail.

我知道这个问题之前已经被问过和回答过，但我遵循了多个教程都无济于事。

I just thought if I put my code up maybe someone could help and point me in the right direction. I am not going to lie, I am a massive noob at this but am loving it so far (well, up to this point anyway). All that is happening is when I load the activity, it just force closes with the following error message:

我只是想如果我把我的代码放在一起，也许有人可以帮助我指出正确的方向。我不会撒谎，我在这方面是个大菜鸟，但到目前为止我很喜欢它（好吧，无论如何，到目前为止）。发生的所有事情是当我加载活动时，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

So, here it is. My database query is:

所以，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);    
}

Then my list view code:

然后我的列表视图代码：

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());
        }
    });
}

And last but not least, here is my XML:

最后但并非最不重要的是，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>

采纳答案by Squonk

The error you are getting is most likely because you're trying to embed a TextView into a ListView...

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>

Remove the TextView from the ListView and then try the following...

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);

This uses the pre-defined Android android.R.layout.simple_list_item_1and android.R.id.text1

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

回答by Jens Zalzala

Your to and from need to be the same length. You don't need to include _id in the 'from' array. Note that you still need to have _id in your cursor.

你的往返需要是相同的长度。您不需要在 'from' 数组中包含 _id。请注意，您仍然需要在光标中包含 _id。