Question

我使用SimpleCursorAdapter创建了一个ListView来显示数据库内容。

我多次测试并发现SimpleCursorAdapter部分的初始化是个问题。（我看到了DB内容跟随Toast消息。）

布局和ID也与xml文件完全匹配......

你能告诉我可能是什么问题吗？（＆＃39;弃用＆＃39;会出问题吗？）

private void populateListViewFromDB() 
{
    Cursor cursor = dbAdapter.getAllRows();
    ListView myList = (ListView)findViewById(R.id.listView);
    startManagingCursor(cursor);
    String[] fromFieldNames = new String[]
            {dbAdapter.KEY_DATE, dbAdapter.KEY_CATEGORY, dbAdapter.KEY_COST,  
                 dbAdapter.KEY_EXPLANATION};
    int[] toViewIds = new int[]
            {R.id.textView1, R.id.textView2, R.id.textView3, R.id.textView4};
    /*
    SimpleCursorAdapter myCursorAdapter = 
            new SimpleCursorAdapter(
                    this,                               // Context
                    R.layout.cash_expense_list_layout,  // Row layout template
                    cursor,                             // cursor (set of DB records to map)
                    fromFieldNames,                     // DB Column names
                    toViewIds                           // View IDs to put information in
                    );

    //Set the adapter for the listView
    myList.setAdapter(myCursorAdapter); 
    */
    cursor.moveToFirst();
    // move to the next item each time
    while (cursor.moveToNext()) {
        // get string and column index from cursor
        String date = cursor
                .getString(cursor.getColumnIndex(dbAdapter.KEY_DATE));
        String category = cursor.getString(cursor
                .getColumnIndex(dbAdapter.KEY_CATEGORY));
        String explanation = cursor.getString(cursor
                .getColumnIndex(dbAdapter.KEY_EXPLANATION));
        int cost = cursor.getInt(cursor.getColumnIndex(dbAdapter.KEY_COST));

        Toast.makeText(this,
                "Date: " + date + "\n" + "Category: " + category + " Cost : " + cost,
                Toast.LENGTH_SHORT).show();
    }

下面是logcat

11-18 15:34:24.405: E/AndroidRuntime(2730): FATAL EXCEPTION: main
11-18 15:34:24.405: E/AndroidRuntime(2730): Process: com.example.money, PID: 2730
11-18 15:34:24.405: E/AndroidRuntime(2730): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.money/com.example.money.CashAnalysis}: java.lang.IllegalArgumentException: column '_id' does not exist
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread.access$800(ActivityThread.java:135)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.os.Handler.dispatchMessage(Handler.java:102)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.os.Looper.loop(Looper.java:136)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread.main(ActivityThread.java:5001)
11-18 15:34:24.405: E/AndroidRuntime(2730): at java.lang.reflect.Method.invokeNative(Native Method)
11-18 15:34:24.405: E/AndroidRuntime(2730): at java.lang.reflect.Method.invoke(Method.java:515)
11-18 15:34:24.405: E/AndroidRuntime(2730): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
11-18 15:34:24.405: E/AndroidRuntime(2730): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
11-18 15:34:24.405: E/AndroidRuntime(2730): at dalvik.system.NativeStart.main(Native Method)
11-18 15:34:24.405: E/AndroidRuntime(2730): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.widget.CursorAdapter.init(CursorAdapter.java:172)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.widget.CursorAdapter.<init>(CursorAdapter.java:120)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:52)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:78)
11-18 15:34:24.405: E/AndroidRuntime(2730): at com.example.money.CashAnalysis.populateListViewFromDB(CashAnalysis.java:35)
11-18 15:34:24.405: E/AndroidRuntime(2730): at com.example.money.CashAnalysis.onCreate(CashAnalysis.java:19)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.Activity.performCreate(Activity.java:5231)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-18 15:34:24.405: E/AndroidRuntime(2730): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
11-18 15:34:24.405: E/AndroidRuntime(2730): ... 11 more

Answer 1

不，弃用不会导致此问题。

此错误清楚地告诉您问题的确切原因 - 您的数据库不包含名为_id的列，但此列是必需的

11-18 15:34:24.405: E/AndroidRuntime(2730): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist

此行指向导致上述异常的代码库的确切行

11-18 15:34:24.405: E/AndroidRuntime(2730): at com.example.money.CashAnalysis.populateListViewFromDB(CashAnalysis.java:35)

有关为何需要此列的详细信息，请参阅this Android documentation，其中包含以下注释：

注意：要使用Cursor备份ListView，游标必须包含a 列名为_ID。因此，前面显示的查询检索“words”表的_ID列，即使是 ListView不显示它。这种限制也解释了为什么最多提供者为每个表都有一个_ID列。

SimpleCurosrAdapter不起作用

1 个答案: