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使用SimpleCursorAdapter从SQL DB填充ListView时出错

simplecursoradapter android-sqlite android-studio

O'Kara · 技术社区 · 6 年前

所以,我试着编写一个程序,在其中我可以创建任务,在ListView中显示任务的名称和日期,然后在ListView中单击它们后简单地编辑它们

我在人口方面有一些问题。我需要使用simplecursoradapter来完成这个程序(作为我大学的作业)

这是我的populate函数,它在我的main活动中

 private void populate(){
    Cursor cursor = myDb.getAllRows();
    String[] backDB = new String[] {DBAdapter.COLUMN_NAME, DBAdapter.COLUMN_DATE};
    int[] toView = new int[] {R.id.textViewName, R.id.textViewDate};
    SimpleCursorAdapter myCursor;
    myCursor = new SimpleCursorAdapter(getBaseContext(), R.layout.row_layout, cursor, backDB,toView, 0);
    ListView myList = (ListView) findViewById(R.id.listViewTasks);
    myList.setAdapter(myCursor);
}

我认为它可能与SQL数据库有关,特别是getAllRows函数,因为在logcat中,我可以看到该行有问题:

 myCursor = new SimpleCursorAdapter(getBaseContext(), R.layout.row_layout, cursor, backDB,toView, 0);

这是我的getAllRows函数

 public Cursor getAllRows() {
    String query = "SELECT * FROM " + TABLE_NAME;
    Cursor c = db.rawQuery(query, null);
    c.moveToFirst();
    return c;
}

我的程序死机了,而且一直死机。

1 回复 | 直到 6 年前

MikeT 6 年前

在一猜测您的问题是因为您没有名为圣婴 ,在这种情况下,日志将包含以下内容:

06-07 10:53:53.957 1178-1178/so50635292.so50635292 E/AndroidRuntime: FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{so50635292.so50635292/so50635292.so50635292.MainActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
        at android.app.ActivityThread.access$600(ActivityThread.java:130)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4745)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
        at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:302)
        at android.widget.CursorAdapter.init(CursorAdapter.java:168)
        at android.widget.CursorAdapter.<init>(CursorAdapter.java:145)
        at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:91)
        at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:104)
        at so50635292.so50635292.MainActivity.populate(MainActivity.java:31)
        at so50635292.so50635292.MainActivity.onCreate(MainActivity.java:23)
        at android.app.Activity.performCreate(Activity.java:5008)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)Â 
        at android.app.ActivityThread.access$600(ActivityThread.java:130)Â 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)Â 
        at android.os.Handler.dispatchMessage(Handler.java:99)Â 
        at android.os.Looper.loop(Looper.java:137)Â 
        at android.app.ActivityThread.main(ActivityThread.java:4745)Â 
        at java.lang.reflect.Method.invokeNative(Native Method)Â 
        at java.lang.reflect.Method.invoke(Method.java:511)Â 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)Â 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)Â 
        at dalvik.system.NativeStart.main(Native Method)Â

相关部分是 java.lang.IllegalArgumentException: column '_id' does not exist

游标适配器需要此列,它还应该是rowid的别名。行的别名是定义为 ?? INTEGER PRIMARY KEY ,也可以对可选的、后续的、自动递增关键字进行编码。然而,一般情况下,它不应该因为有间接费用编码自动增量。

要解决此问题,可以在 onCreate 方法,然后删除应用程序的数据或卸载该应用程序,然后重新运行该应用程序。

您也可以在查询数据时通过更改

 String query = "SELECT * FROM " + TABLE_NAME;

到

String query = "SELECT rowid AS _id,* FROM " + TABLE_NAME;

注意以下假设您没有使用rowid编码