我是Android的新手，我想创建一个应用程序来获取所有传入的数字并显示在列表中。 在第一次安装应用程序时运行但不显示传入的数字，当我们在安装后再次打开应用程序时会崩溃。
要在安装后运行应用程序，需要清除其数据（然后应用程序运行但不显示任何内容）
logcat的
1-10 11:03:19.141 10244-10244/nischayvaish.com.test1 E/CursorWindow: Failed to read row 0, column -1 from a CursorWindow which has 1 rows, 2 columns.
11-10 11:03:19.141 10244-10244/nischayvaish.com.test1 D/AndroidRuntime: Shutting down VM
11-10 11:03:19.142 10244-10244/nischayvaish.com.test1 E/AndroidRuntime: FATAL EXCEPTION: main
Process: nischayvaish.com.test1, PID: 10244
java.lang.RuntimeException: Unable to start activity ComponentInfo{nischayvaish.com.test1/nischayvaish.com.test1.MainActivity}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.database.CursorWindow.nativeGetLong(Native Method)
at android.database.CursorWindow.getLong(CursorWindow.java:511)
at android.database.CursorWindow.getInt(CursorWindow.java:578)
at android.database.AbstractWindowedCursor.getInt(AbstractWindowedCursor.java:69)
at nischayvaish.com.test1.MainActivity.readFromDb(MainActivity.java:60)
at nischayvaish.com.test1.MainActivity.onCreate(MainActivity.java:38)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
这是 MainActivity 类
private TextView tv1;
private RecyclerView recycler_view;
private RecyclerView.LayoutManager layoutManager;
private ArrayList<IncomingNumber> arrayList = new ArrayList<>();
private RecyclerAdapter adapter;
private BroadcastReceiver broadcastReceiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv1 = (TextView) findViewById(R.id.emptyTxt);
recycler_view = (RecyclerView) findViewById(R.id.recyclerView);
layoutManager = new LinearLayoutManager(this);
recycler_view.setLayoutManager(layoutManager);
recycler_view.setHasFixedSize(true);
adapter = new RecyclerAdapter(arrayList);
recycler_view.setAdapter(adapter);
readFromDb();
broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
readFromDb();
}
};
}
private void readFromDb() {
arrayList.clear();
DbHelper dbHelper = new DbHelper(this);
SQLiteDatabase database = dbHelper.getWritableDatabase();
Cursor cursor = dbHelper.readNumber(database);
if (cursor.getCount() > 0) {
while (cursor.moveToNext()) {
String number;
int id;
number = cursor.getString(cursor.getColumnIndex(DbContract.INCOMING_NUMBER));
id = cursor.getInt(cursor.getColumnIndex("id"));
arrayList.add(new IncomingNumber(id, number));
}
cursor.close();
dbHelper.close();
adapter.notifyDataSetChanged();
recycler_view.setVisibility(View.VISIBLE);
tv1.setVisibility(View.GONE);
}
}
@Override
protected void onResume() {
super.onResume();
registerReceiver(broadcastReceiver, new IntentFilter(DbContract.UPDATE_UI_FILTER));
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(broadcastReceiver);
}
这是 DbHelper.class
public class DbHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "numberDb";
private static final int DATABASE_VERSION =2;
private static final String CREATE = "CREATE TABLE " + DbContract.TABLE_NAME + "(ID INTEGER PRIMARY KEY AUTOINCREMENT," + DbContract.INCOMING_NUMBER + " TEXT);";
private static final String DROP_TABLE = "drop table if exists " + DbContract.TABLE_NAME;
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(DROP_TABLE);
onCreate(db);
}
public void saveNumber(String number, SQLiteDatabase database) {
ContentValues contentValues = new ContentValues();
contentValues.put(DbContract.INCOMING_NUMBER, number);
Log.e(number,"incoming nuumber");
database.insert(DbContract.TABLE_NAME, null, contentValues);
}
public Cursor readNumber(SQLiteDatabase database) {
String[] projection = {"id", DbContract.INCOMING_NUMBER};
return (database.query(DbContract.TABLE_NAME, projection, null, null, null, null, null));
}
DbContract.class
public static final String TABLE_NAME = "incomingInfo";
public static final String INCOMING_NUMBER = "incomingNumber";
public static final String UPDATE_UI_FILTER = "nischayvaish.com.test1.UPDATE_UI";
答案 0 :(得分：0)
如果没有对代码进行详细分析，以下语句会导致错误：
id = cursor.getInt(cursor.getColumnIndex("id"));
这是因为游标找不到名为id
返回给定列名的从零开始的索引，如果列不存在，则返回-1。如果您希望该列存在，请使用getColumnIndexOrThrow（String），这将使错误更加清晰。
结合jibrahim的回答，你对database.query的调用可能是错误的，应该引导你使用代码。
答案 1 :(得分：0)
我认为问题是getColumnIndex方法区分大小写，因此您应该使用getColumnIndex("id")
getColumnIndex("ID")
所以 readDB 方法可以是： -
private void readFromDb() {
arrayList.clear();
DbHelper dbHelper = new DbHelper(this);
SQLiteDatabase database = dbHelper.getWritableDatabase();
Cursor cursor = dbHelper.readNumber(database);
if (cursor.getCount() > 0) {
while (cursor.moveToNext()) {
String number;
int id;
number = cursor.getString(cursor.getColumnIndex(DbContract.INCOMING_NUMBER));
id = cursor.getInt(cursor.getColumnIndex("ID")); //<<<<<<<<
arrayList.add(new IncomingNumber(id, number));
}
cursor.close();
dbHelper.close();
adapter.notifyDataSetChanged();
recycler_view.setVisibility(View.VISIBLE);
tv1.setVisibility(View.GONE);
}
}
备注的
`//＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt; '表示更改的行
如果光标为空/有0行，你应该关闭光标，所以cursor.close()真的应该关闭，因此dbHelper.close()应该在if (cursor.getCount() > 0) {....}之外/之后构造。