我是Android的SQLite数据库新手我想从数据库中获取特定数据，但我无法做到这一点它给了我以下错误，我添加了_id列但是它仍然提供相同的例外，这可能是我如何解决这个问题的原因？有什么我想念的吗？
java.lang.IllegalArgumentException: column '_id' does not exist at
android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:333)
at android.support.v4.widget.CursorAdapter.init(CursorAdapter.java:186)
at android.support.v4.widget.CursorAdapter.<init>(CursorAdapter.java:163)
at android.support.v4.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:99)
at android.support.v4.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:94)
at com.iz.PG.SummaryFragment.onCreateView(SummaryFragment.java:57)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5769)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
我的代码如下 - DBHelper.java
public class DBHelper extends SQLiteOpenHelper {
// Table Name
public static final String TABLE_NAME = "detailinfo";
// Table columns
public static final String id = "_id";
public static final String param1 = "param1";
public static final String param2 = "param2";
public static final String param3 = "param3";
public static final String param4 = "param4";
// Database Information
static final String DB_NAME = "test.db";
// database version
static final int DB_VERSION = 1;
// create query
private static final String CREATE_TABLE = "create table " + TABLE_NAME + "( "+id+" INTEGER PRIMARY KEY AUTOINCREMENT," + param1+ " TEXT, " + param2 + " TEXT,"+param3+" TEXT,"+param4+" TEXT);";
public DBHelper(Context context) {
super(context,DB_NAME ,null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String query = "drop table if exists"+TABLE_NAME;
db.execSQL(query);
onCreate(db);
}
}
DBManager.java
public class DBManager {
private static final String TAG = "DBManager";
private DBHelper dbHelper;
private Context context;
private SQLiteDatabase database;
public DBManager(Context c) {
context = c;
}
public DBManager open() throws SQLException {
dbHelper = new TransactionDBHelper(context);
database = dbHelper.getWritableDatabase();
return this;
}
public void close() {
dbHelper.close();
}
public void insert(TxnSummary txnSummary) {
ContentValues contentValue = new ContentValues();
contentValue.put(DBHelper.param1, "1234");
contentValue.put(DBHelper.param2, "test");
contentValue.put(DBHelper.param3, "testdata1");
contentValue.put(DBHelper.param4,"testdata2");
long count = database.insert(DBHelper.TABLE_NAME, null, contentValue);
Log.d(TAG,"Data is inserted in database count is : "+count);
}
public Cursor fetch() {
String query = "SELECT "+DBHelper.param1+","
+DBHelper.param2+","
+DBHelper.param3+","
+DBHelper.param4
+" FROM "+DBHelper.TABLE_NAME;
Cursor cursor = database.rawQuery(query,null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
}
}
SummaryFragment.java
public class SumarryFragment extends Fragment {
final String[] from = new String[] {DBHelper.param1, Helper.param2,
DBHelper.param3,DBHelper.param4};
final int[] to = new int[] { R.id.textViewtxnList1,
R.id.textViewtxnList2,
R.id.textViewtxnList3,
R.id.textViewtxnList4 };
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_txnsumarry, container, false);
context = getContext();
ListView txnListView = (ListView) view.findViewById(R.id.summarylistview);
DBManager dbManager = new DBManager(getActivity());
dbManager.open();
cursor = dbManager.fetch();
simpleCursorAdapter = new SimpleCursorAdapter(getActivity(),R.layout.fragment_summary,cursor,from,to,0);
simpleCursorAdapter.notifyDataSetChanged();
txnListView.setAdapter(simpleCursorAdapter);
return view;
}
}
我的观点是
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:orientation="horizontal"
android:layout_height="wrap_content">
<TextView
android:id="@+id/textViewList1"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:layout_marginLeft="2dp"
android:text="PARAM1" />
<TextView
android:id="@+id/textViewList2"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:text="PARAM2" />
<TextView
android:id="@+id/textViewList3"
android:layout_width="75dp"
android:layout_height="wrap_content"
android:text="PARAM3" />
<TextView
android:id="@+id/textViewList4"
android:layout_width="80dp"
android:layout_height="wrap_content"
android:text="PARAM4" />
</LinearLayout>
</LinearLayout>
答案 0 :(得分：0)
您必须在2中更改数据库版本，或者只是删除并创建新数据库。
答案 1 :(得分：0)
首先，您必须确保数据库实际包含该列（增加数据库版本）。
然后，您还必须确保查询实际返回您要读取的所有列：
String query = "SELECT "+DBHelper.param1+","
+DBHelper.param2+","
+DBHelper.param3+","
+DBHelper.param4
+" FROM "+DBHelper.TABLE_NAME;