这个问题很有名，但每个人都说要去看Notepad Tutorial。
这会有所帮助，但是当你遇到困难时，这并没有多大帮助。
所以我有这个我在Android上创建的数据库，我想在列表视图中显示它，我做了教程，但我仍然不明白为什么我不能让它在我的项目上工作，所以如果有人可以提供帮助，请展示自己！
这是我的代码
public class MyFridge extends ListActivity {
private DBAdapter db;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.notepad_list);
db = new DBAdapter(this);
db.open();
fillData();
}@Override
public boolean onCreateOptionsMenu (Menu menu)
{
super.onCreateOptionsMenu(menu);
CreateMenu(menu);
return true;
}
@Override
public boolean onOptionsItemSelected (MenuItem item)
{
switch(item.getItemId())
{
case 0:
Intent f = new Intent(MyFridge.this, Addform.class);
startActivity(f);
return true;
case 1:
Intent r = new Intent(MyFridge.this, MyRecipes.class);
startActivity(r);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void CreateMenu(Menu menu)
{
MenuItem mnu1 = menu.add(0, 0, 0, "Add ingredient");
{
mnu1.setAlphabeticShortcut('a');//Change the alphabetic shortcut associated with this item.
mnu1.setIcon(R.drawable.ic_launcher);
}
MenuItem mnu2 = menu.add(0, 1, 1, "Delete ingredient");
{
mnu2.setAlphabeticShortcut('b');//Change the alphabetic shortcut associated with this item.
mnu2.setIcon(R.drawable.ic_launcher);
}
}
private void fillData() {
// Get all of the notes from the database and create the item list
Cursor c = db.getAllCars();
startManagingCursor(c);
String[] from = new String[] { DBAdapter.KEY_TYPE };
int[] to = new int[] { R.id.text1 };
// Now create an array adapter and set it to display using our row
SimpleCursorAdapter notes =
new SimpleCursorAdapter(this, R.layout.notes_row, c, from, to);
setListAdapter(notes);
}
这是我的数据库：
public class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_TYPE = "type";
public static final String KEY_WEIGHT = "weight";
public static final String KEY_EXP = "expiration day";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "MyDB";
private static final String DATABASE_TABLE = "Fridge";
private static final int DATABASE_VERSION = 2;
private static final String DATABASE_CREATE =
"create table Fridge (_id integer primary key autoincrement, "
+ "type text not null, weight integer not null, exp integer not null);";
//CHECK (P_Id>0)
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
//It lets newly created objects understand what has been going on.
//Typically you call it to get information regarding another part of your program
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);//calls the context in the parent class
}
@Override
public void onCreate(SQLiteDatabase db)
{
try {
db.execSQL(DATABASE_CREATE);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) // this method is used if the OS or the version App is changed
{
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS cars");
onCreate(db);
}
}
//---opens the database---
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---insert a contact into the database---
public long insertCar(String type, int weight, int exp)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TYPE, type);
initialValues.put(KEY_WEIGHT, weight);
initialValues.put(KEY_EXP, exp);
return db.insert(DATABASE_TABLE, null, initialValues);
}
//---deletes a particular contact---
public boolean deleteCar(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
//---retrieves all the contacts---
public Cursor getAllCars()
{
return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TYPE,
KEY_WEIGHT, KEY_EXP}, null, null, null, null, null);
}
/*
* retrieves a particular car
*
*/
public Cursor getCar(String searchString) //throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_TYPE, KEY_WEIGHT,KEY_EXP},KEY_TYPE +"="+"'"+searchString+"'" +" OR "+ KEY_ROWID + "=" + "'"+searchString +"'"+" OR "+ KEY_EXP + "=" + "'"+searchString +"'"+" OR " + KEY_WEIGHT + "=" + "'" + searchString +"'", null,
null, null, null, null);
return mCursor;
}
//---updates a contact---
public boolean updateCar(long rowId, String type, int weight, int exp)
{
ContentValues args = new ContentValues();
args.put(KEY_TYPE, type);
args.put(KEY_WEIGHT, weight);
args.put(KEY_EXP, exp);
return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
Logcat信息。
04-09 18:14:47.128: D/TextLayoutCache(23297): Using debug level: 0 - Debug Enabled: 0
04-09 18:14:47.173: D/CLIPBOARD(23297): Hide Clipboard dialog at Starting input: finished by someone else... !
04-09 18:14:49.113: I/SqliteDatabaseCpp(23297): sqlite returned: error code = 1, msg = no such table: Fridge, db=xxx
04-09 18:14:49.113: D/AndroidRuntime(23297): Shutting down VM
04-09 18:14:49.118: W/dalvikvm(23297): threadid=1: thread exiting with uncaught exception (group=0x40c281f8)
04-09 18:14:49.123: E/AndroidRuntime(23297): FATAL EXCEPTION: main
04-09 18:14:49.123: E/AndroidRuntime(23297): java.lang.RuntimeException: Unable to start activity ComponentInfo{wijayaratnam.sutharsun.mobilefridge/wijayaratnam.sutharsun.mobilefridge.MyFridge}: android.database.sqlite.SQLiteException: no such table: Fridge: , while compiling: SELECT _id, type, weight, expiration day FROM Fridge
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1968)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1993)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread.access$600(ActivityThread.java:127)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1159)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.os.Handler.dispatchMessage(Handler.java:99)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.os.Looper.loop(Looper.java:137)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread.main(ActivityThread.java:4507)
04-09 18:14:49.123: E/AndroidRuntime(23297): at java.lang.reflect.Method.invokeNative(Native Method)
04-09 18:14:49.123: E/AndroidRuntime(23297): at java.lang.reflect.Method.invoke(Method.java:511)
04-09 18:14:49.123: E/AndroidRuntime(23297): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
04-09 18:14:49.123: E/AndroidRuntime(23297): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
04-09 18:14:49.123: E/AndroidRuntime(23297): at dalvik.system.NativeStart.main(Native Method)
04-09 18:14:49.123: E/AndroidRuntime(23297): Caused by: android.database.sqlite.SQLiteException: no such table: Fridge: , while compiling: SELECT _id, type, weight, expiration day FROM Fridge
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1690)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1575)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1531)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1611)
04-09 18:14:49.123: E/AndroidRuntime(23297): at wijayaratnam.sutharsun.mobilefridge.DBAdapter.getAllCars(DBAdapter.java:101)
04-09 18:14:49.123: E/AndroidRuntime(23297): at wijayaratnam.sutharsun.mobilefridge.MyFridge.fillData(MyFridge.java:146)
04-09 18:14:49.123: E/AndroidRuntime(23297): at wijayaratnam.sutharsun.mobilefridge.MyFridge.onCreate(MyFridge.java:29)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.Activity.performCreate(Activity.java:4465)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052)
04-09 18:14:49.123: E/AndroidRuntime(23297): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1932)
04-09 18:14:49.123: E/AndroidRuntime(23297): ... 11 more
答案 0 :(得分：0)
如果您的错误是sql“找不到列”，请将create table语句重写为：
private static final String DATABASE_CREATE =
"create table " + DATABASE_TABLE + " ("
+ KEY_ROWID + " integer primary key autoincrement, "
+ KEY_TYPE + " text not null, "
+ KEY_WEIGHT + " integer not null, "
+ KEY_EXP + " integer not null);";
您会注意到您定义了KEY_EXP = "expiration day"，但在您的create语句中，您手动调用了列exp;即未找到列。尽量使用您创建的变量来限制这些拼写错误。祝你好运！