我不确定我学习如何使用 SQLite 数据库的简单程序发生了什么。我的程序基于在这个站点上找到的程序。我决定消除使用变量的问题,并将所有内容都写入我的创建表字符串。我也尝试过使用适当的 KEY_CONTENT 等但无济于事。希望这是足够的代码让您了解问题所在。另外,是否有任何我可以编写的代码(日志或 Toast 输出)有助于找出问题所在?
public class SQLiteAdapter {
public static final String DB_NAME = "My_Database";
public static final String DB_TABLE = "My_Table";
public static final int DB_VERSION = 1;
public static final String KEY_CONTENT = "My_Content";
String SCRIPT_CREATE_DATABASE = "CREATE TABLE My_Table (_id INTEGER PRIMARY KEY AUTOINCREMENT, My_Content TEXT);";
private SQLiteHelper sqLiteHelper;
private SQLiteDatabase sqLiteDatabase;
private Context context;
public SQLiteAdapter(Context c){
context = c;
}
public SQLiteAdapter openToRead() throws android.database.SQLException {
sqLiteHelper = new SQLiteHelper(context, DB_NAME, null, DB_VERSION);
sqLiteDatabase = sqLiteHelper.getReadableDatabase();
return this;
}
public SQLiteAdapter openToWrite() throws android.database.SQLException {
sqLiteHelper = new SQLiteHelper(context, DB_NAME, null, DB_VERSION);
sqLiteDatabase = sqLiteHelper.getWritableDatabase();
return this;
}
public void close(){
sqLiteHelper.close();
}
public long insert(String content){
ContentValues contentValues = new ContentValues();
contentValues.put("My_Content", content);
return sqLiteDatabase.insert("My_Table", null, contentValues);
}
public int deleteAll(){
return sqLiteDatabase.delete(DB_TABLE, null, null);
}
public String queueAll(){
String[] columns = new String[]{KEY_CONTENT};
Cursor cursor = sqLiteDatabase.query(DB_TABLE, columns,
null, null, null, null, null);
String result = "";
int index_CONTENT = cursor.getColumnIndex(KEY_CONTENT);
for(cursor.moveToFirst(); !(cursor.isAfterLast()); cursor.moveToNext()){
result = result + cursor.getString(index_CONTENT) + "\n";
}
return result;
}
public class SQLiteHelper extends SQLiteOpenHelper {
public SQLiteHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(SCRIPT_CREATE_DATABASE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
}
我的主要活动开始像这样处理 SQLite DB:
mySQLiteAdapter = new SQLiteAdapter(this);
mySQLiteAdapter.openToWrite();
mySQLiteAdapter.insert("First try");
这是Logcat:
04-25 14:19:37.404: E/Database(217): Error inserting My_Content=First try
04-25 14:19:37.404: E/Database(217): android.database.sqlite.SQLiteException: no such table: My_Table: , while compiling: INSERT INTO My_Table(My_Content) VALUES(?);
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteProgram.native_compile(Native Method)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteProgram.compile(SQLiteProgram.java:110)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:59)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:41)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteDatabase.compileStatement(SQLiteDatabase.java:1027)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1413)
04-25 14:19:37.404: E/Database(217): at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1286)
04-25 14:19:37.404: E/Database(217): at com.willmer.trialsqlite.SQLiteAdapter.insert(SQLiteAdapter.java:53)
04-25 14:19:37.404: E/Database(217): at com.willmer.trialsqlite.TrialSQLiteActivity.onCreate(TrialSQLiteActivity.java:25)
04-25 14:19:37.404: E/Database(217): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-25 14:19:37.404: E/Database(217): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
04-25 14:19:37.404: E/Database(217): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
04-25 14:19:37.404: E/Database(217): at android.app.ActivityThread.access$2200(ActivityThread.java:119)
04-25 14:19:37.404: E/Database(217): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
04-25 14:19:37.404: E/Database(217): at android.os.Handler.dispatchMessage(Handler.java:99)
04-25 14:19:37.404: E/Database(217): at android.os.Looper.loop(Looper.java:123)
04-25 14:19:37.404: E/Database(217): at android.app.ActivityThread.main(ActivityThread.java:4363)
04-25 14:19:37.404: E/Database(217): at java.lang.reflect.Method.invokeNative(Native Method)
04-25 14:19:37.404: E/Database(217): at java.lang.reflect.Method.invoke(Method.java:521)
04-25 14:19:37.404: E/Database(217): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
04-25 14:19:37.404: E/Database(217): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
04-25 14:19:37.404: E/Database(217): at dalvik.system.NativeStart.main(Native Method)