我正在尝试制作一个带有SQLite数据库的Android应用，但当我尝试对表格进行查询时，“activities”会向我显示RuntimeException。我尝试了很多东西，我找到了许多解决方案，但都没有。
我已经从数据库浏览器为SQLite
引起：android.database.sqlite.SQLiteException：没有这样的表： 活动（代码1）：在编译时：从活动中选择*
我知道可能这个问题是重复的，但是在其他问题中评论的所有内容对我都不起作用!!!!!
以下是扩展SQLiteOpenHelper
public class CuencasDbHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 2;
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.example.kazuelonga.vivecuencabbdd/databases";
private static String DB_NAME = "vivecuenca_database3.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
public CuencasDbHelper(Context context) {
super(context, DB_NAME, null, DATABASE_VERSION);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException {
boolean dbExist = false;
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
this.close();
try {
copyDataBase();
Log.v("copyDataBase---", "Successfully");
} catch (IOException e) {
e.toString();
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
File databasePath = myContext.getDatabasePath(DB_NAME);
Log.v("SQLite Error", "database does't exist yet.");
return databasePath.exists();
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[4096];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
//Open the database
String myPath = DB_PATH + DB_NAME;
this.getWritableDatabase();
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + CuencaEntry.TABLE_NAME);
if(newVersion>oldVersion)
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
当我尝试使用查询时会发生错误。
public Cursor getStringDB(){
return getReadableDatabase()
.query(
CuencaEntry.TABLE_NAME,
null,
CuencaEntry.TIPO + " LIKE 'pub'",
null,
null,
null,
null,
null);
}
这是我在MainActivity中调用Helper时的代码
CuencasDbHelper myDbHelper = new CuencasDbHelper(this);
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
myDbHelper.openDataBase();
}catch(SQLException sqle){
throw sqle;
}