为什么我收到错误“无法打开数据库”在Android？ [英] Why I Get error "Could Not Open Database" In Android?

问题描述

我搜索了我的问题，但没有解决方案有效!!

我有这样的课程：

I have searched allot for my problems but none of the solutions work!!
I have a class like this:

public class database extends SQLiteOpenHelper {

    private static String DB_PATH = "/data/data/com.example.MEN/databases/";

    private static String DB_NAME = "men";

    private SQLiteDatabase myDataBase;

    private final Context myContext;

    public database(Context context) {

        super(context, DB_NAME, null, 1);
        this.myContext = context;
    }

    public void createDataBase() throws IOException {

        boolean dbExist = checkDataBase();

        if(dbExist){
            //do nothing - database already exist
        }else{

            this.getReadableDatabase();

            try {

                copyDataBase();

            } catch (IOException e) {

                throw new Error("Error copying database");

            }
        }

    }
    
    private boolean checkDataBase(){

        SQLiteDatabase checkDB = null;

        try{
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

        }catch(SQLiteException e){

            //database does't exist yet.

        }

        if(checkDB != null){

            checkDB.close();

        }

        return checkDB != null ? true : false;
    }


    private void copyDataBase() throws IOException{

        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[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer, 0, length);
        }

        //Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    public String openDataBase() throws SQLException {

        //Open the database
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
        Cursor c=myDataBase.rawQuery("select Mistake from info",null);
        String s=c.getString(0);
    return s;
    }
    @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) {
    }
}

我在另一个类中使用它代码如下：

and i use it in another class by code like this:

database db;
        db = new database(this);

        try {

            db.createDataBase();

        } catch (IOException ioe) {

            throw new Error("Unable to create database");

        }

        try {
            String t;
            t=db.openDataBase();
            TextView tv= (TextView) findViewById(R.id.textView);
            tv.setText(t);
        }catch(SQLException sqle){

            try {
                throw sqle;
            } catch (SQLException e) {
                e.printStackTrace();
            }

        }

    }
}

但我每次都会收到错误我跑了!!!!

任何人都可以帮助我？

but i get that error every time i run it!!!!
anybody can help me??

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