как выбрать данные из базы данных с использованием базы данных SQLite в android?

Question

Я новичок в разработке Android и хотел бы выбрать данные и предварительно заполнить базу данных SQLite, используя файлы .sq3 из папки Assets. Но получая исключение на своем пути. Итак, что мне делать? вот мой код.

package com.wiztech.wahab; 

import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.database.sqlite.SQLiteOpenHelper; 

public class DataBaseManager extends SQLiteOpenHelper{ 

//The Android's default system path of your application database. 
    private static String DB_PATH = "/data/data/com.wiztech.wahab/databases/"; 


// private static String DB_NAME = "BlueConnect.sq3"; 
private static String DB_NAME = "database.sq3"; 



private SQLiteDatabase myDataBase; 
private SQLiteDatabase myData; 

private final Context myContext; 

public DataBaseManager(Context context) { 
    super(context, DB_NAME, null, 1); 
    this.myContext = context; 
} 

/** 
* Creates a empty database on the system and rewrites it with your own database. 
* */ 
public void createDataBase() throws IOException{ 

    boolean dbExist = checkDataBase(); 
    if(dbExist){ 
     //do nothing - database already exist 
    }else{ 
     CopyFiles(); 
    } 
} 


private void CopyFiles() 
{ 
    try 
    { 
     InputStream is = myContext.getAssets().open(DB_NAME); 
     File outfile = new File(DB_PATH,DB_NAME); 
     outfile.getParentFile().mkdirs(); 
     outfile.createNewFile(); 

     if (is == null) 
     throw new RuntimeException("stream is null"); 
     else 
     { 
     FileOutputStream out = new FileOutputStream(outfile);  
     // BufferedOutputStream out = new BufferedOutputStream(new  FileOutputStream(outfile)); 
      byte buf[] = new byte[128]; 
      do { 
      int numread = is.read(buf); 
       if (numread <= 0) 
        break; 
      out.write(buf, 0, numread); 
      } while (true); 

      is.close(); 
      out.close(); 
     } 
     //AssetFileDescriptor af = am.openFd("world_treasure_hunter_deluxe.apk"); 
    } 
    catch (IOException e) 
    { 
      throw new RuntimeException(e); 
    } 

}  

/** 
* 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(){ 

    SQLiteDatabase checkDB = null; 

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

    }catch(SQLiteException e){ 

    } 

    if(checkDB != null){ 
     checkDB.close(); 
    } 

    return checkDB != null ? true : false; 
} 

/** 
* 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. 
* */ 
@SuppressWarnings("unused") 
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[1024]; 
    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; 

    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) { 

} 


//---retrieve records--- 
public Cursor selectQuery(String query) throws SQLException 
{ 
    String myPath = DB_PATH + DB_NAME; 
    //myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 
    myData = SQLiteDatabase.openDatabase(myPath,null, SQLiteDatabase.CREATE_IF_NECESSARY); 
    Cursor mCursor =myData.rawQuery(query, null); 
    mCursor.moveToFirst();  
    myData.close(); 
    return mCursor; 
} 


////////// For Insert And Update Data //////// 
public void insert_update(String query) throws SQLException 
{ 
    String myPath = DB_PATH + DB_NAME; 
    myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 
    myData.execSQL(query); 
    myData.close();   
} 

public boolean UpdateVote_Individual(String rowid,String value,String count) { 
    String myPath = DB_PATH + DB_NAME; 
    myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 

     ContentValues args = new ContentValues(); 
     args.put("total_votes", count); 
     return myData.update("promotors", args, 
       "promoter_id='" + rowid+"'", null) > 0;   
    } 


} 






package com.wiztech.wahab; 

import android.app.Activity; 
import android.content.Intent; 
import android.database.Cursor; 
import android.graphics.Color; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 

public class Criteria_Activity extends Activity { 

DataBaseManager db; 
Cursor cur; 

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    System.out.println("reached inside Criteria_Activity"); 
    setContentView(R.layout.criteria); 

    db = new DataBaseManager(getBaseContext()); 
    cur = db.selectQuery("select * from client_table1;"); 

    if(cur.moveToFirst()) { 

     do { 

      String age = cur.getString(1); 
      String gender = cur.getString(2); 
      String prof = cur.getString(3); 
      String hobby = cur.getString(4); 
      String likes = cur.getString(5); 
      String dislikes = cur.getString(6); 

      TextView ag = (TextView) findViewById(R.id.age_value); 
      if(age.length()==0||age==""){ 
       age="Not Saved"; 
       ag.setTextSize(16); 
       ag.setTextColor(Color.GRAY); 
      } 
      ag.setText(age); 

      TextView gend = (TextView) findViewById(R.id.gender_value); 
      if(gender.length()==0||gender==""){ 
       gender="Not Saved"; 
       gend.setTextSize(16); 
       gend.setTextColor(Color.GRAY); 
      } 
      gend.setText(gender); 

      TextView pr = (TextView) findViewById(R.id.prof_value); 
      if(prof.length()==0||prof==""){ 
       prof="Not Saved"; 
       pr.setTextSize(16); 
       pr.setTextColor(Color.GRAY); 
      } 
      pr.setText(prof); 

      TextView hobbie = (TextView) findViewById(R.id.hobby_value); 
      if(hobby.length()==0||hobby==""){ 
       hobby="Not Saved"; 
       hobbie.setTextSize(16); 
       hobbie.setTextColor(Color.GRAY); 
      } 
      hobbie.setText(hobby); 

      TextView lykes = (TextView) findViewById(R.id.likes_value); 
      if(likes.length()==0||likes==""){ 
       likes="Not Saved"; 
       lykes.setTextSize(16); 
       lykes.setTextColor(Color.GRAY); 
      } 
      lykes.setText(likes); 

      TextView dislykes = (TextView) findViewById(R.id.dislikes_value); 
      if(dislikes.length()==0|| dislikes==""){ 
       dislikes="Not Saved"; 
       dislykes.setTextSize(16); 
       dislykes.setTextColor(Color.GRAY); 
      } 
      dislykes.setText(dislikes); 

     }while(cur.moveToNext()); 
     cur.close(); 
    }//end if(cur.moveToFirst.......... 

    Button criteria_edit_btn = (Button) findViewById(R.id.cr_edit_btn); 

    criteria_edit_btn.setOnClickListener(new OnClickListener(){ 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      Intent update_criteria_intent = new Intent(getParent(), Edit_Criteria_Activity.class); 
      TabGroupActivity parentActivity = (TabGroupActivity)getParent(); 
      parentActivity.startChildActivity("Edit_Criteria_Activity", update_criteria_intent); 
     }   
    }); 

}// end onCreate 

}//end this.Activity 

Answer 1

Ну, просто прочитайте, что находится в журнале. Вы делаете выбор на client_table1, но таблица не существует. Сначала вам нужно создать таблицу.

Пожалуйста, прочитайте в этом руководстве о том, как использовать SQLite на Android с помощью класса SQLiteOpenHelper:

http://www.vogella.de/articles/AndroidSQLite/article.html