SQLiteAssetHelper和getWritableDatabase

Question

I'm having have some trouble with my Database activity. I am unable to write to the database and view the database using the following code.

my Database activity:

package com.jacob.eindproject;

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.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;

import java.sql.*;

import com.readystatesoftware.sqliteasset.SQLiteAssetHelper;

public class Database extends SQLiteAssetHelper {

    public static final String KEY_PRODUCT = "Product";
    public static final String KEY_EENHEID = "Eenheid";
    public static final String KEY_KCAL = "Kcal";

    private static final String DATABASE_NAME = "Voedsel";
    private static final String DATABASE_TABLE = "Voeding";
    private static final int DATABASE_VERSION = 1;

    private DbHelper ourHelper;
    private final Context ourContext;
    private SQLiteDatabase ourDatabase;

    private static class DbHelper extends SQLiteAssetHelper{

        public DbHelper(Context context) {
            super(context, DATABASE_NAME, context.getExternalFilesDir(null).getAbsolutePath(), null, DATABASE_VERSION);
            // TODO Auto-generated constructor stub
        }

    }

        @Override
        public void onUpgrade(SQLiteDatabase Voedsel, int oldVersion, int newVersion) {
            Voedsel.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
            onCreate(Voedsel);
        }

        public void close(Database database) {
            // TODO Auto-generated method stub

        }




    public Database(Context c){
        ourContext = c;
    }

    public Database open() throws SQLException{
        ourHelper = new DbHelper(ourContext);
        ourDatabase = ourHelper.getWritableDatabase();
        return this;        
    }

    public void close() {

    ourHelper.close();
}



    public long createEntry(String product, String kcal, String eenheid) {
        ContentValues cv = new ContentValues();
        cv.put(KEY_PRODUCT, product);
        cv.put(KEY_EENHEID, eenheid);
        cv.put(KEY_KCAL, kcal);
        return ourDatabase.insert(DATABASE_TABLE, null, cv);

    }

    public String getData() {
        // TODO Auto-generated method stub
        String[] columns = new String[]{ KEY_PRODUCT, KEY_EENHEID, KEY_KCAL};
        Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
        String result = "";

        int iRow = c.getColumnIndex(KEY_PRODUCT);
        int iName = c.getColumnIndex(KEY_EENHEID);
        int iHotness = c.getColumnIndex(KEY_KCAL);

        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
            result = result + c.getString(iRow) + " " + c.getString(iName) + " " + c.getString(iHotness) + "\n";


        }

        return result;
    }
}

My SQLView activity:

package com.jacob.eindproject;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class SQLView extends Activity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sqlview);
        TextView tv = (TextView) findViewById(R.id.tvSQLinfo);
        Database info = new Database(this);
        info.open();
        String data = info.getData();
        info.close();
        tv.setText(data);





    }

}

SQLite activity:

package com.jacob.eindproject;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.app.Activity;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.view.View.OnClickListener;


public class SQLite extends Activity implements View.OnClickListener {

    Button sqlUpdate, sqlView;
    EditText sqlVoeding, sqlKcal, sqlEenheid;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sqllite);
        sqlUpdate = (Button) findViewById(R.id.bSQLUpdate);
        sqlVoeding = (EditText) findViewById(R.id.etSQLVoeding);
        sqlEenheid = (EditText) findViewById(R.id.etSQLEenheid);
        sqlKcal = (EditText) findViewById(R.id.etSQLKcal);

        sqlView = (Button) findViewById(R.id.bSQLopenView);
        sqlView.setOnClickListener((android.view.View.OnClickListener) this);
        sqlUpdate.setOnClickListener((android.view.View.OnClickListener) this);
    }

    public void onClick(View arg0) {
        switch (arg0.getId()) {
        case R.id.bSQLUpdate:


            boolean didItWork = true;
            try{            
            String voeding = sqlVoeding.getText().toString();
            String Kcal = sqlKcal.getText().toString();
            String eenheid = sqlEenheid.getText().toString();

            Database entry = new Database(SQLite.this);
            entry.open();
            entry.createEntry(voeding, Kcal, eenheid);
            entry.close();

            }catch (Exception e ){
                didItWork = false;

            }finally{
                if (didItWork){
                    Dialog d = new Dialog(this);
                    d.setTitle("Heak Yeay");
                    TextView tv = new TextView(this);
                    tv.setText("Succes");
                    d.setContentView(tv);
                    d.show();
            }
        }

            break;
        case R.id.bSQLopenView:
            Intent i = new Intent(this, SQLView.class);
            startActivity(i);


        }
        }

    public void onClick(DialogInterface arg0, int arg1) {
        // TODO Auto-generated method stub

    }

    }

I am having my database file(Voedsel.rar), in assets/databases/Voedsel.rar .

Answer 1

To write to your database, try a method like this:

public void insertVoeding(String product, String eenheid, String kcal) {
    ourDatabase.execSQL("INSERT INTO Voeding (Product, Eenheid, Kcal) VALUES (?, ?, ?)",
              new String[] {product, eenheid, kcal});
}

The question marks are replaced by the values in the string array. Your column names cannot be inserted using the string array, because the execSQL method puts quotation marks around these values. The query will fail if you try.

There are two ways to read from a database (may even be two ways to write to it, too). I personally prefer using raw queries, like this one to get the entire database:

public Cursor getEntireDB() {
    return ourDatabase.rawQuery("SELECT * FROM Voeding");
}

You can then use the cursor in a CursorAdapter to create a list.