Use sqlite to as a database log in android

Log2Sqlite.java

package com.example.alessandro.sqlitetest;

import java.util.LinkedList;
import java.util.List;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class Log2Sqlite extends SQLiteOpenHelper {
    // Database Version
    private static final int DATABASE_VERSION = 1;
    // Database Name
    private static final String DATABASE_NAME = "LogDB";

    public Log2Sqlite(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    //------------- TODO
    //-- 1. synchronized for add/delete
    //-- 2. SQLiteDatabase object singleton una tantum (concurrency managed in 1.)
    //-- 3. onclose/ondestroy/etc override for closing db at app exit

    @Override
    public void onCreate(SQLiteDatabase db) {
        // SQL statement to create log table
        String CREATE_LOGS_TABLE = "CREATE TABLE logs ( " +
        "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
        "content TEXT)";

        // create log table
        db.execSQL(CREATE_LOGS_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older logs table if existed
        db.execSQL("DROP TABLE IF EXISTS logs");
        // create fresh logs table
        this.onCreate(db);
    }

    /**
     * CRUD operations (create "add", read "get", update, delete) log + get all log + delete all logs
     */

    // Logs table name
    private static final String TABLE_LOGS = "log";
    // Logs Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_CREATED = "created";
    private static final String KEY_CONTENT = "content";

    private static final String[] COLUMNS = {KEY_ID, KEY_CREATED, KEY_CONTENT};

    public void addLog(LogModel logModel) {
        Log.d("addLog", logModel.toString());
        // 1. get reference to writable DB
        SQLiteDatabase db = this.getWritableDatabase();
        // 2. create ContentValues to add key "column"/value
        ContentValues values = new ContentValues();
        values.put(KEY_CREATED, logModel.getCreated());
        values.put(KEY_CONTENT, logModel.getContent());
        // 3. insert
        db.insert(TABLE_LOGS, // table
            null, //nullColumnHack
            values); // key/value -> keys = column names/ values = column values
        // 4. close
        db.close();
    }

    public LogModel getLogModel(int id) {
        // 1. get reference to readable DB
        SQLiteDatabase db = this.getReadableDatabase();
        // 2. build query
        Cursor cursor = db.query(TABLE_LOGS, // a. table
                COLUMNS, // b. column names
                " id = ?", // c. selections
                new String[]{String.valueOf(id)}, // d. selections args
                null, // e. group by
                null, // f. having
                null, // g. order by
                null); // h. limit
        // 3. if we got results get the first one
        if (cursor != null) {
            cursor.moveToFirst();
        }
        // 4. build log object
        LogModel logModel = new LogModel();
        logModel.setId(Integer.parseInt(cursor.getString(0)));
        logModel.setCreated(Integer.parseInt(cursor.getString(1)));
        logModel.setContent(cursor.getString(2));

        Log.d("getLog(" + id + ")", logModel.toString());

        // 5. return log
        return logModel;
    }

    // Get All Logs
    public List<LogModel> getAllLogs() {
        List<LogModel> logs = new LinkedList<LogModel>();

        //1. build the query
        String query = "SELECT  * FROM " + TABLE_LOGS;

        //2. get reference to writable DB
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(query, null);

        //3. go over each row, build log and add it to list
        LogModel logModel = null;
        if (cursor.moveToFirst()) {
            do {
                logModel = new LogModel();
                logModel.setId(Integer.parseInt(cursor.getString(0)));
                logModel.setCreated(Integer.parseInt(cursor.getString(1)));
                logModel.setContent(cursor.getString(2));

                // Add log to logs
                logs.add(logModel);
            } while (cursor.moveToNext());
        }
        Log.d("getAllLogs()", logModel.toString());

        // return logs
        return logs;
    }

    // Deleting single log
    public void deleteLog(LogModel logModel) {
        // 1. get reference to writable DB
        SQLiteDatabase db = this.getWritableDatabase();
        // 2. delete
        db.delete(TABLE_LOGS,
            KEY_ID + " = ?",
            new String[]{String.valueOf(logModel.getId())});
        // 3. close
        db.close();
        Log.d("deleteLog", logModel.toString());
    }
}