Hexa's Blog

Making new table on an exist database - Android

19/07/2014 Android

When working on my assignment in course named Mobile Application. I had a problem that my program has two tables, both of them belong to a single database.

In my program, I used SQLiteHelper, the program has two diffirential classes which handle database working process.

1. GroupDaoImpl

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public class TaskGroupImpl extends SQLiteOpenHelper implements TaskGroupDao{
    private static TaskGroupImpl instance = null;
    private Context context;
    private ArrayList<TaskGroup> groups;
    //DATABASE information
    private static final int DB_VERSION = 1;
    private static final String DB_NAME = "TaskManager";
    private static final String TABLE_NAME = "task_group";

    //TABLE information
    private static final String GROUP_ID = "ID";
    private static final String GROUP_NAME = "NAME";


    private TaskGroupImpl(Context context){
       super(context, DB_NAME, null, DB_VERSION);
       this.context = context;
    }
    public static TaskGroupImpl getInstance(Context context){
        Log.v("TaskGroupImpl: ", "getInstance() active");
        if (instance == null){
            instance = new TaskGroupImpl(context);
            instance.groups = new ArrayList<TaskGroup>();
        }
        return instance;
    }
    public ArrayList<TaskGroup> getAllGroups(){
        return groups;
    }
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        String create_db = "CREATE TABLE " + TABLE_NAME+ "("
                + GROUP_ID + " INTEGER PRIMARY KEY, "
                + GROUP_NAME + " TEXT"  + ")";
        sqLiteDatabase.execSQL(create_db);
        Log.v("TaskGroup: ", "Did make TaskGroup table");
    }
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i2) {
        sqLiteDatabase.execSQL("DROP TABLE IF EXIST " + TABLE_NAME);
        onCreate(sqLiteDatabase);
    }

    @Override
    public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //super.onDowngrade(db, oldVersion, newVersion);
    }

    @Override
    public int createGroup(TaskGroup taskGroup) {
        try {
            int maxID;
            if(groups.isEmpty() == true){
                maxID = 0;
                taskGroup.setID(maxID);
            } else {
                maxID = groups.get(groups.size() - 1).getID() + 1;
                taskGroup.setID(maxID);
            }
            groups.add(taskGroup);
            SQLiteDatabase db = this.getWritableDatabase();
            ContentValues values= new ContentValues();
            values.put(GROUP_ID,taskGroup.getID());
            values.put(GROUP_NAME, taskGroup.getName());
            db.insert(TABLE_NAME, null, values);
            db.close();
            return 1;
        } catch (Exception ex){
            Log.v("TaskGroupImpl: ", "cannot create new group" );
            return 0;
        }
    }
    @Override
    public TaskGroup getTaskGroupById(int id) {
        for(int i = 0; i < groups.size(); i++){
            if (groups.get(id).getID() == id){
                return groups.get(id);
            }
        }
        return null;
    }
    @Override
    public int updateTaskGroup(TaskGroup taskGroup) {
        return 0;
    }
    @Override
    public int deleteTaskGroup(TaskGroup taskGroup) {
        try{

            SQLiteDatabase db = this.getWritableDatabase();
            db.delete(TABLE_NAME, GROUP_ID + " = ?", new String[] {String.valueOf(taskGroup.getID())});
            groups.remove(taskGroup);
            return 1;
        }
       catch (Exception ex){
           return 0;
       }
    }
    public void init(){
        groups.removeAll(groups);
        String query = "SELECT * FROM " + TABLE_NAME;
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor  = db.rawQuery(query, null);

        if (cursor.moveToFirst()){
            do{
                TaskGroup group = new TaskGroup();
                group.setID(Integer.parseInt(cursor.getString(0)));
                group.setName(cursor.getString(1));
                groups.add(group);
            } while (cursor.moveToNext());
        }
    }
}

2. TaskDaoImpl

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public class TaskDaoImpl extends SQLiteOpenHelper implements TaskDao  {
    //singleton
    private static TaskDaoImpl instance = null;
    private Context context;

    private ArrayList<Task> tasks;
    private static final int DATABASE_VERSION = 1;
    private static final  String DATABASE_NAME = "TaskManager";
    private static final String TABLE_TASK = "task";


    //TABLE INFORMATION
    private static final String taskId = "ID";
    private static final String taskTitle= "TITLE";
    private static final String taskNote= "NOTE";
    private static final String taskDueDate = "DATE";
    private static final String taskPriorityLevel = "PRIORITY";
    private static final String taskCollaborators = "COLLABORATOR";
    private static final String taskStatus = "STATUS";
    private static final String taskGroupId = "GROUPID";
    private SQLiteDatabase mydatabase;



    private TaskDaoImpl(Context context){
        super(context,DATABASE_NAME, null,DATABASE_VERSION);
        this.context = context;
    }

    public static TaskDaoImpl getInstance(Context ctx){
        if(instance == null){
            instance = new TaskDaoImpl(ctx);
            instance.tasks = new ArrayList<Task>();
            instance.createTableIfNotExist();
            Log.v("TaskDaoImpl: ", "getInstance() active");

        }
        return instance;
    }
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        String create_db = "CREATE TABLE " + TABLE_TASK + "(" +
                taskId + " INTEGER PRIMARY KEY, "+
                taskTitle +" TEXT, "+
                taskNote + " TEXT, "+
                taskDueDate +" INTEGER, "+
                taskPriorityLevel +" INTEGER, "+
                taskCollaborators + " TEXT, "+
                taskStatus + " INTEGER, "+
                taskGroupId + " INTEGER"
                + ")";
        sqLiteDatabase.execSQL(create_db);
        Log.v("TaskDaoImpl", "Did create table " +TABLE_TASK);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i2) {
        onCreate(sqLiteDatabase);
    }

    public void createTableIfNotExist(){
        mydatabase = this.getWritableDatabase();
        String create_db = "CREATE TABLE IF NOT EXISTS " + TABLE_TASK + "(" +
                taskId + " INTEGER PRIMARY KEY, "+
                taskTitle +" TEXT, "+
                taskNote + " TEXT, "+
                taskDueDate +" INTEGER, "+
                taskPriorityLevel +" INTEGER, "+
                taskCollaborators + " TEXT, "+
                taskStatus + " INTEGER, "+
                taskGroupId + " INTEGER"
                + ")";
        mydatabase.execSQL(create_db);
    }
    @Override
    public ArrayList<Task> getAllTasks() {
        return tasks;
    }

    @Override
    public int createTask(Task task) {
        int maxID;
        if(tasks.isEmpty() == true){
            maxID = 0;
        } else {
            int id = tasks.get(tasks.size()-1).getId();
            maxID = id+1;
        }
        task.setId(maxID);
        tasks.add(task);
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(taskId, task.getId());
        values.put(taskTitle, task.getTitle());
        values.put(taskNote, task.getNote());
        values.put(taskDueDate, task.getDueDate().getTime()/1000);
        values.put(taskPriorityLevel, task.getPriorityLevel());

        //collaborator from arraylist to String
        StringBuilder stringB = new StringBuilder();
        for (int i = 0; i < task.getCollaborator().size(); i++){
            stringB.append(task.getCollaborator().get(i));
            if (i < task.getCollaborator().size() -1){
                stringB.append(",");
            }
        }
        values.put(taskCollaborators, stringB.toString());
        values.put(taskStatus, task.isCompletionStatus());
        values.put(taskGroupId,task.getGroupID());

        db.insert(TABLE_TASK,null,values);
        db.close();
        return 1;
    }
    @Override
    public Task getTaskByID(int id) {
        for(int i = 0;i < tasks.size(); i++){
            if(tasks.get(i).getId() == id ){
                return tasks.get(i);
            }
        }
        return null;
    }
    public ArrayList<Task> getTaskByGroupID(int id){
        ArrayList<Task> filteredList = new ArrayList<Task>();
        for (int i = 0; i <tasks.size(); i++){
            if(tasks.get(i).getGroupID() == id){
                filteredList.add(tasks.get(i));
            }
        }
        return filteredList;
    }
    public void deleteTaskByGroupID(int groupID){
        for(int x = 0; x < tasks.size();x++){
            if(tasks.get(x).getGroupID() == groupID){
                deleteTask(tasks.get(x));
                x--;
            }
        }
    }
    @Override
    public int updateTask(Task task) {
        for (int i = 0; i< tasks.size();i++){
            if(tasks.get(i).getId() == task.getId()){
                tasks.get(i).setCollaborator(task.getCollaborator());
                tasks.get(i).setCompletionStatus(task.isCompletionStatus());
                tasks.get(i).setDueDate(task.getDueDate());
                tasks.get(i).setPriorityLevel(task.getPriorityLevel());
                tasks.get(i).setTitle(task.getTitle());
                tasks.get(i).setNote(task.getNote());
                return 1;
            }
        }
        return 0;
    }
    @Override
    public int deleteTask(Task task) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.beginTransaction();
        db.delete(TABLE_TASK, taskId + " = ?", new String[] {String.valueOf(task.getId())});
        db.setTransactionSuccessful();
        db.endTransaction();
        Log.v("TaskDaoImpl: ", task.getId() + "-"+task.getTitle());
        tasks.remove(task);
        db.close();

        return 0;
    }

    public void init(){
        tasks.removeAll(tasks);
        Log.v("TaskDaoImpl: " , "init method");
        SQLiteDatabase db = this.getReadableDatabase();
        String query = "SELECT  * FROM " + TABLE_TASK;
        Cursor cursor = db.rawQuery(query, null);
        if(cursor.moveToFirst()){
            do{
                Task task = new Task();
                task.setId(Integer.parseInt(cursor.getString(0)));
                task.setTitle(cursor.getString(1));
                task.setNote(cursor.getString(2));
                Date datetime = new Date(Long.parseLong(cursor.getString(3)) * 1000);
                Log.v("datetime ", datetime.toString());
                task.setDueDate(datetime);

                task.setPriorityLevel(Integer.parseInt(cursor.getString(4)));
                //get collaborators
                String collaboratorsS = cursor.getString(5);
                ArrayList<String> colaList = new ArrayList<String>(Arrays.asList(collaboratorsS.split(",")));
                task.setCollaborator(colaList);
                //get status
                if(Integer.parseInt(cursor.getString(6)) == 0){
                    task.setCompletionStatus(false);
                } else {
                    task.setCompletionStatus(true);
                }
                //set group id
                task.setGroupID(Integer.parseInt(cursor.getString(7)));
                task.print();
                //add to array list - lists
                tasks.add(task);
            } while(cursor.moveToNext());
        }
    }
}

#ISSULE AND PROBLEM In general, in order to use SQLiteHelper to make new table and database. function named onCreate(SQLiteDatabase db) will be invoked to do that. In my program, TaskGroupImpl instance is initialized before TaskDaoImpl, bug happend here, when I make a new instance of TaskDaoImpl - ofcourse after TaskGroupImpl, table named task would not be created or function named onCreate(SQLiteDatabase db) is not invoked.

#Solution

I make an extra function to make new table manually. This function named createTableIfNotExist(), it belong to TaskDaoImpl class - because it has a new table which I want to make but not create automatically by SQLiteHelper.

When make call a instance of TaskDaoImpl, I also check to make a new table name task. If it is exist, make no new table, if not, make a new table.

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public void createTableIfNotExist(){
        mydatabase = this.getWritableDatabase();
        String create_db = "CREATE TABLE IF NOT EXISTS " + TABLE_TASK + "(" +
                taskId + " INTEGER PRIMARY KEY, "+
                taskTitle +" TEXT, "+
                taskNote + " TEXT, "+
                taskDueDate +" INTEGER, "+
                taskPriorityLevel +" INTEGER, "+
                taskCollaborators + " TEXT, "+
                taskStatus + " INTEGER, "+
                taskGroupId + " INTEGER"
                + ")";
        mydatabase.execSQL(create_db);
    }

In the contructor, I call this function to make a new table.

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ublic static TaskDaoImpl getInstance(Context ctx){
        if(instance == null){
            instance = new TaskDaoImpl(ctx);
            instance.tasks = new ArrayList<Task>();
            instance.createTableIfNotExist();
            Log.v("TaskDaoImpl: ", "getInstance() active");

        }
        return instance;
    }