Building a TODO List app in Android using SQLite

Storing data locally in Android is very easy. Here are few ways we can do it:

1. Using SharedPreferences
2. Using Files
3. Using SQL databases.

This tutorial will tell you how to save data using SQL databases. For this we are taking a very simple application which stores a very simple list of tasks with their boolean status: done or not done.

The Database

The database contains only one table called "task" which has the following columns:

1. Id
2. Task
3. Status

This tutorial will show us how to save data in a SQL database. For this we are would build a very simple application which stores a list of tasks with their boolean status(whether done or not done).

Creating the project

Create a project in eclipse with a activity called ViewTaskActivity like the following:

Here is the manifest


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.tasker"
   android:versionCode="1"
   android:versionName="1.0" >
    <uses-sdk
       android:minSdkVersion="17"
       android:targetSdkVersion="17" />
    <application
       android:allowBackup="true"
       android:icon="@drawable/ic_launcher"
       android:label="@string/app_name"
       android:theme="@style/AppTheme" >
        <activity
           android:name="com.example.tasker.ViewTask"
           android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>
 

Setting up the database helper

Now in the app you need to create a simple java class to represent the task. This will help us when we set up operations for the database.

In Android we need to set up a database helper which will help in performing operations on the database. For now I am only going to define three database operations: Create, Read and Update.

In order to create a Database helper, we create a class that would extend SQLiteOpenHelper. And you also need to put in two methods: on Create() and onUpgrade().

onCreate() is called only one time when the database is accessed the first time. It will contain all the table create statements. And onUpgrade() is called when database is modifed in any way. So here is the helper class initially.

Adding Create Operation

Now as I said we need to add three operations on this database. Lets start with Create.


public void addTask(Task task) {
    SQLiteDatabase db = this.getWritableDatabase();
     
    ContentValues values = new ContentValues();
    values.put(KEY_TASKNAME, task.getTaskName()); // task name
     // status of task- can be 0 for not done and 1 for done
    values.put(KEY_STATUS, task.getStatus());
     
    // Inserting Row
    db.insert(TABLE_TASKS, null, values);
    db.close(); // Closing database connection
}
 

Adding a Read Operation

We will read from database and store all values in an Array list.


public List<Task> getAllTasks() {
    List<Task> taskList = new ArrayList<Task>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_TASKS;
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);
    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Task task = new Task();
            task.setId(cursor.getInt(0));
            task.setTaskName(cursor.getString(1));
            task.setStatus(cursor.getInt(2));
            // Adding contact to list
            taskList.add(task);
        } while (cursor.moveToNext());
    }
    // return task list
    return taskList;
}
 

The update operation

In this app I only need to update the status of the task. Status is 0 if task is not done and 1 if done.


public void updateTask(Task task) {
    // updating row
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(KEY_TASKNAME, task.getTaskName());
    values.put(KEY_STATUS, task.getStatus());
    db.update(TABLE_TASKS, values, KEY_ID + " = ?",
                  new String[]{String.valueOf(task.getId())});
}
 

The View

I will try to include all options in one view so that the App has two seections in one screen. On the top is a EditText and an "Add" button to add tasks. And below that are the tasks in a ListView. The xml file for this view is as follows:

This list view is going to have a different view inside it. A checkbox to show status of the task as well as the description of the task. Pretty simple and easy right??? Lets see how that works out.

Create a new xml file in your layout folder called list_inner_view.xml and add the following controls in it:


<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent" >
    <CheckBox
       android:id="@+id/checkBox1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_alignParentLeft="true"
       android:focusable="false"
       android:focusableInTouchMode="false"
       android:text="CheckBox" />

</RelativeLayout>
 

For now as there are no tasks added our app looks like this

Adding the logic

Now to populate my list view I will need a custom data adapter so inside my activity class I am going to create a private class extending an ArrayAdapter. The class is inside the activity we created earlier.


private class MyAdapter extends ArrayAdapter<Task>
{
    Context context;
    List<Task> taskList=new ArrayList<Task>();
    int layoutResourceId;
    public MyAdapter(Context context, int layoutResourceId,
            List<Task> objects) {
        super(context, layoutResourceId, objects);
        this.layoutResourceId = layoutResourceId;
        this.taskList=objects;
        this.context=context;
    }
    /**This method will DEFINe what the view inside the list view will finally look like
     * Here we are going to code that the checkbox state is the status of task and
     * check box text is the task name
     */
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View rowView = inflater.inflate(R.layout.list_inner_view, parent, false);
        CheckBox chk=(CheckBox)rowView.findViewById(R.id.chkStatus);
        Task current=taskList.get(position);
        chk.setText(current.getTaskName());
        chk.setChecked(current.getStatus()==1?true:false);
 
        return rowView;
    }

}
 

Now you on start up of the app we need to add a few lines in the Activity OnCreate method


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_task);
        //db is a variable of type TaskerDbHelper
    db=new TaskerDbHelper(this);
    list=db.getAllTasks();
    adapt=new MyAdapter(this,R.layout.list_inner_view , list);
    ListView listTask=(ListView)findViewById(R.id.listView1);
    listTask.setAdapter(adapt);
}
 

Next up is listing all the tasks in the list view and refreshing when ever a task is added. So in the xml finle don't forget to declare the listener for button then add the following method to activity

So after adding task we can see this

Lastly we need to change status of task when the checkbox against it is checked. This is a complicated bit as we will need the ID of task which was checked and then proceed. So here is what we are going to do we are going to visit our adapter again and add a listener over there.

So here is the updated complete code of the activity.

Now the finally when we check the checkbox our database will reflect changes as this

And the task will be checked

So that is it for now folks. Hope you enjoyed this tutorial. I had fun making it!!! With some more work it can be turned into a full fledged check-list for you.

The project source code is attached with the tutorial, download the Eclipse Project from there.

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