Question

Q) MyBooks is an android application has a homepage "Activity_MyBooks.xml" that shows a simple list. This list displays only the book title for each book in the user’s book database. The database has a table name “Books” which has the following fields (Book_id, BookTitle, Author, Year). This App connected to the Database by BookstDataSource class and BooksDBHelper class.

Explain the following questions on your own words and no need to write a code.

1. Explain how to create the Layout for the list in MyBooks App?

2. Explain the steps of creating the Data Source method for the list in MyBooks App?

Answers

1. Creatint the Layout for the list

Two components are required for any list implementation in Android: a ListView widget and an adapter. The ListView widget is an object that can display a vertical list of items that can be scrolled through. An Adapter is dynamically associated with the ListView. The adapter provides access to the underlying data source for the list.

• The visible component of a list is implemented with a ListView widget in an XML layout file. In many ways, a ListView is a standard widget. However, if given the special ID of @id/android:list and a special subclass of Activity , many of the tasks of list implementation are easier because the developer can take advantage of many built-in features of the SDK. To take advantage of these features, the Activity associated with the layout containing the ListView must be a subclass of ListActivity rather than Activity.
• Lists require the use of an adapter. The adapter provides access to the data items and is responsible for creating a View for each item.

2. Creating the Data Source method

The first step to implementing the simple list is to have data. For this, we need to add a method to the “BookstDataSource” class that will retrieve each item.

The primary function is that the query can return more than one record to the cursor, so we have to implement a loop to retrieve all the records.

1. The return value for this method is an ArrayList . An ArrayList is an object that acts like an array in that the data it holds can be accessed through an index. In contrast to an array, the ArrayList is not a fixed size. It can grow as data is added to it. An ArrayList is parameterized. So if we use <String> portion of the code. This says that the values in the ArrayList are all of the String data type. So, this can be used to display book title field
2. The SQL query is set up to return the fields for all records in the Books table.
3. A loop is set up to go through all the records in the cursor. The loop is initialized by moving to the first record in the cursor. Next, the while loop is set up to test if the end of the cursor’s record set has been reached. Within the loop, the book title is added to the ArrayList, and the cursor is advanced to the next record.
4. The ArrayList is set to a new empty ArrayList in case the routine crashes partially through its filling. This way, the calling Activity can test for an empty list to determine if the retrieve was successful.

Note: I need only to paraphrase the Answer . So its does not match the answers with other students

Answer 1

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