Recitation 19 for CS160

Recitation R11 - The Library Class
Summer 2016

CS160: Foundations in Programming

Data

Declare an array of Music objects called arrayTitles as a public static class variable.

Implement the readLibrary Method

Implement a public static method called readLibrary which takes a String parameter called fileName and returns nothing.
Implement readLibrary as follows:
- Add a Scanner that reads from the file whose name is passed in to the method.
- In the catch block, print an error message and exit the program.
read in the fhe first line of the file as an integer called size. This indicates the number of Music objects.
Use size it to allocate the class variable arrayTitles.
Add a for or while loop that reads the remaining lines of the file.
The format of the file is 4 lines per entry: title, album, artist, year.
Create a Music object of each entry and store it in arrayTitles.

NOTE: Even after allocating the array, you must instantiate each individual Music object (by calling the constructor) for each array element.
WARNING: After each call to nextInt() you must add a nextLine() call to discard the newline that follows the integer, otherwise the next String you read may be empty.
Add print statements if necessary to make sure you are reading all the data correctly.

Test the readLibrary Method

Call readLibrary from your main with args[0] as the parameter.
- Do not hard-code the file name, use the name passed in as a parameter.
Here is the data file that you will read for this program: music.txt

Add a loop that iterates the array of Music objects and prints each element. Add a track number in front of each object, followed by a colon and space. In addition, keep track of the total cost of the titles, and print it at the end, in the format shown. The console output should be as follows:

1: Brown Eyed Girl, Blowin' Your Mind!, Van Morrison, 1967
2: Stop Putting the Hurt on Me, Lucille, B. B. King, 1968
3: Another Brick in the Wall, The Wall, Pink Floyd, 1979
4: Funeral for a Friend, Goodbye Yellow Brick Road, Elton John, 1973
5: Beat It, Thriller, Michael Jackson, 1982
6: Like a Virgin, Like a Virgin, Madonna, 1984
7: So Far Away, Brothers in Arms, Dire Straits, 1985
8: Try a Little Tenderness, Swamp Boogie Queen, Katie Webster, 1990
9: Hey Jack Kerouac, MTV Unplugged, 10,000 Maniacs, 1993
10: Mockingbird, Encore, Eminem, 2005
11: Jackdaw, Draw the Line, David Gray, 2009
12: Someone Like You, 21, Adele, 2011
Number of Tracks: 12
Total cost: $13.78

Implement the Rest of the Methods

Add a public static method writeLibrary that takes a String parameter with the output filename and returns nothing:
- Call writeLibrary from your main (after readLibrary) with args[1] as the parameter.
- Do not hard-code the file name, use the name passed in as a parameter.
- To implement writeLibrary, open a PrintWriter and copy the code from main that iterates the array of Music objects. You should get the same output as in the main method, except this method will send the output to a file (remember, you will need to use your PrintWriter object instead of System.out).
```
1: Brown Eyed Girl, Blowin' Your Mind!, Van Morrison, 1967
2: Stop Putting the Hurt on Me, Lucille, B. B. King, 1968
3: Another Brick in the Wall, The Wall, Pink Floyd, 1979
4: Funeral for a Friend, Goodbye Yellow Brick Road, Elton John, 1973
5: Beat It, Thriller, Michael Jackson, 1982
6: Like a Virgin, Like a Virgin, Madonna, 1984
7: So Far Away, Brothers in Arms, Dire Straits, 1985
8: Try a Little Tenderness, Swamp Boogie Queen, Katie Webster, 1990
9: Hey Jack Kerouac, MTV Unplugged, 10,000 Maniacs, 1993
10: Mockingbird, Encore, Eminem, 2005
11: Jackdaw, Draw the Line, David Gray, 2009
12: Someone Like You, 21, Adele, 2011
Number of Tracks: 12
Total cost: $13.78
    
```
- Your output file should match this exactly.
- The format above has a number for each title, starting at 1 and ending at the last number. Each field is separated by a comma and space, but there is no trailing comma or space.
- Make sure that your program correctly writes all of the data in the input file to the output file.
- Add code to writeLibrary figure out how much it would cost to buy all the titles in the file by iterating the array of Music objects and calling getPrice for each element. You must accumulate the total cost in a variable. Write the message below to the output file using printf() to ensure 2 digits after the decimal point in the total cost.
Implement a public static method searchTitles that takes a String parameter and returns nothing. This method should print all the tracks that contain that String.
(Hint: use the java documentation to look up the .contains method in the String class)
- This method will print in the same order and format as before, but will only print the titles containing the search string.
Implement a public static method called sortTitles that has no parameters and returns nothing. This method shoudld sort the array by song title. You can do this by creating a for loop that iterates over all the uppercase letters and prints only the titles that start with that letter. Note that the resulting output is sorted only by the first letter, and is not completely alphabetized.
- This method will print in the same format as before, but in the sorted order.

Recitation R11 - The Library Class Summer 2016

Data

Implement the readLibrary Method

Test the readLibrary Method

Implement the Rest of the Methods

Recitation R11 - The Library Class
Summer 2016