Lab 13
Logistics
- Due: on Thursday, December 1st anywhere on earth (6am Friday). (Penalties from the syllabus apply if you turn it in any later.)
- Submission instructions: you have two options. The first option is to demonstrate the execution of your lab to your TA during your assigned lab section on Thursday. The second option is to submit your Java file(s) on D2L.
Learning outcomes
- Understand merge sort
- Practice Java file I/O
Assignment
In this assignmemt, you will write a method implementing merge sort and use it to sort the lines of a file two ways: alphabetically and by the length of the line. To do so, you will also implement your own comparator.
Starter code:
Merge sort
In the Demo.java file, implement merge sort recursively and so that it can be used for any type. Consult Wednesday’s lecture. If you would like, you can look at the book’s implementation, but try to understand how it works even if you just copy it in.
Length comparator
Your merge sort function takes in a Comparator object. In the LengthComparator.java file, write your own comparator that takes in two strings and returns -1 if the second is longer, 1 if the first is longer, and 0 if they are equal. You can look at the book’s implementation if you would like.
Reading and writing from a file
Consult the example code from Monday to learn how to read and write from a file. Then, download Housman.txt, put it in your project directory (in Eclipse, that is in /yourHome/eclipse-workspace/projName/putFileHere, but ask a TA or on Discord for help if you can’t figure out where to put your file). In Demo.java, read the contents into an array and write two new files: sortedbyAlpha.txt and sortedByLength.txt.
Here are examples of what your output files should look like:
Grading - 10 points
- 3 points - merge sort is correct
- 3 points - length comparator is correct
- 2 points - reads from file
- 2 points - writes to file
Grading turnaround
This lab will be graded with scores in Brightspace before Tuesday, December 6th.