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AP Computer Science
Lab 10 a, b, c
Command Line Arguments, Exception Handling
Directions: These labs can go into a NEW project folder called Semester 2 (this folder is
separate from your Comp Sci Intro project folder). Save this new project folder under
your server folder (NOT the classroom folder).
Lab10a.java
Part 1: Summing integers
Write a program that passes an unspecified number of integers as one commandline argument and display their total. Use main (String [] args). At runtime, the
argument list on the command line will be “1 2 3 4 5” and the program will figure
out the total.
Example: java Lab8 “1 2 3 4 5”
The total is 15
Have all of this happen within a menu that the user can only exit if they select Q for
quit. (The menu can be short: P for new phrase and Q for quit.) You should use a
method to total the integers in the argument. You can decide if the method is void
or not.
You will need to tokenize the string (using a “ “ as the delimeter), and put each token
into a temporary string, tempStr. Then convert this tempStr to an integer. Google
“java string to integer” and look for the parseInt method. It returns an integer, and
has a String (use tempStr) in the argument list.
Do not worry about catching user errors yet, besides the menu options. We will
have error handling into the lab tomorrow.
Part 2: Exception Handling
Edit Part 1 of Lab 10a (parsing integers taken from the command line argument).
Create/include a try-catch block to trap the error that occurs if the string contains
non-integers. Print a Java-generated message if an error occurs. Find the sum of the
other integers in the input string.
Example:
Input: java Lab8 “1 2 3 4 5”
Output: A NumberFormatException occurred. Please enter a phrase that contains
numbers only next time. The total is 15.
Lab10b.java
Write a program that meets the following requirements:
1. Create an array with 50 randomly chosen integers, between 1 and 50.
2. Prompt the user for an array index value and display the contents of the array at that
index value. Assume that the end-user knows that arrays are indexed from 0, so an input of
0 to 49 would be valid.
3. Trap the error if the user specifies an index that is out of bounds, and print a Javagenerated error message. Re-prompt after the error.
Lab10c.java
Experiment with dividing by zero with integers and floats. Catch the exception for
divide-by-zero error with integers. Experiment with dividing by zero with doubles.