CS-151 Labs > Lab 3. My ArrayList

Part 4. Performance tests

Great! You are done with your implementation, and you have written some JUnit tests to make sure that each method works as expected. Hopefully everything is being added, set, and removed correctly. The last thing we want to quickly check is that our program is working efficiently. Add the following three tests to your test file (precede the method header with the @Test tag):

void testAddEfficiency()

Create a test program that inserts 1,000,000 Integers starting at 1 onto the end of the list (using the single-parameter add). Every 10,000 adds, print out the value. Note the speed with which the program completes. Now insert the same Integers but onto the front of the list. Does the speed change? Why or why not?

You may want to change this method’s @Test tag to an @Ignore tag before proceeding. This will indicate to JUnit to ignore this test for the time being (which is good, because it takes awhile to run.)

void testRemoveEfficiency()

As with the previous test, insert 1,000,000 Integers starting at 1 onto the end of the list (using the single-parameter add). Now remove all the elements from the back of the list (printing out the value every 10,000 removes). This should run quickly (and if not, take another look at your remove method).

void testMemory()

Finally, create a test method that stores Integers and have it store values starting with 1 until it runs out of memory or throws an exception (use an infinite loop). Every 10,000 adds, print out the value. Note what the last value printed was. Now run it again telling it to use more memory and notice if the value changes or not. You can tell Eclipse to use more memory by clicking Run > Run Configurations…, clicking on the Arguments tab, and inserting -Xmx500m in the VM arguments textbox.

Pay attention to the rate at which testMemory() prints out numbers. Do you notice any changes? Run it again. Does it behave the same? Why do you think this is happening?

Please put your answers to the above questions into your readme file, and submit it with the lab.

After you have completed these efficiency tests, please put @Ignore in front of the @Test to disable them.