To compare the performance of adding to Java's Linked Lists vs. Array Lists
For this Lab, you will be writing code to compare the performance of adding data to Java's built-in LinkedList and ArrayList classes. We will be adding data to the beginning and end of both of these data structures and timing how long it takes to run these programs.
To time a program on the command line, simply prefix the command
with the word
time. This will run the command you give
and report how long it took to execute. For example:
$ time java Program real 0m18.625s user 0m18.520s sys 0m0.052s
time command outputs the time in three categories. The one
we care about is the "real" time, which is the first row. This refers to how
much actual time has elapsed during execution.
"User" and "sys" time refer to how much time was spent executing "user" code vs. "system code. When a program makes calls to the operating system (such as to print to the terminal or allocate memory) that is counted separately. Also the user and sys time could be more than real time if we had used multiple threads, since it counts time used on a CPU.
So look at the "real" time when making these comparisons.
It's possible that trying to make a list of the 5 million numbers will be too much for your Java VM. If you get an error like this:
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
Then you will need to increase the maximum size of the heap. That can be done by passing the -Xmx flag to the java command, followed by the size you want. For example, passing a maximum of 4 gigabytes should be plenty. Run your program like this to achieve that:
$ java -Xmx4g ProgramName
For this lab, you can fill out the following table of times:
Also, answer the following questions:
When you're finished, email the table (which can just be in the text of an email), and your answers to the three questions to firstname.lastname@example.org.
Copyright © 2019 Ian Finlayson | Licensed under a Creative Commons Attribution 4.0 International License.