This post originated from an RSS feed registered with Java Buzz by Simon Brown. Original Post: Object instantiation in Java is fast! Feed Title: Simon Brown's weblog Feed URL: http://www.simongbrown.com/blog/feed.xml?flavor=rss20&category=java Feed Description: My thoughts on Java, software development and technology. Latest Java Buzz Posts Latest Java Buzz Posts by Simon Brown Latest Posts From Simon Brown's weblog

I'm putting together a prototype for a file adapter component at the moment that reads in a file containing hundreds of thousands of rows and dispatches each item in the file for processing. Out of curiosity I ran some benchmarks on my work PC - a Pentium 4, 2Ghz, 1Gb RAM running Windows XP. Reading a file containing 200,000 lines with a BufferedReader takes less than a second using the original java.io libraries. Pretty quick, and I wonder how long the file would take to read in with memory-mapped files in NIO.

However, what really interested me was the overhead incurred by wrapping each line in the file inside a new object. The reason for doing this was so that each line looked like a domain object, making it cleaner to pass around and easier extract information. So, after commenting out this object instantiation, I re-ran the benchmark. It only took <100ms off the total time to run the program. I am amazed! Only <100ms to create 200,000 objects.

As a test I ran the following code.

    long start = System.currentTimeMillis();
    for (int i = 0; i < 200000; i++) {
      Integer x = new Integer(i);
    }
    long end = System.currentTimeMillis();
    System.out.println(end-start);