From charlesreid1

If you want an extremely detailed picture of how much time you're spending in the various parts of your code, you can use a profiler: see Java/Profiling

Basic Timing in Java: Builtin Methods

If you just want to see how much time a piece of code takes to execute, you can use Java's built in time functionality:

long start = System.nanoTime();
long end = System.nanoTime();
long duration = end - start;
System.out.printf("Elapsed time: %03f s\n", duration/1E9);

Timing Snippets of Code

Can make a Stopwatch class that does the following:

  • Constructor creates a new "start" variable - the stopwatch class measures time starting at its own creation
  • Can call elapsed() method to get elapsed seconds


public class Stopwatch {
    public Stopwatch() { 
        this.start = System.currentTimeMillis();
    public double elapsed() {
        this.end = System.currentTimeMillis();
        return (end-start)/1000.0;

Comparing Hombrew Data Containers to Java Collections API

In the Java repository (link) in the lists/linked-lists folder (link), there is a timing script (link) that demonstrates a simple comparison of the built-in linked list type to a trimmed down generic TLinkedList type (link).

See Linked Lists/Java/Timing for a timing comparison of the Collections Linked List type and a hand-rolled, generic Linked List type.

LinkedListProfiling Add.png

LinkedListProfiling AddRemove.png

Demonstrations of the O(1) behavior of adding, and randomly adding/removing, using a linked list.