Test some Java loop optimization cf. http://pastebin.com/4edtQXmV

TestOptimizations.java

public class TestOptimizations {

	private static final String str = "abcdefg";
	private static long nothing = 0;
	
	public static void main(String[] args) {
		
		// try swapping the order of these first two calls.
		System.out.println("inline (ms): " + runLoopInline(10000000));
		System.out.println("precalc (ms): " + runLoopPrecalc(10000000));
		
		
		System.out.println("precalc  (ms): " + runLoopPrecalc(20000000));
		System.out.println("inline (ms): " + runLoopInline(20000000));
		
		System.out.println("precalc (ms): " + runLoopPrecalc(30000000));
		System.out.println("inline (ms): " + runLoopInline(30000000));
		
	}

	private static long runLoopInline(int numTests) {
		
		long blah = 0;
		long start = System.currentTimeMillis();
		
		for (int j = 0; j < numTests; j++) {
			for (int i = 0; i < str.length(); i++) {
				blah = 2*i*j;
			}
		}
		
		nothing = blah; // try commenting this out...
		return System.currentTimeMillis() - start;
	}
	
	private static long runLoopPrecalc(int numTests) {
		
		long blah = 0;
		int length = str.length();
		
		long start = System.currentTimeMillis();
		
		for (int j = 0; j < numTests; j++) {
			for (int i = 0; i < length; i++) {
				blah = 2*i*j;
			}
		}
		
		nothing = blah; // try commenting this out...
		return System.currentTimeMillis() - start;
	}

}