performance - Java JRE vs GCJ

Question

I have this results from a speed test I wrote in Java:

Java

real        0m20.626s
user        0m20.257s
sys         0m0.244s

GCJ

real        3m10.567s
user        3m5.168s
sys         0m0.676s

So, what is the purpose of GCJ then? With this results I'm sure I'm not going to compile it with GCJ!

I tested this on Linux, are the results in Windows maybe better than that?

This was the code from the application:

public static void main(String[] args) {
    String str = "";
    System.out.println("Start!!!");
    for (long i = 0; i < 5000000L; i++) {
        Math.sqrt((double) i);
        Math.pow((double) i, 2.56);
        long j = i * 745L;
        String string = new String(String.valueOf(i));
        string = string.concat(" kaka pipi"); // "Kaka pipi" is a kind of childly call in Dutch. 
        string = new String(string.toUpperCase());
        if (i % 300 == 0) {
            str = "";
        } else {
            str += Long.toHexString(i);
        }
    }
    System.out.println("Stop!!!");
}

I compiled with GCJ like this:

gcj -c -g -O Main.java
gcj --main=speedtest.Main -o Exec Main.o

And ran like this:

time ./Exec                     // For GCJ
time java -jar SpeedTest.jar    // For Java

Answer 1

GCJ is obsolete. It was started a long time ago because people wanted an open-source alternative to the Sun JDK, and it was never particularly good. Now that Sun open-sourced their JDK, there's absolutely no reason to use GCJ (but it still lurks in some Linux distros).