gistfile1.txt

alex@jupiter:~$ cat Foo.java 
public class Foo {
    public static void main(String[] args) {
        String blah = "foo";

        for (int i = 0; i < 10; i++) {
            blah += i;
        }

        System.out.println(blah);
    }
}
alex@jupiter:~$ javac Foo.java 
alex@jupiter:~$ javap -c Foo
...
   19:	invokevirtual	#5; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   22:	iload_2
   23:	invokevirtual	#6; //Method java/lang/StringBuilder.append:(I)Ljava/lang/StringBuilder;
...