What is the difference between i++ & ++i in a for loop? [duplicate]

I've just started learning Java and now I'm into for loop statements. I don't understand how ++i and i++ works in a for-loop.

How do they work in mathematics operations like addition and subtraction?

They both increment the number. ++i is equivalent to i = i + 1.

i++ and ++i are very similar but not exactly the same. Both increment the number, but ++i increments the number before the current expression is evaluted, whereas i++ increments the number after the expression is evaluated.

int i = 3;
int a = i++; // a = 3, i = 4
int b = ++a; // b = 4, a = 4

Here's a sample class:

public class Increment
{
    public static void main(String [] args)
    {
        for (int i = 0; i < args.length; ++i)
        {
            System.out.println(args[i]);
        }
    }
}

If I disassemble this class using javap.exe I get this:

Compiled from "Increment.java"
public class Increment extends java.lang.Object{
public Increment();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return

public static void main(java.lang.String[]);
  Code:
   0:   iconst_0
   1:   istore_1
   2:   iload_1
   3:   aload_0
   4:   arraylength
   5:   if_icmpge       23
   8:   getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   11:  aload_0
   12:  iload_1
   13:  aaload
   14:  invokevirtual   #3; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   17:  iinc    1, 1
   20:  goto    2
   23:  return

}

If I change the loop so it uses i++ and disassemble again I get this:

Compiled from "Increment.java"
public class Increment extends java.lang.Object{
public Increment();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return

public static void main(java.lang.String[]);
  Code:
   0:   iconst_0
   1:   istore_1
   2:   iload_1
   3:   aload_0
   4:   arraylength
   5:   if_icmpge       23
   8:   getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   11:  aload_0
   12:  iload_1
   13:  aaload
   14:  invokevirtual   #3; //Method java/io/PrintStream.println:(Ljava/lang/String;)V
   17:  iinc    1, 1
   20:  goto    2
   23:  return

}

When I compare the two, TextPad tells me that the two are identical.

What this says is that from the point of view of the generated byte code there's no difference in a loop. In other contexts there is a difference between ++i and i++, but not for loops.