Simple Question regarding autoincrement operator in Java

Question

Hi, I know that from C/C++, autoincrement operator has a different meaning depending on where it is applied (eg: integer = i++ vs. integer = ++i).

In Java do the following two statements mean the same thing?

int i = 1

driverVO.setUid(String.valueOf(i++)); //1?

driverVO.setUid(String.valueOf(++i)); //2?

Answer 1

int x = 1;    
System.out.println(++x); // prints 2


int y = 1;
System.out.println(y++); // prints 1

Answer 2

Groovy Shell (1.6.0, JVM: 1.6.0_05)
Type 'help' or '\h' for help.
-----------------------------------------------------
groovy:000> i=0
===> 0
groovy:000> j=0
===> 0
groovy:000> i++
===> 0
groovy:000> ++j
===> 1
groovy:000>

They operate as they do in C. Groovy is awesome for executing quick java tests.

(And yes, I realize they made some minor changes, but for the most part, if you execute Java code in groovy, it will execute just as it does in Java)

Answer 3

In the first example, i will be incremented AFTER the rest of the statement.

In the second example, i will be incremented BEFORE it.

Answer 4

There is also a implementation difference between these two operators.

i++ ->It first copies a value of i to a temporary space, increments i and returns the saved value.

++i->Increments the value and returns it.

I might be wrong on that but using the second one will probably have better performance (Especially if i is an object).