What is the advantage of Arithmetic Assignment Operators like += over normal arithmetic operator?

[Halley Thomas]

Which is better?

a+=b;

or

a=a+b;

Can you please explain why also?

[Anupam Jain]

Halley Thomas wrote:Which is better?

a+=b;

or

a=a+b;

Can you please explain why also?

As far as I've found out and understood...
While incrementing by a variable as above... They are both same.
But if you are incrementing by some constant value say 1 like this :

i = i + 1;

and

i += 1;

Then the later one is more efficient...

This can be explained by using javap command..

javap -c <class name>

[Halley Thomas]

public class Test
	{
	public void ArithmeticAss()
		{
		int a=100;
		int b=10;
		a+=b;
		}
	public void NormAss()
		{
		int a=100;
		int b=10;
		a=a+b;
		}
	}

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

public void ArithmeticAss();
  Code:
   0:	bipush	100
   2:	istore_1
   3:	bipush	10
   5:	istore_2
   6:	iload_1
   7:	iload_2
   8:	iadd
   9:	istore_1
   10:	return

public void NormAss();
  Code:
   0:	bipush	100
   2:	istore_1
   3:	bipush	10
   5:	istore_2
   6:	iload_1
   7:	iload_2
   8:	iadd
   9:	istore_1
   10:	return

}

Found this. It means there is no improvement in performance if use the += operator if I have two variables, right?

[Anupam Jain]

Halley Thomas wrote:
It means there is no improvement in performance if use the += operator if I have two variables, right?

Yeah right... I found the same thing when using another variable b.

But try replacing b with some constant number say 1 or 2. You'll see the difference then...

[Halley Thomas]

The code when b is replaced by a constant.

public class Test
	{
	public void ArithmeticAss()
		{
		int a=100;
		a+=10;
		}
	public void NormAss()
		{
		int a=100;
		a=a+10;
		}
	}

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

public void ArithmeticAss();
  Code:
   0:	bipush	100
   2:	istore_1
   3:	iinc	1, 10
   6:	return

public void NormAss();
  Code:
   0:	bipush	100
   2:	istore_1
   3:	iload_1
   4:	bipush	10
   6:	iadd
   7:	istore_1
   8:	return

}

Yes. I'm just posting it here for others who might want to see.
Thanks a lot!

[Matthew Brown]

The only real advantage is clarity - use += if and when it makes your code easier to read. I think most people would say x += 5 is more easily read than x = x + 5, and x++ is more easily read than x += 1. Once you're used to the notation, anyway.

[Rob Spoor]

Another advantage of using += is you don't need any casting when you use bytes:

byte b = 10;
byte c = 13;
b = b + c; // compiler error: byte + byte returns an int!
b = (byte)(b + c); // works but is cumbersome
b += c; // works just fine