4

Possible Duplicate:
& vs && and | vs ||

What is the difference between & and &&?

I am getting same output for both & and &&.

Ex:

  1. &&:

    if (true && true){
    System.out.println("------if------");
} else {
    System.out.println("------else------");
}

  2. &:

    if (true & true){
    System.out.println("------if------");
} else {
    System.out.println("------else------");
}

Output:

  1. ------if------
  2. ------if------

Can we use & and && operators in our code interchangeably?

Cœur
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Satya
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    See http://stackoverflow.com/questions/1795808/and-and-or-in-java-if-statements and http://stackoverflow.com/questions/4014535/vs-and-vs – Nivas Oct 13 '11 at 12:28

8 Answers8

2
  • & - bitwise AND
  • && - logical AND

You've true in both cases because in case of logical AND reason is obvious and in case of bitwise AND - true is interpreted as 1, so 1 & 1 alsays returns 1 which turns out into logical true

sll
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  • `&` works fine for booleans too. The operands are not "interpreted" as integers. – aioobe Oct 13 '11 at 12:27
  • +1 for being the only real right answer here. & and && are actually two different operators. If I recall correctly, the fact that one uses full boolean eval and the other no, is just a side effect. you can use &= but I don't think you can use &&= in java. – BigMike Oct 13 '11 at 12:31
2

&& short circuits the evaluation, while & always evaluates both operands.

This is a duplicate question. I'll try to dig out the link for you...

Community
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aioobe
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2

& will force the evaluation of both the left and right operands whereas && is the short-circuit operator and doesn't check the right operand in obvious cases.

// this will evaluate both method calls even if the result
// of checkSomething() is false
boolean result = checkSomething() & checkSomethingExpensive()

// this will skip evaluation of checkSomethingExpensive() if the result of
// checkSomething() is false
boolean result = checkSomething() && checkSomethingExpensive()
Sanjay T. Sharma
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0

logical AND &&

Java operators

The bitwise & operator performs a bitwise AND operation.

Java operators2

Markus Lausberg
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0

Rule of thumb : use && when dealing with booleans, conditions, ifs, etc. I.e. most of the time. Use & in the rare cases when you need to perform bits operations.

solendil
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0
  • &: operation, boolean true & true == true, integer 1001b & 1110b == 1000b
  • &&: comparison, boolean true & true == true, integer compiler error
Sibbo
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0

That's because the following is evaluated:

I will write it in english semantic for you to understand.

For output 1: Logical AND &&

if true AND true IS TRUE.

For ouptut 2: Bitwise AND &

  • Let x = true (in other words, bit 1)
  • x = x AND true (in other words, x = 1 & 1) Bit is AND'ed
  • if (x IS TRUE) then print the if statement.
Buhake Sindi
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-1

&& is a comparison while & is an operation!

Meister Schnitzel
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