What is the difference between & and &&? [duplicate]

This question already has answers here: Closed 11 years ago.

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 {
       Sy开发者_如何学Cstem.out.println("------else------");
   }
   

Output:

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

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

---

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

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

• logical operators in java

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& 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()

---

• & - 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

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logical AND &&

Java operators

The bitwise & operator performs a bitwise AND operation.

Java operators2

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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.

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

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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.

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&& is a comparison while & is an operation!