What is the difference between & and && in Java?

Question

I always thought that && operator in Java is used for verifying whether both its boolean operands are true, and the & oper

Answer 1

I think my answer can be more understandable:

There are two differences between & and &&.

If they use as logical AND

& and && can be logical AND, when the & or && left and right expression result all is true, the whole operation result can be true.

when & and && as logical AND, there is a difference:

when use && as logical AND, if the left expression result is false, the right expression will not execute.

Take the example :

String str = null;

if(str!=null && !str.equals("")){  // the right expression will not execute

}

If using &:

String str = null;

if(str!=null & !str.equals("")){  // the right expression will execute, and throw the NullPointerException 

}

An other more example:

int x = 0;
int y = 2;
if(x==0 & ++y>2){
    System.out.print(“y=”+y);  // print is: y=3
}

---

int x = 0;
int y = 2;
if(x==0 && ++y>2){
    System.out.print(“y=”+y);  // print is: y=2
}

& can be used as bit operator

& can be used as Bitwise AND operator, && can not.

The bitwise AND " &" operator produces 1 if and only if both of the bits in its operands are 1. However, if both of the bits are 0 or both of the bits are different then this operator produces 0. To be more precise bitwise AND " &" operator returns 1 if any of the two bits is 1 and it returns 0 if any of the bits is 0. 

From the wiki page:

http://www.roseindia.net/java/master-java/java-bitwise-and.shtml