doubt on "?" operator

[ansuman mohapatra]

Hi,

I am completely lost on the following question


1. public class Test {
2. public static void main(String[] args) {
3. boolean b = false;
4. String s = (b=!b)?(b=!b)?"Hello":"hello" b=!b)?"world":"World";
5. System.out.println(s);
6. }
7. }

answer is hello...

i don understand how come hello is coming although it will be coming as

String s = true ? false? "Hello":"hello" so true or false should yield true rite...then "Hello" should come

and about the 2nd part im not able to get it how its operating.

please clarify

[Kishore Kumar]

Hi,
boolean b = false;
String s = (b=!b)?(b=!b)?"Hello":"hello" b=!b)?"world":"World";

Terinary operators have assositivity from Right to left.
So, the above expression becomes

String s = (b=!b)?((b=!b)?"Hello":"hello") (b=!b)?"world":"World");
So first, this executes:-((b=!b)?"world":"World")
Result is: world and boolean b = true.
Expression becomes:
String s = (b=!b)?((b=!b)?"Hello":"hello"): world
Now, (b=!b)?"Hello":"hello" executes:
Result is: hello and boolean b = false.
So expression becomes: String s = (b=!b)? "hello":"world"
Finally out put is: hello.

I hope i explained clearly.

[Ashok Pradhan]

Is that your expression :-

String s = (b=!b)?(b=!b)?"Hello":"hello":"World";

if this then it is evaluted as:

if(b=!b)
{
if(b=!b)
{
s="Hello";
}
else
{
s="hello";
}
}
else
{
s="World";
}

Is that helpfull !!!

[Prabhat Gupta]

boolean b = false;
String s = (b=!b)?(b=!b)?"Hello":"hello" b=!b)?"world":"World";

initially boolean b is "false". the ? operator works as
boolean-condition ? Experssion1:Expression2 ,if boolean condition is true it will evaluate the expression1 otherwise it will evaluate expression2.

Here boolean condition (b=!b) evaluated as b=!(false) =>b=true =>true
hence exprsesion1 (b=!b)?"Hello":"heelo" will be eavluated . Again here boolean condition (b!=b)will be evaluated as b=!(true)[since from last condition b is now "true" ]=>b=false =>false. Consequently the expression2 will be evaluated which is "hello",finally string s is assigned a value "hello".

hope it is clear to you.

[ansuman mohapatra]

yea dats helped..thanks