Compare boolean to integer

[Susie Chow]

Hi, can anyone explain to me why the following prints 1? Thank you.
public static void main(String[] args)
{
boolean x = true;
int a;
if(x) a=x? 1:2;
else a=x? 3:4;
System.out.println(a);
}

[William Brogden]

That is amazing - seems to me it should produce a compiler error but it does compile and run as you said.
public class TestB {
public static void main(String[] args)
{
boolean x = true;
int a;
if(x) a=x? 1:2;
else a=x? 3:4;
System.out.println(a);
System.out.println( a=x ); // causes expected compiler error
}
}
Bill

[Christophe Lee]

a = x ? 1 : 2;
just means
if (x)
a = 1;
else
a = 2;
therefore, expanding your code would look like:
if(x) //true)
{ if(x) //true
a = 1; //a gets assigned to 1
else
a = 2;
}
else //never executes this
{}
System.out.println(a) //prints 1

[Anshul Manisha]

Java ternary operator(conditional operator) has higher precedence than assignment operator so x?1:2 is evaluated first and then the value is assigned to a

[lashkar]

you posted:
p s v main (S ar[]){
boolean x = true;
int a;
if(x) a=x? 1:2;
else a=x? 3:4;
System.out.println(a);
}
=====
even though a is not initialized ,as you are not fetching the value of a , it compiles AND at runtime when the Statemnt assigns 1 to a , it does not check whats the previous value is ,ruther simply reWrites .
BUT if you test as follows ,
public static void main(String[] args)
{
boolean x = true;
int a;
System.out.println(a);
if(x) a=x? 1:2;
else a=x? 3:4;
}
compiler complains " a has not been init " .

[Anshul Manisha]

What is your point Lashkar???

[Jane Griscti]

Lashkar,
Please read the JavaRanch Name Policy and re-register using a name that complies with the rules.
Thanks for your cooperation.
------------------
Jane Griscti
Sun Certified Programmer for the Java� 2 Platform