what's the integer value for boolean "true"?

[Mindy Wu]

The following example seems to me that boolean value "true" has a value "0" and boolean value "false" has ? (I am not sure is 1 or -1).
public class test1 {
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);
}
}
The result is 1, but if I change x=false, then the result is 4.
Can anyone clearify me for this?
Thanks!
Mindy

[Manfred Leonhardt]

Hi Mindy,
In java, boolean values represent truth values true and false. They are given no numeric values and the compiler will not let them be used as such ...
Let's walk through your example. You seem to be having problems understanding the conditional operator. The code below

if(x)
  a = x ? 1 : 2;
else
  a = x ? 3 : 4;

can be written long hand as show below.

if( x )
{          // Line 1
  if( x )
  {
    a = 1; // Line 2
  }
  else
  {
    a = 2; // Line 3
  }
}
else
{           // Line 4
  if( x ) 
  {
    a = 3;  // Line 5
  }
  else
  {
    a = 4;  // Line 6
  }
}

When we go through the code for x = true we get:
Line 1 --> true so run this section
Line 2 --> true so set a = 1;
When we go through the code for x = false we get:
Line 1 --> false so skip section
Line 4 --> true because Line 1 false
Line 6 --> true so set a = 4
The code doesn't show anything about the numeric value of boolean , it is just an exercise for conditional operators.
Regards,
Manfred.

[Mindy Wu]

Thank so much for your clear explaination, Manfred Leonhardt!

Mindy