What does this mean: "int x = true ? 10 : 20 ; "

[Thomas Markl]

class XTC20 {
public static void main ( String [ ] args ) { // ---> line 1
int x = true ? 10 : 20 ; // ---> line 2
System . out . println ( x ) ; // ---> line 3
}
};
What does code in line 2 mean?

[kevin comario]

booleanExpression ? expression1 : expression2;
expression1 is your answer if the booleanExpression is true else it is expression2.
Its a conditional statement, an if else statement.
[ November 08, 2002: Message edited by: kevin comario ]

[Erik Pragt]

It means: if condition is true, than asign the first value after the question mark to the variable, else the second. The condition is BEFORE the question mark, so the layout looks like this:
int x = <condition> ? <assign value to x if condition is true> : <assign value to x if condition is value>
In your case this would mean:
if true = true then x is 10, else x = 20. In your case x = always 10, because true is always true.
An example that would make (a little) more sense is this one

class XTC20 
{
  public static void main ( String [ ] args ) 
  { 
    int x = if(args[0].equals("10") ? 10 : 20 ; // ---> line 2
    System . out . println ( x ) ; // ---> line 3
  }
};

if you compile (javac XTC20) it, you can run it like this:
> java XTC20 10
output will be 10
> java XTC20 20
output will be 20
> java XTC20 30
output will be 20

have fun!
Erik

[Dirk Schreckmann]

The "query-colon" operator (which is a short hand if-else operator) is Java's only ternary operator.
http://java.sun.com/docs/books/tutorial/java/nutsandbolts/operators.html

[jiang jiangwei]

conditionExpression?
executeExpression1:
executeExpression2
if the "conditionExpression" is true then run the
"executeExpression1" else run latter.
executeExpression is not only value ,it also could be function.

[James Chegwidden]

It is called a conditional or ternary operator because it requires three operands and two operators. C and C++ have is functionality as well.