The ? : operator in Java

The conditional operator only works for assigning a value to a variable, using a value in a method invocation, or in some other way that indicates the type of its second and third arguments. For example, consider the following

if (name.equals("Rumplestiltskin")) {
  System.out.println("Give back child");
}
else {
  System.out.println("Laugh");
}

This may not be written like this:

name.equals("Rumplestiltskin") 
 ? System.out.println("Give back child") 
 : System.out.println("Laugh");

First of all, both the second and third arguments are void. Secondly, no assignment is present to indicate the type that is expected for the second and third arguments (though you know void must be wrong).

The first argument to the conditional operator must have or return boolean type and the second and third arguments must return values compatible with the value the entire expression can be expected to return. You can never use a void method as an argument to the ? : operator.