Ternary Operator (If-Then-Else)

You can use the ternary operator for performing if-then-else conditional logic inside the expression. The following listing shows a minimal example:

Java

String falseString = parser.parseExpression(
    "false ? 'trueExp' : 'falseExp'").getValue(String.class);

In this case, the boolean false results in returning the string value 'falseExp'. A more realistic example follows:

Java

parser.parseExpression("name").setValue(societyContext, "IEEE");
societyContext.setVariable("queryName", "Nikola Tesla");

expression = "isMember(#queryName)? #queryName + ' is a member of the ' " +
    "+ Name + ' Society' : #queryName + ' is not a member of the ' + Name + ' Society'";

String queryResultString = parser.parseExpression(expression)
    .getValue(societyContext, String.class);
// queryResultString = "Nikola Tesla is a member of the IEEE Society"

See the next section on the Elvis operator for an even shorter syntax for the ternary operator.