- The Spring Expression Language (SPEL) supports a wide range of operators that allow you to perform various operations on data, evaluate conditions, and manipulate expressions. Here is an overview of the operators available in SPEL:
Arithmetic Operators:
- +: Addition
- -: Subtraction
- *: Multiplication
- /: Division
- %: Modulus (Remainder)
#{
10 + 5, // 15
20 - 8, // 12
4 * 3, // 12
15 / 2, // 7.5
17 % 4 // 1
}
Relational Operators:
- ==: Equal to
- !=: Not equal to
- <: Less than
- <=: Less than or equal to
- >: Greater than
- >=: Greater than or equal to
#{
5 == 5, // true
10 != 7, // true
8 < 12, // true
15 <= 15, // true
20 > 25, // false
30 >= 30 // true
}
Logical Operators:
- and, &&: Logical AND
- or, ||: Logical OR
- not, !: Logical NOT
#{
true and false, // false
true or false, // true
not true, // false
true && (false || true) // true
}
Conditional (Ternary) Operator:
- ? :: Conditional operator, similar to the Java ternary operator.
#{
(5 > 3) ? "Yes" : "No", // "Yes"
(2 == 2) ? "A" : "B" // "A"
}
Instanceof Operator:
- instanceof: Checks if an object is an instance of a specific class or interface.
#{
'Hello' instanceof String,
// true
new ArrayList() instanceof List
// true
}
Safe Navigation Operator:
- ?.: Used to safely navigate through potentially null object references, avoiding null pointer exceptions.
#{
someObject?.getProperty(),
someObject?.list?[0]
// If someObject or the list is null,
this expression returns null
}
Elvis Operator:
- ?:: Also known as the null-safe operator, it provides a default value if the expression on the left is null.
#{
someValue ?: defaultValue, //
If someValue is null, this expression
returns defaultValue
(nullValue != null) ? nullValue
: defaultValue
// Same as above
}
These operators make SPEL a powerful language for working with expressions, making decisions, and manipulating data within the Spring Framework. They are commonly used in Spring configurations, annotations, and expressions to handle dynamic values and conditions.
