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2.4 Operators & Modern Control Flow

← Back to Chapter 2: Java Overview & Memory Model

Java provides standard arithmetic, bitwise, and logical control flow constructs, enriched significantly in recent LTS releases with expressive switch expressions and pattern matching.

1. Short-Circuit Logical Operators​

  • && (Logical AND): If the left operand evaluates to false, the right operand is never evaluated.
  • || (Logical OR): If the left operand evaluates to true, the right operand is never evaluated.
// Safe null-check using short-circuit evaluation
if (user != null && user.isActive()) {
    processOrder(user);
}

2. Modern Switch Expressions (Java 14+)​

The legacy switch statement was error-prone due to accidental fall-through (break omission). Modern Java introduces Switch Expressions with arrow syntax (->) and return values:

public enum OrderStatus { NEW, PROCESSING, SHIPPED, DELIVERED, CANCELLED }

public static String describeStatus(OrderStatus status) {
    return switch (status) {
        case NEW, PROCESSING -> "In preparation";
        case SHIPPED -> "Out for transit";
        case DELIVERED -> "Successfully completed";
        case CANCELLED -> {
            logCancellationAlert();
            yield "Refund pending"; // Use yield for multi-statement blocks
        }
    };
}

3. Pattern Matching for Switch (Java 21 LTS)​

Java 21 stabilizes pattern matching for switch, allowing inspection of types and null-safety directly:

public static String formatObject(Object obj) {
    return switch (obj) {
        case null -> "Null Reference";
        case Integer i -> String.format("Integer value: %d", i);
        case Long l -> String.format("Long value: %d (64-bit)", l);
        case String s when s.isBlank() -> "Empty string";
        case String s -> "String of length " + s.length();
        default -> obj.toString();
    };
}