From Simple to Expressive: Java Switch Evolution: Java 13 and Beyond

Remember the days of clunky switch statements with endless breaks? Java has evolved, offering sleek switch expressions with magic like yield and multi-case matching! This introduction will show you how to wield these new features to write cleaner, more expressive code

Here are some more Java Switch Expression examples showcasing different features:

1. Multi-case Matching(Java 14)

int days = switch (month) {
        case 1, 3, 5, 7, 8, 10, 12 -> 31;
        case 4, 6, 9 -> 30;
        case 2 -> 28;
        default -> 0;
};

In prior java versions we would do the same using this verbose code :

int days = 0;
switch (month) {
    case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12:
        days = 31;
        break;
    case 4:
    case 6:
    case 9:
        days = 30;
        break;
    case 2:
        days = 28;
        break;
    default:
        throw new IllegalArgumentException("Invalid month");
}

Explanation: You can match multiple constants in a single case clause by separating them with commas.

2. Yield (Java 13)

int value = switch (greeting) {
    case "hi" -> {
        System.out.println("I am not just yielding!");
        yield 1;
    }
    case "hello" -> {
        System.out.println("Me too.");
        yield 2;
    }
    default -> {
        System.out.println("OK");
        yield -1;
    }
};

What’s the difference to a default return?

A return statement returns control to the invoker of a method or constructor  while a yield statement transfers control by causing an enclosing switch expression to produce a specified value.

3. Pattern Matching for instanceOf (Java 17)

It will match the instance of the object being passed

Object obj = 42;
String message = switch (obj) {
    case Integer i -> "Number: " + i;
    case String s -> "String: " + s;
    default -> "Unknown type";
};
System.out.println(message); // Output: "Number: 42"

Another example :

private static void printType(Object input){                                                 
    switch (input) {                                                                         
        case Integer i && i > 10 -> System.out.println("Integer is greater than 10");        
        case String s && !s.isEmpty()-> System.out.println("String!");                       
        default -> System.out.println("Invalid Input");                                      
    }                                                                                        
}      

4. Switch expressions

A big improvement is that switch statements can be used to return a value and therefore can be used as expression. You can even return it

System.out.println(switch (x) {
    case 1 -> "One";
    case 2 -> "Two";
    default -> "Unknown";
});