Pattern matching for switch statements is a new feature introduced in Java 16 that allows for more concise and expressive switch statements. This feature enables developers to use pattern matching to test expressions against multiple patterns, making it easier to write cleaner and more readable code. In this blog article, we will discuss how to use pattern matching for switch statements and provide examples of its usage.

The basic syntax for a pattern matching switch statement is as follows:

switch (expression) {
	case pattern1 -> statement1;
    case pattern2 -> statement2;
    // ...     case patternN -> statementN;
    default -> statement; 
}

In this syntax, the expression is the value being tested, and each case represents a pattern to match against. The “->” symbol is used to separate the pattern from the statement that should be executed if the pattern matches. The “default” case is used to handle any values that do not match any of the specified patterns.

Patterns can include type patterns, which test whether an expression is an instance of a specific type, and “instanceof” patterns, which test whether an expression is an instance of a type and bind the expression to a variable. Here’s an example of a pattern matching switch statement that uses both type and “instanceof” patterns:

public String getMessage(Object obj) {
	return switch (obj) {
		case String s -> "The string is: " + s;
		case Integer i && i > 0 -> "The integer is positive: " + i;
		case Integer i && i < 0 -> "The integer is negative: " + i;         
		case Date d -> "The date is: " + d;
		default -> "Unknown object type";     
	}; 
}

In this example, the “getMessage” method takes an object as input and returns a string based on the type of the input object. The first case uses a type pattern to test whether the input object is a string and binds the expression to the variable “s”. The second and third cases use “instanceof” patterns to test whether the input object is an integer and whether it is positive or negative, respectively. The fourth case uses a type pattern to test whether the input object is a date. The “default” case is used to handle any input objects that do not match any of the specified patterns.

One of the benefits of pattern matching for switch statements is that it allows for more concise and readable code. Prior to this feature, developers often needed to use if-else statements or create separate methods to handle different cases, which could lead to more complex and verbose code. With pattern matching for switch statements, developers can more easily express their intentions and handle multiple cases in a single statement.

In conclusion, pattern matching for switch statements is a new feature in Java 16 that allows for more concise and expressive switch statements. By using type and “instanceof” patterns, developers can more easily handle multiple cases in a single statement, leading to cleaner and more readable code.