‘switch’ Statements in Java

Introduction

The switch statement in Java offers an elegant alternative to a long series of if-else conditions. It is especially useful when comparing a single variable against multiple possible values. This article will explore how the switch statement works, its syntax, and practical examples from the project file. By mastering the switch statement, you can make your code more readable and efficient, especially when dealing with multiple discrete values.

What is a ‘switch’ Statement?

The switch statement evaluates an expression and executes code blocks based on the result of that expression. Each possible result is matched against a case label, and the corresponding block of code is executed. If no case matches, the default block is executed if it is defined.

Syntax of ‘switch’


switch (expression) {
    case value1:
        // Code to execute if expression equals value1
        break;
    case value2:
        // Code to execute if expression equals value2
        break;
    // Add more cases as needed
    default:
        // Code to execute if no case matches
}

switch (expression) {

case value1:

// Code to execute if expression equals value1

break;

case value2:

// Code to execute if expression equals value2

break;

// Add more cases as needed

default:

// Code to execute if no case matches

}

expression: A variable or expression whose value is compared against each case.
value1, value2, etc.: Constants or literals that the expression is compared against.
The break statement exits the switch block. Without it, the program will continue to execute the subsequent cases (“fall-through”).

Why Use ‘switch’ Statements?

The switch statement is beneficial for scenarios where a single variable needs to be compared against multiple possible values. It is more readable and efficient than multiple else if statements for this purpose. Additionally, the switch statement supports byte, short, char, int, String, and enum types, making it versatile for various use cases.

Example: Using ‘switch’ Statements

Let’s explore an example that demonstrates how to use the switch statement with a String value and its practical application in Java.

Code Example: `Sample.java`


package org.studyeasy;

public class Sample {
    public static void main(String[] args) {
        String name = "Editor";

        switch (name.toLowerCase()) {
            case "author" -&gt; System.out.println("Chaand");
            case "team" -&gt; System.out.println("Team StudyEasy");
            case "editor" -&gt; System.out.println("Jack and Jill");
            default -&gt; System.out.println("Invalid entry");
        }
    }
}

package org.studyeasy;

public class Sample {

public static void main(String[] args) {

String name = "Editor";

switch (name.toLowerCase()) {

case "author" -> System.out.println("Chaand");

case "team" -> System.out.println("Team StudyEasy");

case "editor" -> System.out.println("Jack and Jill");

default -> System.out.println("Invalid entry");

}

Code Explanation

Variable Declaration:
- String name = "Editor";
- We declare a String variable name with the value "Editor".
Switch Statement:
- switch (name.toLowerCase()) converts the name variable to lowercase before evaluating it in the switch statement.
Matching Case:
- The case "editor": matches the lowercase value of name, which is "editor". The corresponding code block System.out.println("Jack and Jill"); is executed, printing Jack and Jill to the console.
Default Case:
- The default case is executed if none of the specified cases match the value of name. In this example, if the value of name were something other than "author", "team", or "editor", the message Invalid entry would be printed.

Output of the Code

Jack and Jill

1 2	Jack and Jill

Explanation of the Output

In this program, the variable name is initially set to "Editor". The switch statement evaluates the lowercase version of name (which is "editor"). It matches the third case, "editor", and prints the message Jack and Jill to the console. If the value of name had been something other than "author", "team", or "editor", the default case would have executed, printing Invalid entry.

Practical Use Cases for ‘switch’ Statements

Menu-Based Programs: Handling user input in command-line applications, such as a menu selection.
Enum-Based Decisions: Using enums in switch statements to handle various states or options in a program.
Event Handling: Handling different types of events based on a specific input or action.

Key Concepts to Remember

Each case must have a constant or literal value.
The default case is optional but recommended to handle unexpected values.
switch statements can use String, numeric types (byte, short, char, int), and enums.
The toLowerCase() method can be used to ensure case-insensitive comparisons when using switch with String values.

Conclusion

The switch statement in Java provides a clear and structured way to handle multiple conditions for a single expression. It is more efficient and readable than a chain of if-else statements, making it ideal for scenarios like menu selections or event handling. Understanding how to implement and optimize switch statements will improve the quality of your Java code.