Leer Enums in Switch Statements | Enums in Control Flow and Collections

Switch statements in Java provide a concise way to branch logic based on the value of a variable. When you use enums in switch statements, you gain several advantages that make your code more readable and less error-prone. Enums are ideal for switch statements because they provide a finite set of known constants. This allows you to clearly express all possible cases in your logic, and the compiler can even warn you if you forget to handle an enum constant. When you switch on an enum, each case can directly reference an enum constant without needing to compare strings or integers, which reduces the risk of mistakes and makes your intent obvious to anyone reading the code.

Main.java


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package com.example;

enum Season {
    SPRING, SUMMER, FALL, WINTER
}

public class Main {
    public static void main(String[] args) {
        Season current = Season.SUMMER;
        switch (current) {
            case SPRING:
                System.out.println("Time for flowers to bloom!");
                break;
            case SUMMER:
                System.out.println("Let's go to the beach!");
                break;
            case FALL:
                System.out.println("Leaves are falling.");
                break;
            case WINTER:
                System.out.println("Snow is coming.");
                break;
        }
    }
}

When working with switch statements and enums, it is important to understand how the control flow operates. Each case in the switch should correspond to an enum constant. If you forget to handle a particular constant, the compiler may warn you, especially if you do not include a default case. The default case serves as a catch-all for any values not explicitly handled by the other case statements. However, because enums define a fixed set of constants, a well-written switch on an enum will typically handle every possible value explicitly. Fall-through, where control passes from one case to the next without a break, is possible but usually discouraged with enums, since each constant should map to its own logic. Including a default case can help future-proof your code if new enum constants are added later.

Main.java


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package com.example;

enum Status {
    NEW, IN_PROGRESS, COMPLETED
}

public class Main {
    public static void main(String[] args) {
        Status status = getStatusFromExternalSource();
        switch (status) {
            case NEW:
                System.out.println("Status is new.");
                break;
            case IN_PROGRESS:
                System.out.println("Work is in progress.");
                break;
            case COMPLETED:
                System.out.println("Task completed.");
                break;
            default:
                System.out.println("Unknown status!");
                break;
        }
    }

    private static Status getStatusFromExternalSource() {
        // Simulate receiving a value, could be unknown in future versions
        return Status.NEW;
    }
}

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Main.java


              1234567891011121314151617181920212223242526
            
package com.example;

enum Season {
    SPRING, SUMMER, FALL, WINTER
}

public class Main {
    public static void main(String[] args) {
        Season current = Season.SUMMER;
        switch (current) {
            case SPRING:
                System.out.println("Time for flowers to bloom!");
                break;
            case SUMMER:
                System.out.println("Let's go to the beach!");
                break;
            case FALL:
                System.out.println("Leaves are falling.");
                break;
            case WINTER:
                System.out.println("Snow is coming.");
                break;
        }
    }
}

Main.java


              12345678910111213141516171819202122232425262728293031
            
package com.example;

enum Status {
    NEW, IN_PROGRESS, COMPLETED
}

public class Main {
    public static void main(String[] args) {
        Status status = getStatusFromExternalSource();
        switch (status) {
            case NEW:
                System.out.println("Status is new.");
                break;
            case IN_PROGRESS:
                System.out.println("Work is in progress.");
                break;
            case COMPLETED:
                System.out.println("Task completed.");
                break;
            default:
                System.out.println("Unknown status!");
                break;
        }
    }

    private static Status getStatusFromExternalSource() {
        // Simulate receiving a value, could be unknown in future versions
        return Status.NEW;
    }
}

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Sectie 3. Hoofdstuk 1

Enums in Switch Statements

1. What is the benefit of using enums in switch statements?

2. What happens if you omit a case for an enum constant in a switch statement?

3. Can you use enums in switch statements in all versions of Java?

Enums in Switch Statements

1. What is the benefit of using enums in switch statements?

2. What happens if you omit a case for an enum constant in a switch statement?

3. Can you use enums in switch statements in all versions of Java?