🚀 Day 23 of My Automation Journey – Switch Case Tricky Questions 🔥

Today I explored advanced and tricky scenarios in Java Switch Case.

At first glance, switch-case looks simple… but when you remove break, use default, or mix data types — things get very tricky 😲

This is also a favorite topic in interviews.

🔹 Before Java 8 – Traditional Switch

int x = 2;

switch(x) {
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
        break;
    case 3:
        System.out.println("Three");
        break;
    default:
        System.out.println("Default");
}

📤 Output

Two

✔ break stops execution
✔ Only matching case executes

🔹 After Java 8+ (Arrow Syntax)

int x = 2;

switch(x) {
    case 1 -> System.out.println("Hi");
    case 2 -> System.out.println("Welcome");
    default -> System.out.println("Hello");
}

📤 Output

Welcome

✔ No need for break
✔ No fall-through

🔹 Switch Expression (Java 12+)

int x = 2;

int result = switch(x) {
    case 1 -> 10;
    case 2 -> 20;
    default -> 0;
};

System.out.println(result);

📤 Output

20

🔹 Java 17+ Pattern Matching

Object obj = "Hello";

switch(obj) {
    case String s -> System.out.println(s.length());
    case Integer i -> System.out.println(i * 2);
    default -> System.out.println("Other");
}

📤 Output

5

🔥 Tricky Questions
🔍 1. Missing break (Fall-through)

int x = 2;

switch(x) {
    case 1:
        System.out.println("One");
    case 2:
        System.out.println("Two");
    case 3:
        System.out.println("Three");
    default:
        System.out.println("Default");
}

📤 Output

Two
Three

Default
✅ Explanation

✔ Starts from matching case → case 2
✔ No break → continues executing all below

🔍 2. char vs ASCII

char ch = 'A';

switch(ch) {
    case 65:
        System.out.println("ASCII 65");
        break;
    case 'A':
        System.out.println("Character A");
}

📤 Output

ASCII 65

✅ Explanation

✔ 'A' = 65 internally
✔ First matching case executes

🔍 3. Expression inside switch

int x = 10;

switch(x / 2) {
    case 5:
        System.out.println("Five");
        break;
    case 10:
        System.out.println("Ten");
}

📤 Output

Five

✅ Explanation

✔ x/2 = 5 → matches case 5

🔍 4. Multiple case labels

int x = 2;

switch(x) {
    case 1:
    case 2:
        System.out.println("One or Two");
        break;
    case 3:
        System.out.println("Three");
}

📤 Output

One or Two

✅ Explanation

✔ Multiple cases share same block

🔍 5. Missing break again

int x = 2;

switch(x) {
    case 1:
    case 2:
        System.out.println("One or Two");
    case 3:
        System.out.println("Three");
}

📤 Output

One or Two
Three

✅ Explanation

✔ Fall-through again due to missing break

🔍 6. Fall-through chain

int x = 3;

switch(x) {
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
    case 3:
        System.out.println("Three");
    case 4:
        System.out.println("Four");
        break;
}

📤 Output

Three
Four

✅ Explanation

✔ Starts at case 3
✔ No break → continues

🔍 7. Default in middle

int x = 2;

switch(x) {
    default:
        System.out.println("Default");
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
}

📤 Output

Two

✅ Explanation

✔ Matching case runs directly
✔ Default is ignored

🔍 8. Default fall-through

int x = 5;

switch(x) {
    case 1:
        System.out.println("One");
    default:
        System.out.println("Default");
    case 5:
        System.out.println("Five");
}

📤 Output

Default
Five

✅ Explanation

✔ No match → default executes
✔ Then continues to case 5

🔍 9. final variable in case

final int a = 1;
int b = 2;

switch(b) {
    case a:
        System.out.println("A");
        break;
    case a + 1:
        System.out.println("A+1");
}

📤 Output

A+1

✅ Explanation

✔ final makes it constant → allowed in case

🔍 10. String fall-through

String s = "Java";

switch(s) {
    case "Java":
        System.out.println("Java");
    case "JAVA":
        System.out.println("JAVA");
        break;
}

📤 Output

Java
JAVA

✅ Explanation

✔ Missing break → fall-through

🔍 11. null in switch

String s = null;

switch(s) {
    case "Hi":
        System.out.println("Hi");
        break;
    default:
        System.out.println("Default");
}

📤 Result

NullPointerException

✅ Explanation

✔ switch does NOT accept null

🔍 12. Duplicate case

int x = 1;

switch(x) {
    case 1:
        System.out.println("One");
        break;
    case 1:
        System.out.println("Duplicate");
}

📤 Result

Compile Time Error

✅ Explanation

✔ Duplicate case not allowed

🔍 13. Duplicate constant

final int a = 2;

switch(2) {
    case a:
        System.out.println("A");
        break;
    case 2:
        System.out.println("Two");
}

📤 Result

Compile Time Error

✅ Explanation

✔ Both represent same value → duplicate

🔍 14. Nested switch

int x = 1;

switch(x) {
    case 1:
        switch(x + 1) {
            case 2:
                System.out.println("Inner Two");
        }
    case 2:
        System.out.println("Outer Two");
}

📤 Output

Inner Two
Outer Two

✅ Explanation

✔ Inner switch executes
✔ No break → outer continues

🧠 Key Takeaways

✔ Missing break = fall-through
✔ default can be anywhere
✔ final variables allowed in case
✔ Duplicate case = compile error
✔ null not allowed
✔ Arrow syntax avoids fall-through

🏁 Conclusion

Today I learned how small mistakes in switch-case can lead to unexpected outputs.

These tricky questions are extremely helpful for:

✔ Java interviews
✔ Debugging code
✔ Writing clean logic in automation

Step by step, I’m strengthening my Java fundamentals for Selenium Automation 🚀

🤖 A Small Note

I used ChatGPT to help structure and refine this blog while ensuring the concepts remain aligned with my trainer’s explanations.