Switch vs if comparison in Java - Hands-On Comparison

Switch vs if comparison

📖 Scenario: Imagine you are building a simple program that tells the day of the week based on a number. You want to see how to use both switch and if statements to do this.

🎯 Goal: You will create a program that uses both switch and if to print the day name for a given number from 1 to 7.

📋 What You'll Learn

Create an integer variable called dayNumber with a value from 1 to 7

Create a switch statement that prints the day name for dayNumber

Create an if-else statement that prints the day name for dayNumber

Print the results of both switch and if-else statements

💡 Why This Matters

🌍 Real World

Programs often need to choose actions based on a value, like days of the week, menu options, or commands.

💼 Career

Understanding <code>switch</code> and <code>if-else</code> helps you write clear and efficient code for decision making in many software jobs.

1

Create the dayNumber variable

Create an integer variable called dayNumber and set it to 3.

Java

// Your code here

Hint

Use int dayNumber = 3; inside the main method.

2

Add a switch statement for dayNumber

Add a switch statement using dayNumber that prints the day name for numbers 1 to 7. Use System.out.println inside each case. For example, case 1 prints "Monday". Include a default case that prints "Invalid day".

Java

public class Main {
    public static void main(String[] args) {
        int dayNumber = 3;
        // Add switch statement here
    }
}

Hint

Use switch (dayNumber) { case 1: ... } and print the day names with System.out.println.

3

Add an if-else statement for dayNumber

Add an if-else statement using dayNumber that prints the day name for numbers 1 to 7. Use System.out.println inside each condition. For example, if dayNumber == 1, print "Monday". Include an else that prints "Invalid day".

Java

public class Main {
    public static void main(String[] args) {
        int dayNumber = 3;
        switch (dayNumber) {
            // switch cases here
        }
        // Add if-else statement here
    }
}

Hint

Use if (dayNumber == 1) { ... } else if (...) { ... } else { ... } and print day names.

4

Print the results of both switch and if-else

Run the program and observe the output. The program should print the day name twice: once from the switch statement and once from the if-else statement. The output should be exactly two lines with the day name "Wednesday".

Java

public class Main {
    public static void main(String[] args) {
        int dayNumber = 3;
        switch (dayNumber) {
            // switch cases here
        }
        if (dayNumber == 1) {
            // if-else here
        }
        // Run and observe output
    }
}

Hint

Run the program. It should print "Wednesday" two times, once from switch and once from if-else.

Practice

1. Which statement best describes when to use switch instead of if in Java?

easy

A. switch is best for checking many fixed values of a single variable.

B. switch can handle complex conditions like ranges easily.

C. if is only for checking equality, not ranges.

D. if cannot be used with multiple conditions.

Solution

1. Step 1: Understand switch usage

   switch works well when you have one variable and many fixed values to compare against.

2. Step 2: Compare with if

   if can handle any condition, including ranges and complex expressions, but switch is simpler for fixed values.

3. Final Answer:

   switch is best for checking many fixed values of a single variable. -> Option A

4. Quick Check:

   Use switch for fixed values = B [OK]

Hint: Use switch for fixed values, if for ranges or complex checks [OK]

Common Mistakes:

• Thinking switch can handle ranges
• Believing if is only for equality
• Assuming switch works with multiple variables
• Confusing switch with if-else chains

2. Which of the following is the correct syntax for a switch statement in Java?

easy

A. switch (variable) { case 1: doSomething(); break; default: doDefault(); }

B. switch variable { case 1: doSomething(); break; default: doDefault(); }

C. switch (variable) do { case 1: doSomething(); break; default: doDefault(); }

D. switch (variable) { case 1 doSomething(); break; default doDefault(); }

Solution

1. Step 1: Check switch syntax structure

   The correct syntax requires parentheses around the variable and braces enclosing cases.

2. Step 2: Verify case and break usage

   Each case ends with a colon and usually a break statement to prevent fall-through.

3. Final Answer:

   switch (variable) { case 1: doSomething(); break; default: doDefault(); } -> Option A

4. Quick Check:

   Correct switch syntax uses parentheses and colons = A [OK]

Hint: Remember switch needs parentheses and colons for cases [OK]

Common Mistakes:

• Omitting parentheses around variable
• Using braces instead of colons after case
• Missing break statements causing fall-through
• Incorrect placement of default case

3. What will be the output of the following Java code?

int day = 3;
switch(day) {
  case 1: System.out.println("Monday"); break;
  case 2: System.out.println("Tuesday"); break;
  case 3: System.out.println("Wednesday"); break;
  default: System.out.println("Invalid day");
}

medium

A. Monday

B. Tuesday

C. Invalid day

D. Wednesday

Solution

1. Step 1: Identify the value of day

   The variable day is set to 3.

2. Step 2: Match day with switch cases

   The case for 3 prints "Wednesday" and then breaks, so no other cases run.

3. Final Answer:

   Wednesday -> Option D

4. Quick Check:

   day=3 matches case 3 = C [OK]

Hint: Match variable value to case label, then print [OK]

Common Mistakes:

• Forgetting break causes fall-through
• Choosing default instead of matching case
• Confusing case numbers
• Assuming if-else output instead of switch

4. Identify the error in this Java code snippet:

int score = 85;
switch(score) {
  case score >= 90: System.out.println("A grade"); break;
  case score >= 80: System.out.println("B grade"); break;
  default: System.out.println("Fail");
}

medium

A. Missing break statements after cases.

B. Cannot use relational expressions in case labels.

C. Switch variable must be a String, not int.

D. Default case must be last.

Solution

1. Step 1: Understand switch case label restrictions

   Case labels must be constant values, not expressions like 'score >= 90'.

2. Step 2: Identify why relational expressions cause error

   Relational expressions are evaluated at runtime and cannot be used as case labels in switch.

3. Final Answer:

   Cannot use relational expressions in case labels. -> Option B

4. Quick Check:

   Case labels must be constants = A [OK]

Hint: Case labels must be constants, not conditions [OK]

Common Mistakes:

• Trying to use ranges in switch cases
• Forgetting case labels must be constant
• Assuming switch supports boolean expressions
• Misplacing default case

5. You want to print a message based on an integer score: "Excellent" if score >= 90, "Good" if score >= 75, "Average" if score >= 50, and "Poor" otherwise. Which approach is best in Java?

hard

A. Use a switch statement with case labels for each range.

B. Use a switch with string values for score.

C. Use nested if-else statements to check ranges.

D. Use a switch with boolean expressions in cases.

Solution

1. Step 1: Analyze the conditions

   The conditions involve ranges (score >= 90, >= 75, etc.) which cannot be directly used in switch cases.

2. Step 2: Choose the suitable control structure

   if-else statements can handle ranges and complex conditions easily, unlike switch.

3. Final Answer:

   Use nested if-else statements to check ranges. -> Option C

4. Quick Check:

   Ranges need if-else, not switch = D [OK]

Hint: Use if-else for ranges, switch only for fixed values [OK]

Common Mistakes:

• Trying to use switch for range conditions
• Using boolean expressions in switch cases
• Assuming switch works with strings for numbers
• Ignoring else for default case