Why conditional statements are needed in Java - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Adult" if age is 18 or more.

Java

int age = 20;
if (age [1] 18) {
    System.out.println("Adult");
}

Drag options to blanks, or click blank then click option'

A>=

B==

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>=' causes the condition to be false for age 20.

Using '==' only checks if age is exactly 18, not more.

The condition age >= 18 checks if age is 18 or more, so it prints "Adult" correctly.

2fill in blank

medium

Complete the code to print "Even" if number is divisible by 2.

Java

int number = 10;
if (number [1] 2 == 0) {
    System.out.println("Even");
}

Drag options to blanks, or click blank then click option'

A+

B/

C%

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '/' divides the number but does not check remainder.

Using '*' or '+' does not help check divisibility.

The modulus operator % gives the remainder. If number % 2 == 0, the number is even.

3fill in blank

hard

Fix the error in the condition to check if score is less than 50.

Java

int score = 45;
if (score [1] 50) {
    System.out.println("Fail");
}

Drag options to blanks, or click blank then click option'

A<

B>

C==

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' checks if score is greater than 50, which is wrong here.

Using '==' checks equality, not less than.

The condition should be score < 50 to check if score is less than 50.

4fill in blank

hard

Fill both blanks to print "Teenager" if age is between 13 and 19 inclusive.

Java

int age = 15;
if (age [1] 13 && age [2] 19) {
    System.out.println("Teenager");
}

Drag options to blanks, or click blank then click option'

A>=

B<

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '<=' excludes age 19.

Using '>' instead of '>=' excludes age 13.

The condition age >= 13 && age <= 19 checks if age is between 13 and 19 inclusive.

5fill in blank

hard

Fill all three blanks to print "Eligible" if salary is above 3000, age is at least 18, and experience is more than 2 years.

Java

int salary = 3500;
int age = 25;
int experience = 3;
if (salary [1] 3000 && age [2] 18 && experience [3] 2) {
    System.out.println("Eligible");
}

Drag options to blanks, or click blank then click option'

A>=

B>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' for salary includes 3000, but requirement is above 3000.

Using '<' for experience is incorrect here.

The conditions are: salary > 3000, age >= 18, and experience > 2 to print "Eligible".

Practice

1. Why do we need conditional statements like if in Java programs?

easy

A. To make decisions and run different code based on conditions

B. To repeat the same code multiple times

C. To store multiple values in a list

D. To define a new class or method

Solution

1. Step 1: Understand the purpose of conditional statements

   Conditional statements allow the program to choose different paths based on true or false conditions.

2. Step 2: Compare with other options

   Loops repeat code, lists store values, and classes define structure, but only conditionals make decisions.

3. Final Answer:

   To make decisions and run different code based on conditions -> Option A

4. Quick Check:

   Conditional statements = decision making [OK]

Hint: Conditionals = choosing between options [OK]

Common Mistakes:

• Confusing conditionals with loops
• Thinking conditionals store data
• Mixing conditionals with class definitions

2. Which of the following is the correct syntax to start a conditional statement in Java?

easy

A. switch condition { }

B. for (condition) { }

C. while condition { }

D. if (condition) { }

Solution

1. Step 1: Identify the syntax for an if statement

   The correct syntax uses the keyword if followed by parentheses around the condition and curly braces for the code block.

2. Step 2: Check other options

   for and while are loops, and switch has a different syntax with cases.

3. Final Answer:

   if (condition) { } -> Option D

4. Quick Check:

   if statement syntax = if (condition) { } [OK]

Hint: If starts with 'if' and parentheses [OK]

Common Mistakes:

• Using loop keywords instead of if
• Missing parentheses around condition
• Using switch syntax for if

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

int x = 10;
if (x > 5) {
  System.out.println("Greater");
} else {
  System.out.println("Smaller");
}

medium

A. 10

B. Greater

C. Smaller

D. No output

Solution

1. Step 1: Evaluate the condition x > 5

   Since x is 10, which is greater than 5, the condition is true.

2. Step 2: Determine which block runs

   The if block runs and prints "Greater"; the else block is skipped.

3. Final Answer:

   Greater -> Option B

4. Quick Check:

   10 > 5 is true, so prints "Greater" [OK]

Hint: Check if condition is true or false [OK]

Common Mistakes:

• Choosing else output when condition is true
• Confusing printed value with variable value
• Ignoring the else block

4. Find the error in this Java code snippet:

int num = 7;
if num > 5 {
  System.out.println("Yes");
} else {
  System.out.println("No");
}

medium

A. Missing parentheses around the condition in if statement

B. Missing semicolon after if statement

C. Incorrect use of else keyword

D. Variable num is not declared

Solution

1. Step 1: Check the if statement syntax

   The condition in an if statement must be inside parentheses, but here it is missing.

2. Step 2: Verify other parts

   Semicolons are not needed after if conditions, else is correctly used, and variable num is declared.

3. Final Answer:

   Missing parentheses around the condition in if statement -> Option A

4. Quick Check:

   if condition needs parentheses [OK]

Hint: If condition always inside ( ) [OK]

Common Mistakes:

• Forgetting parentheses in if
• Adding semicolon after if condition
• Thinking else needs parentheses

5. You want to write a Java program that prints "Adult" if age is 18 or more, "Teen" if age is between 13 and 17, and "Child" otherwise. Which conditional structure correctly implements this?

hard

A. if (age > 18) { System.out.println("Adult"); } else if (age > 13) { System.out.println("Teen"); } else { System.out.println("Child"); }

B. if (age >= 18) { System.out.println("Adult"); } else if (age > 13 && age < 18) { System.out.println("Teen"); } else { System.out.println("Child"); }

C. if (age >= 18) { System.out.println("Adult"); } else if (age >= 13) { System.out.println("Teen"); } else { System.out.println("Child"); }

D. if (age > 18) { System.out.println("Adult"); } else if (age >= 13 && age <= 17) { System.out.println("Teen"); } else { System.out.println("Child"); }

Solution

1. Step 1: Check the age ranges for each category

   Adult is 18 or more, Teen is 13 to 17 inclusive, Child is below 13.

2. Step 2: Analyze each option's conditions

   if (age >= 18) { System.out.println("Adult"); } else if (age >= 13) { System.out.println("Teen"); } else { System.out.println("Child"); } uses >= 18 for Adult, >= 13 for Teen (which covers 13 to 17), else Child. This matches the requirement exactly.

3. Final Answer:

   if (age >= 18) { System.out.println("Adult"); } else if (age >= 13) { System.out.println("Teen"); } else { System.out.println("Child"); } -> Option C

4. Quick Check:

   Correct age ranges with if-else if-else [OK]

Hint: Check boundary conditions carefully [OK]

Common Mistakes:

• Using > instead of >= causing wrong category
• Overlapping or missing age ranges
• Incorrect else if conditions order