Conditional Constructs in Java ICSE Class 10 Computer Applications

What Conditional Constructs in Java is about

Weightage: CISCE publishes no chapter weightage. Section A (40 marks) is compulsory: 1-mark MCQs and 2-mark short answers including output and error questions; in Section B you answer any four of six 15-mark programming questions written in Java.Source: CISCE ICSE Computer Applications (661) specimen paper structure for 2027

Key concepts

if and if-else

if statement: executes a statement or block only when the condition is true.
if (marks >= 40)
System.out.println("Pass");

if-else: executes one block when the condition is true and another when it is false.
if (n % 2 == 0)
System.out.println("Even");
else
System.out.println("Odd");

The condition must give a boolean (true/false). Without braces { }, only the next single statement belongs to the if or else; use braces when there is more than one statement. A semicolon right after if (...) ends the if: if (x > 0); makes the next statement run always.

Worked example

(2 marks) int x = -5; Give the output:
if (x > 0);
System.out.println("Positive");
System.out.println("Done");

Try it first, then show the solutionSolution

1. The semicolon after if (x > 0) is an empty statement; the if controls nothing - 1 mark.
2. Both println statements run regardless of x - 1 mark.

Answer: Positive
Done

if-else-if ladder and nested if

if-else-if ladder: tests several conditions in order; the first true condition's block runs and the rest are skipped; the final else (optional) runs if none is true. Ideal for slabs and grades:
if (m >= 90) grade = 'A';
else if (m >= 75) grade = 'B';
else if (m >= 60) grade = 'C';
else grade = 'D';

Nested if: an if inside another if, used when a second test depends on the first:
if (age >= 18)
{
if (hasID) System.out.println("Can vote");
else System.out.println("Bring ID");
}
else System.out.println("Too young");

An else always pairs with the nearest unmatched if above it, unless braces say otherwise.

Worked example

(2 marks) int x = 15; Give the output:
if (x > 10)
if (x > 20)
System.out.println("P");
else
System.out.println("Q");

Try it first, then show the solutionSolution

1. The else pairs with the nearest if, i.e. if (x > 20) - 1 mark.
2. x > 10 is true; x > 20 is false, so the else runs - 1 mark.

Answer: Q

switch-case, break, default and fall through

switch selects one of many cases by matching the value of an expression:
switch (choice)
{
case 1: System.out.println("Tea"); break;
case 2: System.out.println("Coffee"); break;
default: System.out.println("Invalid");
}

Rules: the switch expression may be int, char, String (and byte, short), but not double, float, long or boolean. Case labels must be constants and unique.
break ends the switch after a case runs.
default runs when no case matches (it is optional and may be anywhere).
Fall through: if a case has no break, execution continues into the following cases until a break or the end of the switch. It can be used on purpose to share code: case 'a': case 'e': case 'i': case 'o': case 'u': vowel++; break;

Worked example

(2 marks) int n = 2; Give the output:
switch (n)
{
case 1: System.out.print("A");
case 2: System.out.print("B");
case 3: System.out.print("C"); break;
default: System.out.print("D");
}

Try it first, then show the solutionSolution

1. n matches case 2: B is printed; there is no break, so it falls through - 1 mark.
2. case 3 prints C, then break stops; default is skipped - 1 mark.

Answer: BC

switch vs if-else-if, and System.exit(0)

Differences: (1) switch tests only equality with constant values; if can test any condition, including ranges (m >= 60). (2) switch works with int, char and String; if works with any boolean expression, including double comparisons. (3) switch is neater for menus with many fixed choices; if-else-if is needed for slabs and ranges.

System.exit(0) terminates the whole program at once (0 means normal termination). It is used in menu programs for an 'Exit' choice, or after a search is successful so that the 'not found' message is not printed.

Worked example

(2 marks) State two differences between switch-case and if-else-if.

Try it first, then show the solutionSolution

1. switch checks equality with constants only; if checks any condition, including ranges - 1 mark.
2. switch cannot use double or boolean expressions; if can - 1 mark.

Answer: (1) switch-case tests a value for equality with constant case labels, while if-else-if can test any condition such as ranges. (2) switch works only with int, char, String (and byte, short), while if-else-if works with any boolean condition, including double values.

Menu-driven programs

A menu-driven program shows a list of options, accepts the user's choice and uses switch to perform the chosen task, with default for an invalid choice.

import java.util.Scanner;
class AreaMenu
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.println("1. Circle 2. Square 3. Rectangle");
System.out.print("Choice: ");
int ch = sc.nextInt();
switch (ch)
{
case 1:
System.out.print("Radius: ");
double r = sc.nextDouble();
System.out.println("Area = " + (3.14 * r * r));
break;
case 2:
System.out.print("Side: ");
double s = sc.nextDouble();
System.out.println("Area = " + (s * s));
break;
case 3:
System.out.print("Length and breadth: ");
double l = sc.nextDouble();
double b = sc.nextDouble();
System.out.println("Area = " + (l * b));
break;
default:
System.out.println("Wrong choice");
}
}
}

Sample runs: choice 2, side 5 → Area = 25.0. Choice 7 → Wrong choice.

Worked example

(2 marks) In the menu program above, what is printed for choice 3 with length 4 and breadth 2.5? What if break after case 2 were removed and choice 2 was entered?

Try it first, then show the solutionSolution

1. Choice 3: 4 × 2.5 = 10.0, so Area = 10.0 - 1 mark.
2. Without break, after the square's area the program would fall into case 3 and ask for length and breadth too - 1 mark.

Answer: Area = 10.0. Without the break, choice 2 would print the square's area and then fall through into case 3, also asking for length and breadth.

Conditional Constructs in Java in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Switch Case, Fall Through and Menu-driven Programs

Conditional Constructs in Java: syntax and key facts

if-else syntax

if (condition) { … } else if (condition) { … } else { … }

else pairs with nearest unmatched if.

switch syntax

switch (expr) { case c1: …; break; case c2: …; break; default: …; }

expr: int, char, String, byte, short.

Slab formula

charge = (full lower slabs) + (units − slab start) × rate

e.g. 350 units: 100 × 2 + 200 × 3 + 50 × 5.

Exit

System.exit(0);

Ends the program immediately.

How the board asks Conditional Constructs in Java

The question patterns to expect, and the method that works for each.

Tricks to remember Conditional Constructs in Java

Short memory aids. Say each one aloud once, then use it on a question the same day.

• No break, keep falling

  Without break, switch keeps falling into the next case like water down steps.

  Use it when: Fall-through outputs.

• Switch says I-C-S

  Switch accepts Int, Char, String (and byte, short) - never double or boolean.

  Use it when: Switch data type MCQs.

Conditional Constructs in Java: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section B style)

Read the situation, then answer every part. In the board paper this is a 10-mark question split into 2 + 3 + 5 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Conditional Constructs in Java

The slips examiners see most often, and what to write instead.

• ✗Mistake: Wrong slab calculation or relational operator

  The 2024 examiners reported wrong slab calculations and relational operator syntax in the courier program; in 2025 candidates did not use the slab method for cloud storage.

  ✓Do this: Charge each slab at its own rate and add the full lower slabs; check <= at 'up to' boundaries.

  Usually costs: 3 to 6 marks of 15.

• ✗Mistake: Answering 'wrong expression' for a condition given in words

  In 2024 candidates treated if (a>b&&b>c) as a Java statement to judge rather than a logical condition.

  ✓Do this: Read what the condition means: a > b > c.

  Usually costs: 1 mark.

• ✗Mistake: Forgetting break

  Missing break causes fall through and extra output.

  ✓Do this: End every case with break unless fall through is intended.

  Usually costs: 1 to 2 marks.

• ✗Mistake: Using double in switch

  The 2024 MCQ tested this.

  ✓Do this: switch: int, char, String, byte, short only.

  Usually costs: 1 mark.

Practice questions on Conditional Constructs in Java

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   Which statement terminates a program?
   (a) break
   (b) continue
   (c) System.exit(0)
   (d) return 0

   Hint

   Whole program.

   Answer

   (c) System.exit(0)

2. Q2 · 1 mark · MCQBoard level

   In a switch, the block that runs when no case matches is:
   (a) else
   (b) default
   (c) break
   (d) case 0

   Hint

   Fallback.

   Answer

   (b) default

3. Q3 · 2 marks · Very short answerHarder board level

   Give the output: char ch = 'b'; switch (ch) { case 'a': System.out.print(1); case 'b': System.out.print(2); case 'c': System.out.print(3); default: System.out.print(4); }

   Hint

   No breaks anywhere.

   Answer

   234

4. Q4 · 2 marks · Very short answerBoard level

   Rewrite using if-else: res = (n % 3 == 0) ? "Multiple" : "Not multiple";

   Hint

   Ternary to if.

   Answer

   if (n % 3 == 0)
   res = "Multiple";
   else
   res = "Not multiple";

5. Q5 · 2 marks · Very short answerHarder board level

   Find the error: if (x = 5) System.out.println("Five");

   Hint

   Assignment vs comparison.

   Answer

   x = 5 is an assignment giving an int, but if needs a boolean, so it is a compile-time error. Correct: if (x == 5)

6. Q6 · 2 marks · Short answerHarder board level

   int a = 10, b = 20; Give the output:
   if (a > b)
   System.out.println("X");
   else
   System.out.println("Y");
   System.out.println("Z");

   Hint

   Only one statement in else.

   Answer

   Y
   Z (Z is outside the if-else and always prints)

7. Q7 · 15 marks · Long answerBoard level

   Write a program to accept a number and print whether it is positive, negative or zero, and if positive whether it is even or odd.

   Hint

   Nested if inside the positive branch.

   Answer

   import java.util.Scanner;
   class Check
   {
   public static void main(String args[])
   {
   Scanner sc = new Scanner(System.in);
   System.out.print("Number: ");
   int n = sc.nextInt();
   if (n > 0)
   {
   System.out.println("Positive");
   if (n % 2 == 0)
   System.out.println("Even");
   else
   System.out.println("Odd");
   }
   else if (n < 0)
   System.out.println("Negative");
   else
   System.out.println("Zero");
   }
   }
   Sample runs: 7 → Positive, Odd; -4 → Negative; 0 → Zero.

8. Q8 · 15 marks · Long answerHOTS / competency

   Suppose a shop gives a 5% discount on bills up to ₹2,000, 10% on bills above ₹2,000 up to ₹5,000, and 15% above ₹5,000. Write a program to accept the bill amount and print the discount rate and the net amount. Show the output for bills of ₹5,000 and ₹6,000.

   Hint

   Boundary 5,000 is in the 10% slab.

   Answer

   import java.util.Scanner;
   class Discount
   {
   public static void main(String args[])
   {
   Scanner sc = new Scanner(System.in);
   System.out.print("Bill amount: ");
   double b = sc.nextDouble();
   int d;
   if (b <= 2000)
   d = 5;
   else if (b <= 5000)
   d = 10;
   else
   d = 15;
   double net = b - b * d / 100.0;
   System.out.println("Discount: " + d + "%");
   System.out.println("Net amount = " + net);
   }
   }
   For 5000: Discount: 10% and Net amount = 4500.0 (5000 − 500). For 6000: Discount: 15% and Net amount = 5100.0 (6000 − 900).

9. Q9 · 2 marks · Short answerHOTS / competency

   Why is switch not suitable for checking marks in ranges such as 60 to 74?

   Hint

   Equality only.

   Answer

   switch compares the value only for equality with constant case labels; it cannot test a range, so you would need a separate case for every mark. An if-else-if ladder with m >= 60 && m < 75 is suitable.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Does switch accept String?Show answer

   Yes.

2. 2.What does break do in switch?Show answer

   Exits the switch, preventing fall through.

3. 3.Which if does an else pair with?Show answer

   The nearest unmatched if above it.

4. 4.What does System.exit(0) do?Show answer

   Terminates the program normally.

5. 5.Can switch test a range?Show answer

   No; only equality with constants.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐if / if-else / if-else-if / nested if.
• ☐switch: int, char, String, byte, short; constant unique cases.
• ☐No break → fall through; default → no match.
• ☐Slabs: if-else-if with <= boundaries.
• ☐System.exit(0) ends the program.

Conditional Constructs in Java: frequently asked questions