ICSE Class 10 Computer Applications — 2024 Paper

Polygon is the class and the pictures are objects

Reason — In object-oriented programming (OOP), a class is a blueprint or template that defines the properties and behaviours (methods) of objects. An object is an instance of a class that holds specific data defined by the class.

In this case:

• Polygon represents the class because it defines the general structure, properties, and methods common to all polygons (e.g., sides, vertices, perimeter calculation).
• The pictures are specific examples or instances of polygons, such as triangles, parallelogram, or pentagons, making them objects created from the Polygon class.

b

Reason — In Java, when an int value is cast to char, it is converted based on the ASCII code. Since, 98 is the ASCII code of the letter b, hence value of ch is 'b'.

6

Reason — The method indexOf(char ch) in Java returns the index of the first occurrence of the specified character ch in the string. If the character is not found, it returns -1.

Consider the string:
"CONCENTRATION"

Let’s count the characters by their index (Java uses zero-based indexing):

C	O	N	C	E	N	T	R	A	T	I	O	N
0	1	2	3	4	5	6	7	8	9	10	11	12

The first occurrence of the character 'T' is at index 6.

Thus, the output of the statement "CONCENTRATION".indexOf('T') is 6.

private

Reason — In Java, access specifiers determine the visibility or accessibility of classes, methods, and variables. The three main access specifiers are:

1. public: Accessible from anywhere in the program.
2. protected: Accessible within the same package and by subclasses even if they are in different packages.
3. private: Accessible only within the same class.

private gives least accessibility as it provides the most restricted access.

13

Reason — The method compareTo(String str) in Java compares two strings lexicographically based on the ASCII values of characters. It returns:

0 if both strings are equal.
A positive value if the calling string comes after the argument string.
A negative value if the calling string comes before the argument string.

How It Works:
We compare "talent" and "genius" using their first differing characters:

• The ASCII value of 't' = 116
• The ASCII value of 'g' = 103

The difference is:
116 - 103 = 13

Since 't' comes after 'g', the result is 13.

\t

Reason — In Java, an escape sequence is a combination of characters starting with a backslash (\) followed by a specific character that performs a special operation.

Analysing the given options:

1. /n – Incorrect, should be \n (Backslash is required).
2. \t – Correct, it represents a tab.
3. /t – Incorrect, should be \t.
4. //n – Incorrect, this is not an escape sequence; // is used for comments in Java.

a

Reason — The && (Logical AND) operator in Java is used to combine two boolean expressions. It returns true only if both expressions are true. If either of the expressions is false, the entire condition becomes false.

The condition if (a > b && b > c) checks two expressions:

1. a > b – Checks if a is greater than b.
2. b > c – Checks if b is greater than c.

Since both conditions must be true (due to the && operator), the logical sequence becomes:
a > b > c

In this sequence:
a is the largest number because it is greater than both b and c.

11.0

Reason — The method Math.ceil(double value) in Java rounds up a decimal number to the next highest integer, regardless of the fractional part.

Breakdown of the Expression:

1. Math.ceil(5.4):
   5.4 is rounded up to 6.0.

2. Math.ceil(4.5):
   4.5 is rounded up to 5.0.

Adding the Results:
6.0 + 5.0 = 11.0

isLetterOrDigit(char)

Reason — In Java, the method Character.isLetterOrDigit(char ch) is used to check whether a given character ch is either a letter (A-Z or a-z) or a digit (0-9).

Analysing Other Options:

1. isDigit(char) – This method only checks if the character is a digit, not a letter.
2. isLetterOrDigit() – Incorrect because this method requires a character parameter.
3. isLETTERorDIGIT(char) – Java methods are case-sensitive, and method names follow camelCase. This method name does not exist.

java

Reason — In Java, source code files are saved with the .java extension. These files contain the Java program's source code, written in human-readable text format.

24

Reason — In Java, a character (char) takes 2 bytes because Java uses Unicode encoding.

Given:
Character Array: 4 rows and 3 columns
Total Elements = 4 × 3 = 12 characters

Memory Calculation:
Each character = 2 bytes
Total Memory = 12 × 2 = 24 bytes

double

Reason — The switch statement in Java supports specific data types for the case labels. However, double and float data types cannot be used.

Data Types supported in switch statement are:

1. int
2. char
3. String

a and b

Reason — An entry-controlled loop checks the loop condition before executing the loop's body. If the condition is false at the start, the loop's body will not execute even once.
for and while loops check the condition before running the loop's body. If the condition is false, the loop won't run. Therefore, they are entry controlled loops.
The body of the do-while loop executes at least once before checking the condition. Hence, it is an exit controlled loop.

Pure method

Reason — A pure method in Java is a method that:

1. Returns a value based only on its input arguments.
2. Does not modify any external variables or system state.
3. Does not change any class fields or input values.

In the context of reversing a number, a pure method accepts the number as input and returns its reversed form without altering any external state.

Yellow

Reason — In Java, a constructor must have the same name as the class. It initializes an object when it is created. Since the class name is Yellow, the constructor's name must be exactly Yellow, matching the class name including capitalization.

Call by reference

Reason — When an object is passed to a method:

1. The method receives a reference (memory address) to the original object.
2. Any changes made inside the method affect the original object.

fruit mango = new fruit();

Reason — In Java, creating an object follows the syntax:

ClassName objectName = new ClassName();

Where:

• ClassName: The name of the class.
• objectName: The name of the object.
• new: Allocates memory for the object.
• ClassName(): Calls the class's constructor.

Thus, fruit mango = new fruit(); correctly creates mango named object of fruit class.

Assertion and Reason both are false.

Reason — A static method can only access static variables and static methods directly because it belongs to the class, not any specific object. Hence, Assertion is false.
Both instance and static methods can access static variables. Hence, Reason is false.

6

Reason — The given Java code declares and initializes a String array color with three elements. The array elements are:

• color[0] = "Blue"
• color[1] = "Red"
• color[2] = "Violet"

The method length() returns the number of characters in the string "Violet".

Math.round(n)

Reason — In Java, Math.round(n) is the only method in the list that returns an integer when called with a floating-point number (float or double).

The Java expression for the given mathematical expression can be written as:

double result = Math.abs(a + b) / Math.sqrt(Math.pow(a, 2) + Math.pow(b, 2));

The given expression is evaluated as follows:

x += x++ * ++x % 2
x = x + (x++ * ++x % 2) (x = 4)
x = 4 + (4 * ++x % 2) (x = 5)
x = 4 + (4 * 6 % 2) (x = 6)
x = 4 + (24 % 2) (x = 6)
x = 4 + 0 (x = 6)
x = 4

Below is the for loop version of the provided do-while segment:

public class Main {
    public static void main(String[] args) {
        int x = 10, y = 20;

        for (; x <= 20; x++, y++) {
            // Body is empty because the increments are in the for loop header
        }

        System.out.println(x * y);
    }
}

20

The loop executes 0 times because the loop condition x>20 is false as value of x is 10.

100

Reason — The code converts the strings "45.50" and "54.50" into doubles using Double.parseDouble(), resulting in d1 = 45.5 and d2 = 54.5. Their sum is 100.0.
Casting 100.0 to an integer using (int) removes the decimal part, leaving x = 100.

(a) The order of the array is 4 x 3 as it has 4 rows and 3 columns.

(b) The value is evaluated as follows:

x[0][0] = 4
x[2][2] = 10

x[0][0]+x[2][2] = 4 + 10 = 14

Differences between boxing and unboxing are:

Boxing	Unboxing
It is the process of converting a primitive type to its corresponding wrapper class object.	It is the process of converting a wrapper class object back to its corresponding primitive type.
It occurs when assigning a primitive value to a wrapper object.	It occurs when assigning a wrapper object to a primitive variable.
Example: int num = 10; Integer obj = num;	Example: Integer obj = 20; int num = obj;

boolean x = a.compareTo(b); has the error.

Corrected statement is:

boolean x = (a.compareTo(b) == 0);

false

Explanation

The error occurs in this line:

boolean x = a.compareTo(b);

• The compareTo() method of the String class returns an int, not a boolean.
• The method compares two strings lexicographically and returns:
  • 0 if the strings are equal.
  • A positive value if the calling string is lexicographically greater.
  • A negative value if the calling string is lexicographically smaller.

Since an int cannot be assigned to a boolean variable, this causes a "incompatible types" error.

To fix the error, we can use a comparison to convert the int result into a boolean:

boolean x = (a.compareTo(b) == 0);  // True if strings are equal

This assigns true or false based on whether the two strings are equal.

Corrected Program:

void calculate() {
    String a = "KING", b = "KINGDOM";
    boolean x = (a.compareTo(b) == 0);  // Check if strings are equal
    System.out.println(x);
}

Output of the Program:

• "KING".compareTo("KINGDOM") compares the strings lexicographically.
• "KING" is lexicographically smaller than "KINGDOM".
• The result of compareTo() will be -3 (difference between the lengths of the two strings ⇒ 4 - 7 = -3).

Since a.compareTo(b) == 0 is false, the output will be:

false

(a) The concept of Constructor Overloading (Polymorphism) is depicted in the program.

(b) Output of the main() method:

10
30

Explanation:

Output of the program is explained below:

1. temp t = new temp();
   Calls the default constructor temp() → a = 10

2. temp x = new temp(30);
   Calls the parameterized constructor temp(int z) → a = 30

3. t.print();
   Prints value of a for t → 10

4. x.print();
   Prints value of a for x → 30

(a) java.lang

(b) import java.util.Scanner

import java.util.Scanner;

public class courier
{
    private String name;
    private double weight;
    private String address;
    private double bill;
    private char type;
    
    public void accept() {
        Scanner in = new Scanner(System.in);

        System.out.print("Enter customer's name: ");
        name = in.nextLine();
        
        System.out.print("Enter recipient's address: ");
        address = in.nextLine();

        System.out.print("Enter parcel weight (in Kgs): ");
        weight = in.nextDouble();

        System.out.println("Enter courier type");
        System.out.print("D (Domestic), I (International): ");
        type = in.next().charAt(0);
    }
    
    public void calculate() {
        if (weight <= 5) {
            bill = weight * 800;
        } else if (weight <= 10) {
            bill = (5 * 800) + ((weight - 5) * 700);
        } else {
            bill = (5 * 800) + (5 * 700) + ((weight - 10) * 500);
        }

        if (type == 'I') {
            bill += 1500;
        }
    }
    
    public void print() {
        System.out.println("Customer's Name: " + name);
        System.out.println("Parcel Weight: " + weight + " Kgs");
        System.out.println("Recipient's Address: " + address);
        System.out.println("Type of Courier: " + type);
        System.out.println("Bill Amount: Rs." + bill);
    }

    public static void main(String[] args) {
        courier obj = new courier();
        obj.accept();
        obj.calculate();
        obj.print();
    }
}

import java.util.Scanner;

public class KboatOverloadPerform
{
    double perform(double r, double h) {
        double l = Math.sqrt((r * r) + (h * h));
        double csa = Math.PI * r * l;
        return csa;
    }
    
    void perform(int r, int c) {
        for (int i = 1; i <= r; i++) {
            for (int j = 1; j <= c; j++) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
    
    void perform(int m, int n, char ch) {
        if (ch == 'Q') {
            int q = m / n;
            System.out.println("Quotient: " + q);
        } else if (ch == 'R') {
            int r = m % n;
            System.out.println("Remainder: " + r);
        } else {
            System.out.println("Invalid Character!");
        }
    }
    
    public static void main(String[] args) {
        KboatOverloadPerform mo = new KboatOverloadPerform();

        // Calculating CSA of a cone
        double csa = mo.perform(3.0, 4.0);
        System.out.println("Curved Surface Area of Cone: " + csa);

        // Generating pattern
        mo.perform(4, 5);

        // Printing quotient or remainder
        mo.perform(20, 6, 'Q');
        mo.perform(20, 6, 'R');
    }
}

import java.util.Scanner;

public class KboatEvenPal
{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        System.out.print("Enter a number: ");
        int num = in.nextInt();
        int org = num;
        int rev = 0;
        int sum = 0;
        
        while (num > 0) {
            int d = num % 10;
            rev = rev * 10 + d;
            sum += d;
            num /= 10;
        }
        

        if (org == rev && sum % 2 == 0) {
            System.out.println(org + " is an EvenPal number.");
        } else {
            System.out.println(org + " is not an EvenPal number.");
        }
    }
}

import java.util.Scanner;

public class KboatDiagonalDDA
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        int[][] arr = new int[4][4];
        
        System.out.println("Enter elements for 4x4 DDA:");
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                arr[i][j] = in.nextInt();
            }
        }
        
        int lSum = 0;
        int rSum = 0;
        
        for (int i = 0; i < 4; i++) {
            lSum += arr[i][i];
            rSum += arr[i][3 - i];
        }
        
        if (lSum == rSum) {
            System.out.println("The array is a DIAGONAL array.");
        } else {
            System.out.println("The array is NOT a DIAGONAL array.");
        }
    }
}

public class Pincode
{
    public static void main(String args[]) {
        int[] arr = {110061, 110001, 
                     110029, 110023, 
                     110055, 110006, 
                     110019, 110033};
                          
        for (int i = 0; i < 7; i++) 
        {
            int idx = i;
            for (int j = i + 1; j < 8; j++) 
            {
                if (arr[j] < arr[idx])
                    idx = j;
            }
            
            int t = arr[i];
            arr[i] = arr[idx];
            arr[idx] = t; 
        }
        
        System.out.println("Sorted Array:");
        for (int i = 0; i < 8; i++) 
        {
            System.out.print(arr[i] + " ");
        }

    }
}

import java.util.Scanner;

public class KboatValidateGmail
{
    public static void main(String args[]) 
    {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a Gmail ID: ");
        String gmailId = in.nextLine();
        int len = gmailId.length(); 

        if (gmailId.endsWith("@gmail.com")
        && gmailId.indexOf('@') == len - 10)
        {
            System.out.println(gmailId + " is a valid Gmail ID.");
        }
        else
        {
            System.out.println(gmailId + " is NOT a valid Gmail ID.");
        }
    }
}