9th final pratice


  • 🌟 JAVA QUICK REVISION – FULL EXAM NOTE 🌟

    (Read Carefully – High Scoring Concepts)

    🔹 1. Encapsulation

    Encapsulation means wrapping data (variables) and methods (functions) together into a single unit called a class.
    It is achieved by:

    • Declaring variables as private

    • Providing access through public getter and setter methods

    Example:

    class Student {
    private int marks;

    public void setMarks(int m) {
        marks = m;
    }

    public int getMarks() {
        return marks;
    }
}

    🔹 2. Comparison Operator → ==

    • Used to compare two values.

    • Returns true or false.

    Example:

    if (a == b)

    🔹 3. Loop That Runs At Least Once → do-while

    • Condition is checked after execution.

    • Executes minimum one time even if condition is false.

    Example:

    do {
    System.out.println("Hello");
} while(condition);

    🔹 4. Constant Variable Keyword → final

    • Once assigned, value cannot be changed.

    final int x = 10;

    🔹 5. Math.sqrt(16) → 4

    • Math.sqrt() returns square root.

    System.out.println(Math.sqrt(16)); // 4.0

    🔹 6. Logical AND → &&

    • Returns true only if both conditions are true.

    Example:

    if (a > 5 && b < 10)

    🔹 7. Best Loop When Iterations Are Known → for

    • Used when number of repetitions is fixed.

    Example:

    for(int i = 1; i <= 5; i++)

    🔹 8. Compile-Time Error → Syntax Error

    • Occurs when grammar rules of Java are violated.

    • Found during compilation.

    Example:

    System.out.println("Hello")   // Missing ;

    🔹 9. Maximum of Two Numbers → Math.max()

    Math.max(10, 20);  // Returns 20

    🔹 10. Statement Ends With → ;

    Every Java statement must end with a semicolon.

    int a = 5;

    🔹 11. Decision Making Keyword → if

    Used to check conditions.

    if (a > b) {
    System.out.println("A is greater");
}

    🔹 12. Default Value of int (Instance Variable) → 0

    • Applies only to instance variables, not local variables.

    🔹 13. Remainder Operator → %

    • Returns remainder after division.

    10 % 3  // 1

    🔹 14. Error During Execution → Runtime Error

    • Happens while program is running.

    • Example: Division by zero.

    🔹 15. Power Function → Math.pow()

    Math.pow(2, 3);  // 8.0

    🔹 16. Pre-Check Loops → for and while

    • Condition checked before execution.

    • May execute zero times.

    🔹 17. Increment Operator → ++

    • Increases value by 1.

    a++;  // or ++a;

    🔹 18. True/False Data Type → boolean

    Stores only:

    • true

    • false

    Example:

    boolean flag = true;

    🔹 19. Stop a Loop → break

    • Immediately terminates loop.

    Example:

    break;

    🔹 20. Assignment Operator → =

    • Used to assign value to variable.

    int x = 10;

    🎯 FINAL REVISION TIPS

    ✔ Know difference between = and ==
    ✔ Understand loop types clearly
    ✔ Remember Math functions
    ✔ Practice operator precedence
    ✔ Focus on errors (Syntax vs Runtime vs Logical)
    ✔ Revise increment/decrement carefully

    🔥 If you revise this note properly, you are fully prepared to score maximum marks in your Java exam!

✍ Important Theory & Programming Notes

🔹 Mathematical Statement in Java

Sum of a raised to b and cube root of c:

Math.pow(a, b) + Math.cbrt(c);

🔹 While vs Do-While Loop

whiledo-while
Condition checked firstCondition checked after execution
May execute 0 timesExecutes at least once

🔹 Final & If Concepts

  • final variable → ❌ Cannot be changed after initialization.

  • if statement → ✅ Can exist without else.

🔹 Logical Output

int x = 5;
System.out.println(x > 2 && x < 4);

✔ Output → false

(Because 5 is not less than 4)

🔹 Type Casting Types

  • double m = 'b'; → Implicit casting (Widening)

  • char ch = (char)68; → Explicit casting (Narrowing)

🔹 Post-Decrement Concept

int lives = 9;
System.out.println(lives--);
System.out.println(lives);

✔ Output:

9
8

(Post-decrement prints first, then decreases)

🔹 Syntax Error vs Logical Error

Syntax ErrorLogical Error
Violates grammar rulesProgram runs but gives wrong output
Found at compile timeFound after checking output

🔹 Creating Scanner Object

Scanner sc = new Scanner(System.in);

🔹 Creating Object of Class BANK

BANK obj = new BANK();

🔹 Expression Evaluation Trick

Expression:

3 * 9 % 5 * 2 / 2 * 7 % 5

Step-by-step (Left to Right for *, /, %):

3 * 9 = 27
27 % 5 = 2
2 * 2 = 4
4 / 2 = 2
2 * 7 = 14
14 % 5 = 4

✔ Final Answer → 4

🎯 Final Exam Tips

  • Remember operator precedence: *, /, % (Left to Right)

  • Know difference between = and ==

  • Understand loop conditions clearly

  • Practice Math functions

  • Focus on type casting and increment/decrement

🌟 JAVA PROGRAMMING SECTION – SOLVED & RESHUFFLED (With 5 Extra Questions) 🌟

(Perfect Practice Set for Full Marks – 15 Marks Each)


🔹 Question 1

Write a program to display an ATM Menu with the following options:

  • Check Balance

  • Withdraw Money

  • Deposit Money

Use if–else statements to perform the selected operation.

import java.util.Scanner;

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

        double balance = 10000;
        System.out.println("1. Check Balance");
        System.out.println("2. Withdraw Money");
        System.out.println("3. Deposit Money");
        System.out.print("Enter your choice: ");
        int choice = sc.nextInt();

        if (choice == 1) {
            System.out.println("Balance = " + balance);
        } 
        else if (choice == 2) {
            System.out.print("Enter amount to withdraw: ");
            double amount = sc.nextDouble();
            if (amount <= balance) {
                balance -= amount;
                System.out.println("Remaining Balance = " + balance);
            } else {
                System.out.println("Insufficient Balance");
            }
        } 
        else if (choice == 3) {
            System.out.print("Enter amount to deposit: ");
            double amount = sc.nextDouble();
            balance += amount;
            System.out.println("Updated Balance = " + balance);
        } 
        else {
            System.out.println("Invalid Choice");
        }
    }
}

🔹 Question 2

Write a program to generate and display the first 10 terms of the Fibonacci series.

public class Fibonacci {
    public static void main(String[] args) {
        int a = 0, b = 1, c;

        System.out.print(a + " " + b + " ");

        for (int i = 3; i <= 10; i++) {
            c = a + b;
            System.out.print(c + " ");
            a = b;
            b = c;
        }
    }
}

🔹 Question 3

Write a program to find the sum of digits of an integer.

import java.util.Scanner;

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

        System.out.print("Enter a number: ");
        int num = sc.nextInt();
        int sum = 0;

        while (num != 0) {
            sum += num % 10;
            num /= 10;
        }

        System.out.println("Sum of the digits = " + sum);
    }
}

🔹 Question 4

Write a program to calculate the GCD using the continued division method.

import java.util.Scanner;

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

        System.out.print("Enter first number: ");
        int a = sc.nextInt();
        System.out.print("Enter second number: ");
        int b = sc.nextInt();

        int remainder;

        while (b != 0) {
            remainder = a % b;
            a = b;
            b = remainder;
        }

        System.out.println("GCD = " + a);
    }
}

🔹 Question 5

Write a program to calculate volume of solids.

import java.util.Scanner;

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

        // Cube
        System.out.print("Enter side of cube: ");
        double side = sc.nextDouble();
        System.out.println("Volume of Cube = " + (side * side * side));

        // Cylinder
        System.out.print("Enter radius of cylinder: ");
        double r = sc.nextDouble();
        System.out.print("Enter height of cylinder: ");
        double h = sc.nextDouble();
        System.out.println("Volume of Cylinder = " + (Math.PI * r * r * h));

        // Sphere
        System.out.print("Enter radius of sphere: ");
        double rs = sc.nextDouble();
        System.out.println("Volume of Sphere = " + ((4.0/3) * Math.PI * rs * rs * rs));
    }
}

🔹 Question 

Write a program to check whether a number is Palindrome.

import java.util.Scanner;

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

        System.out.print("Enter number: ");
        int num = sc.nextInt();
        int original = num;
        int reverse = 0;

        while (num != 0) {
            reverse = reverse * 10 + num % 10;
            num /= 10;
        }

        if (original == reverse)
            System.out.println("Palindrome Number");
        else
            System.out.println("Not a Palindrome");
    }
}

🔹 Question 7

Write a program to check whether a number is Prime.

import java.util.Scanner;

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

        System.out.print("Enter number: ");
        int num = sc.nextInt();
        boolean prime = true;

        if (num <= 1)
            prime = false;

        for (int i = 2; i <= num / 2; i++) {
            if (num % i == 0) {
                prime = false;
                break;
            }
        }

        if (prime)
            System.out.println("Prime Number");
        else
            System.out.println("Not Prime");
    }
}

🔹 Question 8 

Write a program to find factorial of a number.

import java.util.Scanner;

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

        System.out.print("Enter number: ");
        int num = sc.nextInt();
        int fact = 1;

        for (int i = 1; i <= num; i++) {
            fact *= i;
        }

        System.out.println("Factorial = " + fact);
    }
}

🔹 Question 9 

Write a program to reverse a number.

import java.util.Scanner;

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

        System.out.print("Enter number: ");
        int num = sc.nextInt();
        int reverse = 0;

        while (num != 0) {
            reverse = reverse * 10 + num % 10;
            num /= 10;
        }

        System.out.println("Reversed Number = " + reverse);
    }
}

Here are extra Menu-Driven Programs with answers (Very Important for Exams – 15 Marks type questions).

🌟 1️⃣ Menu Driven Program – Simple Calculator

👉 Program to perform:

  • Addition

  • Subtraction

  • Multiplication

  • Division

import java.util.Scanner;

public class CalculatorMenu {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("1. Addition");
        System.out.println("2. Subtraction");
        System.out.println("3. Multiplication");
        System.out.println("4. Division");

        System.out.print("Enter your choice: ");
        int choice = sc.nextInt();

        System.out.print("Enter first number: ");
        double a = sc.nextDouble();

        System.out.print("Enter second number: ");
        double b = sc.nextDouble();

        if (choice == 1) {
            System.out.println("Result = " + (a + b));
        }
        else if (choice == 2) {
            System.out.println("Result = " + (a - b));
        }
        else if (choice == 3) {
            System.out.println("Result = " + (a * b));
        }
        else if (choice == 4) {
            if (b != 0)
                System.out.println("Result = " + (a / b));
            else
                System.out.println("Division by zero not allowed");
        }
        else {
            System.out.println("Invalid Choice");
        }
    }
}

🌟 2️⃣ Menu Driven Program – Number Operations

👉 Options:

  • Check Even or Odd

  • Check Prime

  • Find Factorial

import java.util.Scanner;

public class NumberMenu {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("1. Check Even/Odd");
        System.out.println("2. Check Prime");
        System.out.println("3. Find Factorial");

        System.out.print("Enter your choice: ");
        int choice = sc.nextInt();

        System.out.print("Enter a number: ");
        int num = sc.nextInt();

        if (choice == 1) {
            if (num % 2 == 0)
                System.out.println("Even Number");
            else
                System.out.println("Odd Number");
        }

        else if (choice == 2) {
            boolean prime = true;

            if (num <= 1)
                prime = false;

            for (int i = 2; i <= num / 2; i++) {
                if (num % i == 0) {
                    prime = false;
                    break;
                }
            }

            if (prime)
                System.out.println("Prime Number");
            else
                System.out.println("Not Prime");
        }

        else if (choice == 3) {
            int fact = 1;
            for (int i = 1; i <= num; i++) {
                fact *= i;
            }
            System.out.println("Factorial = " + fact);
        }

        else {
            System.out.println("Invalid Choice");
        }
    }
}

🌟 3️⃣ Menu Driven Program – Area Calculator

👉 Options:

  • Area of Circle

  • Area of Rectangle

  • Area of Triangle

import java.util.Scanner;

public class AreaMenu {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("1. Area of Circle");
        System.out.println("2. Area of Rectangle");
        System.out.println("3. Area of Triangle");

        System.out.print("Enter your choice: ");
        int choice = sc.nextInt();

        if (choice == 1) {
            System.out.print("Enter radius: ");
            double r = sc.nextDouble();
            System.out.println("Area = " + (Math.PI * r * r));
        }

        else if (choice == 2) {
            System.out.print("Enter length: ");
            double l = sc.nextDouble();
            System.out.print("Enter breadth: ");
            double b = sc.nextDouble();
            System.out.println("Area = " + (l * b));
        }

        else if (choice == 3) {
            System.out.print("Enter base: ");
            double base = sc.nextDouble();
            System.out.print("Enter height: ");
            double h = sc.nextDouble();
            System.out.println("Area = " + (0.5 * base * h));
        }

        else {
            System.out.println("Invalid Choice");
        }
    }
}

🔥 EXAM TIP (Very Important)

✔ Always display menu first
✔ Take input using Scanner
✔ Use if–else or switch
✔ Handle invalid choice
✔ Handle special cases (like division by zero)

If you want, I can also give:

  • ⭐ Menu Driven using switch

  • ⭐ Menu Driven using do-while (repeat menu)

  • ⭐ ICSE Board style 15-mark answer format

  • ⭐ Advanced menu (Banking system full version)

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