Practice Question:

Variable Declaration and Initialization:

a) Write a Java program to declare and initialize an integer variable with the value 10. Print the value of the variable.

b) Write a Java program to declare and initialize a double variable with the value 3.14.

Feel free to attempt these questions and share your solutions in the group to practice variable declaration and initialization in Java!

public class Main {
    public static void main(String[] args) {
        int number = 10;
        System.out.println("The value of the variable is: " + number);
    }
}

public class Main {
    public static void main(String[] args) {
        double pi = 3.14;
        System.out.println("The value of the variable is: " + pi);
    }
}

   import java.util.Scanner;
   

   Scanner scanner = new Scanner(System.in);
   

   import java.util.Scanner;

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

           System.out.print("Enter your name: ");
           String name = scanner.nextLine();

           System.out.println("Hello, " + name + "!");
       }
   }
   

Student Information:
Name: John Doe
Age: 18
Favorite Subject: Mathematics

import java.util.Scanner;

public class StudentInformationDisplay {
    public static void main(String[] args) {
        // Declare variables
        String name;
        int age;
        String favoriteSubject;

        // Create a Scanner object to read input
        Scanner scanner = new Scanner(System.in);

        // Prompt the user to enter student information
        System.out.print("Enter student's name: ");
        name = scanner.nextLine();

        System.out.print("Enter student's age: ");
        age = Integer.parseInt(scanner.nextLine());

        System.out.print("Enter student's favorite subject: ");
        favoriteSubject = scanner.nextLine();

        // Close the scanner
        scanner.close();

        // Display the student information
        System.out.println("Student Information:");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Favorite Subject: " + favoriteSubject);
    }
}

   Example:
   int a = 10;
   int b = 3;

   int sum = a + b;
   int difference = a - b;
   int product = a * b;
   int quotient = a / b;
   int remainder = a % b;

   System.out.println("a + b = " + sum);
   System.out.println("a - b = " + difference);
   System.out.println("a * b = " + product);
   System.out.println("a / b = " + quotient);
   System.out.println("a % b = " + remainder);

   // Increment and decrement
   int c = 5;
   System.out.println("Initial value of c: " + c);
   c++; // Increment c by 1
   System.out.println("After incrementing: " + c);
   c--; // Decrement c by 1
   System.out.println("After decrementing: " + c);
   

   Example:
   int a = 5;
   int b = 10;

   System.out.println(a + " == " + b + " is " + (a == b));
   System.out.println(a + " != " + b + " is " + (a != b));
   System.out.println(a + " > " + b + " is " + (a > b));
   System.out.println(a + " < " + b + " is " + (a < b));
   System.out.println(a + " >= " + b + " is " + (a >= b));
   System.out.println(a + " <= " + b + " is " + (a <= b));
   

      int y = 7;
      y++; // Increment by 1 (equivalent to y = y + 1;)
      y--; // Decrement by 1 (equivalent to y = y - 1;)
      

public class AssignmentOperatorsExample {
    public static void main(String[] args) {
        int x = 5;
        System.out.println("Initial value of x: " + x);

        x += 3;
        System.out.println("After addition: " + x);

        x -= 2;
        System.out.println("After subtraction: " + x);

        x *= 4;
        System.out.println("After multiplication: " + x);

        x /= 2;
        System.out.println("After division: " + x);

        x %= 3;
        System.out.println("After modulo: " + x);

        int y = 7;
        System.out.println("Initial value of y: " + y);

        y++;
        System.out.println("After increment: " + y);

        y--;
        System.out.println("After decrement: " + y);
    }
}

Initial value of x: 5
After addition: 8
After subtraction: 6
After multiplication: 24
After division: 12
After modulo: 0
Initial value of y: 7
After increment: 8
After decrement: 7

public class BitwiseOperatorsExample {
    public static void main(String[] args) {
        int a = 5; // Binary: 0101
        int b = 3; // Binary: 0011

        int resultAnd = a & b;
        System.out.println("Bitwise AND: " + resultAnd); // Output: 1 (Binary: 0001)

        int resultOr = a | b;
        System.out.println("Bitwise OR: " + resultOr); // Output: 7 (Binary: 0111)

        int resultXor = a ^ b;
        System.out.println("Bitwise XOR: " + resultXor); // Output: 6 (Binary: 0110)

        int resultNotA = ~a;
        System.out.println("Bitwise NOT of a: " + resultNotA); // Output: -6 (Binary: 11111111111111111111111111111010)

        int resultLeftShift = a << 2;
        System.out.println("Left Shift: " + resultLeftShift); // Output: 20 (Binary: 10100)

        int resultRightShift = a >> 1;
        System.out.println("Right Shift: " + resultRightShift); // Output: 2 (Binary: 0010)

        int resultUnsignedRightShift = a >>> 1;
        System.out.println("Unsigned Right Shift: " + resultUnsignedRightShift); // Output: 2 (Binary: 0010)
    }
}

Bitwise AND: 1
Bitwise OR: 7
Bitwise XOR: 6
Bitwise NOT of a: -6
Left Shift: 20
Right Shift: 2
Unsigned Right Shift: 2

[Insert the provided code in the code block here]

Summary Report:
-------------------------
Student: John Doe
Average Grade: 90.0
Final Grade: A

Student: Jane Smith
Average Grade: 81.0
Final Grade: B

Student: Michael Johnson
Average Grade: 91.66666666666667
Final Grade: A

import java.util.Scanner;

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

        // Get the number of students
        System.out.print("Enter the number of students: ");
        int numStudents = scanner.nextInt();

        // Create arrays to store student information
        String[] studentNames = new String[numStudents];
        double[] homeworkGrades = new double[numStudents];
        double[] quizGrades = new double[numStudents];
        double[] examGrades = new double[numStudents];
        double[] averageGrades = new double[numStudents];
        String[] finalGrades = new String[numStudents];

        // Get grades for each student
        for (int i = 0; i < numStudents; i++) {
            scanner.nextLine(); // Consume the newline character
            System.out.println("Enter details for Student " + (i + 1) + ":");
            System.out.print("Name: ");
            studentNames[i] = scanner.nextLine();
            System.out.print("Homework Grade: ");
            homeworkGrades[i] = scanner.nextDouble();
            System.out.print("Quiz Grade: ");
            quizGrades[i] = scanner.nextDouble();
            System.out.print("Exam Grade: ");
            examGrades[i] = scanner.nextDouble();

            // Calculate average grade for the student
            averageGrades[i] = (homeworkGrades[i] + quizGrades[i] + examGrades[i]) / 3;

            // Determine final grade category
            if (averageGrades[i] >= 90) {
                finalGrades[i] = "A";
            } else if (averageGrades[i] >= 80) {
                finalGrades[i] = "B";
            } else if (averageGrades[i] >= 70) {
                finalGrades[i] = "C";
            } else if (averageGrades[i] >= 60) {
                finalGrades[i] = "D";
            } else {
                finalGrades[i] = "F";
            }
        }

        // Print summary report
        System.out.println("\nSummary Report:");
        System.out.println("-------------------------");
        for (int i = 0; i < numStudents; i++) {
            System.out.println("Student: " + studentNames[i]);
            System.out.println("Average Grade: " + averageGrades[i]);
            System.out.println("Final Grade: " + finalGrades[i]);
            System.out.println("-------------------------");
        }
    }
}

if (condition) {
    // Code to execute if the condition is true
} else if (condition2) {
    // Code to execute if condition2 is true
} else {
    // Code to execute if none of the conditions are true
}

int age = 18;
if (age >= 18) {
    System.out.println("You are an adult. 👤");
} else {
    System.out.println("You are not yet an adult. 🧒");
}

You are an adult. 👤

switch (expression) {
    case value1:
        // Code to execute if expression matches value1
        break;
    case value2:
        // Code to execute if expression matches value2
        break;
    // Additional cases
    default:
        // Code to execute if expression does not match any case
}

int day = 3;
switch (day) {
    case 1:
        System.out.println("Monday. 🌤");
        break;
    case 2:
        System.out.println("Tuesday. 🌧");
        break;
    // Additional cases
    default:
        System.out.println("Invalid day. ❌");
}

Invalid day. ❌

for (initialization; condition; update) {
    // Code to execute in each iteration
}

for (int i = 1; i <= 5; i++) {
    System.out.println("Iteration: " + i + " ➰");
}

Iteration: 1 ➰
Iteration: 2 ➰
Iteration: 3 ➰
Iteration: 4 ➰
Iteration: 5 ➰

while (condition) {
    // Code to execute as long as the condition is true
}

int count = 0;
while (count < 5) {
    System.out.println("Count: " + count + " 🔄");
    count++;
}

Count: 0 🔄
Count: 1 🔄
Count: 2 🔄
Count: 3 🔄
Count: 4 🔄

do {
    // Code to execute
} while (condition);

int x = 1;
do {
    System.out.println("Value of x: " + x + " 🔄");
    x++;
} while (x <= 5);

Value of x: 1 🔄
Value of x: 2 🔄
Value of x: 3 🔄
Value of x: 4 🔄
Value of x: 5 🔄

for (int i = 1; i <= 10; i++) {
    if (i == 5) {
        break; // Exit the loop when i is 5
    }
    System.out.println("Value of i: " + i + " ➡️");
}

Example:
```java
for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue; // Skip the rest of the code and go to the next iteration when i is 3
    }
    System.out.println("Value of i: " + i + " ➡️");
}

Value of i: 1 ➡️
Value of i: 2 ➡️
Value of i: 4 ➡️
Value of i: 5 ➡️