Basic Java Program for Beginners

Author: J-B-Mugundh

Bug3524.java

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+import java.util.Scanner;
+public class Bug3524 {
+        public static void main(String[] param) {
+            System.out.println("2021503524 - Mugundh J B - 09/09/23 - 2.20 pm");
+            Scanner in = new Scanner(System.in);
+            System.out.println("Hello. Please type your name:");
+            String name = in.nextLine();
+            System.out.println("Hello "+name);
+            System.out.println ("Have a, nice day!");
+        }
+}

Temp3524.java

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+import java.util.Scanner;
+import java.text.DecimalFormat;
+public class Temp3524 {
+    public static void main(String[] args){
+        Scanner in = new Scanner(System.in);
+        System.out.println("2021503524 - Mugundh J B - 09/09/23 - 2.40 pm");
+        System.out.print("Enter temperature in Fahrenheit: ");
+        float fah = in.nextFloat();
+        float c = (fah - 32) * 5 / 9;
+        DecimalFormat df = new DecimalFormat("0.00"); // Used to format the decimal value in form of pattern
+        System.out.printf("Fahrenheit temperature " + df.format(fah) +
+                " is the same \nas " + df.format(c) + " degrees Celsius.");
+    }
+}

Verbalize3524.java

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+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.Scanner;
+public class Verbalize3524{
+    // Arrays to store the verbal representations of units and tens
+    private static final String[] units = {
+            "", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten",
+            "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"
+    };
+    private static final String[] tens = {
+            "", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"
+    };
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.println("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+        Scanner scanner = new Scanner(System.in);
+        System.out.print("Enter a number between 1 and 9999: ");
+        int number = scanner.nextInt();
+        // Check for invalid input
+        while (number < 1 || number > 9999) {
+            System.out.print("Invalid input. Please enter a number between 1 and 9999: ");
+            number = scanner.nextInt();
+        }
+        // Convert the number to its verbal representation
+        String verbalized = convertToWords(number);
+        System.out.printf("Verbalized form:\n" + verbalized);
+    }
+    // Convert a number to its verbal representation
+    public static String convertToWords(int number) {
+        if (number < 20) {
+            return units[number]; // Directly use the units array
+        } else if (number < 100) {
+            return tens[number / 10] + " " + units[number % 10]; // Combine tens and units
+        } else if (number < 1000) {
+            return units[number / 100] + " Hundred and " + convertToWords(number % 100); // Handling hundreds by recursion
+        } else {
+            return units[number / 1000] + " Thousand and " + convertToWords(number % 1000); // Handling thousands by recursion
+        }
+    }
+}

dataType3524.java

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+public class dataType3524 {
+//    // Integer data types
+//    byte byteValue = 127; // Correct
+//    // byte byteValue = 128; // Incorrect: Value exceeds the valid range (-128 to 127)
+//    long longValue = 9223372036854775807; // Incorrect, require L at the end
+//    long longValue = 9223372036854775807L; // Correct
+//    long longValue = 9223372036854775807; // Incorrect, require L at the end
+//    long longValue = 9223372036854775808L; // Incorrect: Value exceeds the valid range
+//    // Floating-point data types
+//    float floatValue = 3.14f; // Correct
+//    float floatValue = 3.14; // Incorrect: Floating-point literals need 'f' or 'F' suffix
+//    // Boolean data type
+//    double doubleValue = 3.14159; // Correct
+//    // Character data type
+//    char charValue = 'A'; // Correct
+//    char charValue = "A"; // Incorrect: Use single quotes for characters
+//    boolean booleanValue = true; // Correct
+//    boolean booleanValue = 0; // Incorrect: Use 'true' or 'false' for boolean values
+}

dateTime3524.java

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+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+public class dateTime3524 {
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B \n");
+        LocalDateTime current = LocalDateTime.now(); //"LocalDateTime" is the class
+        //"now()" is a method, represent the current date and time
+        DateTimeFormatter dateformat = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+        DateTimeFormatter timeformat = DateTimeFormatter.ofPattern("HH:mm:ss");
+        // ofPattern() is used to format the date in a particular pattern
+        String formattedDate = current.format(dateformat);
+        System.out.print("Date: " + formattedDate);
+        String formattedTime = current.format(timeformat);
+        System.out.println(" Time: " + formattedTime);
+    }
+}

digitalWatch3524.java

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+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.Scanner;
+public class digitalWatch3524 {
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.println("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+        Scanner scanner = new Scanner(System.in);
+        // Prompt the user for input
+        System.out.print("Input day (Mon, Tue, Wed, Thu, Fri, Sat, Sun): ");
+        String day = scanner.nextLine();
+        System.out.print("Input hour (24-hour): ");
+        int hour = scanner.nextInt();
+        System.out.print("Input minute: ");
+        int minute = scanner.nextInt();
+        System.out.print("Input second: ");
+        int second = scanner.nextInt();
+        // Validating day input
+        if (!isValidDay(day)) {
+            System.out.println("Invalid day input!");
+        } else if (hour < 0 || hour > 23 || minute < 0 || minute > 59 || second < 0 || second > 59) {
+            System.out.println("Invalid time input!");
+        } else {
+            // Advancing time by one second
+            second++;
+            if (second == 60) {
+                second = 0;
+                minute++;
+                if (minute == 60) {
+                    minute = 0;
+                    hour++;
+                    if (hour == 24) {
+                        hour = 0;
+                        day = getNextDay(day);
+                    }
+                }
+            }
+            // Displaying the new time
+            System.out.println("New time: " + day + " " + hour + " " + minute + " " + second);
+        }
+    }
+    // Checking if the given day is valid
+    public static boolean isValidDay(String day) {
+        return day.equals("Mon") || day.equals("Tue") || day.equals("Wed") ||
+                day.equals("Thu") || day.equals("Fri") || day.equals("Sat") || day.equals("Sun");
+    }
+    // Getting the next day
+    public static String getNextDay(String day) {
+        if (day.equals("Sun")) return "Mon";
+        if (day.equals("Mon")) return "Tue";
+        if (day.equals("Tue")) return "Wed";
+        if (day.equals("Wed")) return "Thu";
+        if (day.equals("Thu")) return "Fri";
+        if (day.equals("Fri")) return "Sat";
+        if (day.equals("Sat")) return "Sun";
+        return "";
+    }
+}

finalVelocity3524.java

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+import java.util.Scanner;
+public class finalVelocity3524 {
+    public static void main(String[] args){
+        Scanner in = new Scanner(System.in);
+        System.out.println("2021503524 - Mugundh J B - 09/09/23 - 3 pm");
+
+        System.out.print("Enter the starting speed: ");
+        float u = in.nextFloat();
+        System.out.print("Enter the acceleration: ");
+        float a = in.nextFloat();
+        System.out.print("Enter the time: ");
+        float t = in.nextFloat();
+
+        float d = (float) (u * t + (0.5 * a * t * t)); // Formula to calc displacement
+        System.out.printf("The displacement is %.2f", d);
+
+        float v = u + a * t; // Formula to calc final velocity
+        System.out.printf("\nThe final velocity is %.2f", v);
+
+    }
+}

headsTails3524.java

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+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.*;
+
+public class headsTails3524 {
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.println("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+
+        // Create a random number generator
+        Random rand = new Random();
+
+        // Generate a random number (0 or 1)
+        int num = rand.nextInt(2);
+
+        // Create a Scanner to read user input
+        Scanner in = new Scanner(System.in);
+
+        // Prompt the user for their choice
+        System.out.print("Enter your choice (h / H / t / T): ");
+        char choice = in.next().charAt(0);
+
+        // Validate user's choice
+        while (choice != 'h' && choice != 'H' && choice != 't' && choice != 'T') {
+            System.out.printf("Invalid choice. Enter your choice (h / H / t / T): ");
+            choice = in.next().charAt(0);
+        }
+
+        // Display the random value generated
+        System.out.printf("Random value = %d\n", num);
+
+        // Check if the user won or lost based on their choice and the random value
+        if (((choice == 'h' || choice == 'H') && num == 1) || ((choice == 't' || choice == 'T') && num == 0))
+            System.out.print("You won!");
+        else
+            System.out.print("You lose!");
+
+    }
+}

helloWorld3524.java

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+
+import java.time.LocalDate;
+import java.time.LocalTime;
+
+public class helloWorld3524 {
+    public static void main(String[] a) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.printf("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+        System.out.print("\nHello, ");
+        System.out.print(a[0]);
+        System.out.println("\nGood morning! ");
+    }
+}

monthDays3524.java

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+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.Scanner;
+
+public class monthDays3524 {
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.println("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter the year: ");
+        int year = scanner.nextInt(); // Getting the year as input
+
+        while (year < 1000 || year > 9999) { // Checking if the entered year is valid
+            System.out.printf("Invalid input for the year!\nEnter the year again: ");
+            year = scanner.nextInt(); // Getting input again if input is invalid
+        }
+        System.out.print("Enter the month (1 to 12): ");
+            int month = scanner.nextInt(); // Getting the month as input
+
+            int daysInMonth = 0; // Variable to store no of days in that month
+            switch(month){
+                case 1: case 3: case 5: case 7: case 8: case 10: case 12:
+                    daysInMonth = 31;
+                    break;
+                case 4: case 6: case 9: case 11:
+                    daysInMonth = 30;
+                    break;
+                case 2:
+                    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+                        daysInMonth = 29; // Leap year
+                    } else {
+                        daysInMonth = 28; // Non-leap year
+                    }
+                    break;
+                default:
+                    System.out.println("Invalid month!");
+                    return;
+            }
+            System.out.printf("Number of days in %d th month: %d", month,  daysInMonth);
+    }
+}

studentGrade3524.java

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+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.util.*;
+
+public class studentGrade3524 {
+    public static void main(String[] args) {
+        System.out.println("2021503524 - Mugundh J B");
+        System.out.println("Date: " + LocalDate.now() + " Time: " + LocalTime.now());
+        // Create a Scanner to read user input
+        Scanner in = new Scanner(System.in);
+        // Prompt the user for the number of subjects
+        System.out.print("Enter no of subjects: ");
+        int n = in.nextInt();
+        // Consume newline character left in buffer
+        String buff = in.nextLine();
+        // Initialize an array to store marks for each subject
+        int[] arr = new int[n];
+        // Prompt the user to enter marks for each subject and validate input
+        System.out.println("Enter the marks: ");
+        for (int i = 0; i < n; i++) {
+            arr[i] = in.nextInt();
+            if (arr[i] < 0 || arr[i] > 100) {
+                System.out.println("Invalid input! Enter again: ");
+                arr[i] = in.nextInt();
+            }
+        }
+        // Determine the grade for each subject based on marks and display it
+        for (int i = 0; i < n; i++) {
+            if (arr[i] >= 90 && arr[i] <= 100)
+                System.out.printf("Grade of subject %d = %s\n", i + 1, "O");
+            else if (arr[i] >= 80 && arr[i] <= 89)
+                System.out.printf("Grade of subject %d = %s\n", i + 1, "A+");
+            else if (arr[i] >= 70 && arr[i] <= 79)
+                System.out.printf("Grade of subject %d = %s\n", i + 1, "A");
+            else if (arr[i] >= 60 && arr[i] <= 69)
+                System.out.printf("Grade of subject %d = %s\n", i + 1, "B+");
+            else if (arr[i] >= 50 && arr[i] <= 59)
+                System.out.printf("Grade of subject %d = %s\n", i + 1, "B");
+            else
+                System.out.printf("Grade of subject %d = %s", i + 1, "U");
+        }
+    }
+}