Exercises Java with Examples-
Practice Exercises Java 4,5 5 302940

Exercise tasks - Practice Exercises Java


Lesson 4:

Structures and Strings


Exercise 4.24:

Exercise tasks


Objetive:

Create a Java program that can store up to 2000 "to-do tasks". For each task, it must keep the following data:

• Date (a set of 3 data: day, month and year)
• Description of task
• Level of importance (1 to 10)
• Category

The program should allow the user the following operations:

1 - Add a new task (the date must "seem correct": day 1 to 31, month 1 to 12, year between 1000 and 3000).

2 - Show the tasks between two certain dates (day, month and year). If the user presses Enter without specifying date, it will be taken as "today". It must display the number of each record, the date (DD/ MM/YYYY), description, category and importance, all in the same line, separated with hyphens.

3 - Find tasks that contain a certain text (in description or category, not case sensitive). It will display number, date and description (only 50 letters, in case it was be longer). The user should be notified if none is found.

4 - Update a record (it will ask for the number, will display the previous value of each field and the user can press Enter not to modify any of the data). The user should be warned (but not asked again) if he enters an incorrect record number. It is not necessary to validate any of the fields.

5 - Delete some data, between two positions indicated by the user. The user should be warned (but not asked again) if he enters any incorrect record number. Each record to be deleted must be displayed, and the user must be asked for confirmation.

6 - Sort the data alphabetically by date and (if two dates are the same) by description.

7 - Find Duplicates: If two records have the same description, both will be displayed on-screen.

Q - Quit (end the application; as we do not store the information, it will be lost).

(Hint: you can know the current date using DateTime.Now.Day, DateTime.Now.Month and DateTime.Now.Year).


Source Code:


import java.util.*;
public class Main
{
	private final static class DateType
	{
		public short year;
		public byte month;
		public byte day;

		public DateType clone()
		{
			DateType varCopy = new DateType();

			varCopy.year = this.year;
			varCopy.month = this.month;
			varCopy.day = this.day;

			return varCopy;
		}
	}

	private final static class TaskType
	{
		public DateType date = new DateType();
		public String description;
		public byte level;
		public String category;

		public TaskType clone()
		{
			TaskType varCopy = new TaskType();

			varCopy.date = this.date.clone();
			varCopy.description = this.description;
			varCopy.level = this.level;
			varCopy.category = this.category;

			return varCopy;
		}
	}

	public static void main(String[] args)
	{
		int capacity = 2000;
		TaskType[] tasks = new TaskType[capacity];
		char option;
		int counter = 0;
		String search, newValue;
		boolean found;

		do
		{
			System.out.println();
			System.out.println("Tasks database");
			System.out.println();
			System.out.println("1- Add a new task.");
			System.out.println("2- Show the tasks between two certain dates.");
			System.out.println("3- Find tasks that contain a certain text.");
			System.out.println("4- Update a record.");
			System.out.println("5- Delete some data, between two positions indicated.");
			System.out.println("6- Sort the data alphabetically by date.");
			System.out.println("7- Find Duplicates.");
			System.out.println("Q- Quit.");
			System.out.println("Enter an option:");
			option = (char)(new Scanner(System.in).nextLine().toUpperCase());

			switch (option)
			{
				case '1': //Add a new task
					if (counter < capacity)
					{
						System.out.print("Enter the Description of the task: ");
						tasks[counter].description = new Scanner(System.in).nextLine();

						System.out.print("Enter the Level of the task (1-10): ");
						tasks[counter].level = Byte.parseByte(new Scanner(System.in).nextLine());

						System.out.print("Enter the Category of the task: ");
						tasks[counter].category = new Scanner(System.in).nextLine();

						do
						{
							System.out.print("Enter the Day of the task (1 to 31): ");
							tasks[counter].date.day = Byte.parseByte(new Scanner(System.in).nextLine());
							if (tasks[counter].date.day < 1 || tasks[counter].date.day > 31)
							{
								System.out.println("Not a valid day!");
							}
						} while (tasks[counter].date.day < 1 || tasks[counter].date.day > 31);

						do
						{
							System.out.print("Enter the Month of the task (1 to 12): ");
							tasks[counter].date.month = Byte.parseByte(new Scanner(System.in).nextLine());
							if (tasks[counter].date.month < 1 || tasks[counter].date.month > 12)
							{
								System.out.println("Not a valid month!");
							}
						} while (tasks[counter].date.month < 1 || tasks[counter].date.month > 12);

						do
						{
							System.out.print("Enter the Year of the task: ");
							tasks[counter].date.year = Short.parseShort(new Scanner(System.in).nextLine());
							if (tasks[counter].date.year < 1000 || tasks[counter].date.year > 3000)
							{
								System.out.println("Not a valid year!");
							}
						} while (tasks[counter].date.year < 1000 || tasks[counter].date.year > 3000);
						counter++;
					}
					else
					{
						System.out.println("Database full.");
					}
					break;

				case '2': //Show the tasks between two certain dates
					if (counter >= 1)
					{
						byte startDay, startMonth;
						short startYear;
						byte endDay, endMonth;
						short endYear;

						System.out.println("Starting day: ");
						String number = new Scanner(System.in).nextLine();

						if (number.equals(""))
						{
							startDay = (byte)java.time.LocalDateTime.now().getDayOfMonth();
						}
						else
						{
							startDay = Byte.parseByte(number);
						}

						System.out.println("Starting month: ");
						number = new Scanner(System.in).nextLine();
						if (number.equals(""))
						{
							startMonth = (byte)java.time.LocalDateTime.now().getMonthValue();
						}
						else
						{
							startMonth = Byte.parseByte(number);
						}

						System.out.println("Starting year: ");
						number = new Scanner(System.in).nextLine();
						if (number.equals(""))
						{
							startYear = (short)java.time.LocalDateTime.now().getYear();
						}
						else
						{
							startYear = Short.parseShort(number);
						}

						System.out.println("Final day: ");
						number = new Scanner(System.in).nextLine();
						if (number.equals(""))
						{
							endDay = (byte)java.time.LocalDateTime.now().getDayOfMonth();
						}
						else
						{
							endDay = Byte.parseByte(number);
						}

						System.out.println("Final month: ");
						number = new Scanner(System.in).nextLine();
						if (number.equals(""))
						{
							endMonth = (byte)java.time.LocalDateTime.now().getMonthValue();
						}
						else
						{
							endMonth = Byte.parseByte(number);
						}

						System.out.println("Final year: ");
						number = new Scanner(System.in).nextLine();
						if (number.equals(""))
						{
							endYear = (short)java.time.LocalDateTime.now().getYear();
						}
						else
						{
							endYear = Short.parseShort(number);
						}

						String startDate = "" + startYear + (new Byte(startMonth)).toString("00") + (new Byte(startDay)).toString("00");

						String endDate = "" + endYear + (new Byte(endMonth)).toString("00") + (new Byte(endDay)).toString("00");

						for (int i = 0; i < counter; i++)
						{
							String currentDate = "" + tasks[i].date.year + (new Byte(tasks[i].date.month)).toString("00") + (new Byte(tasks[i].date.day)).toString("00");
							if (currentDate.compareTo(startDate) >= 0 && currentDate.compareTo(endDate) <= 0)
							{
								System.out.printf("The number is %1$s: %2$s/%3$s/" + "%4$s - %5$s - %6$s - %7$s." + "\r\n", i + 1, tasks[i].date.day, tasks[i].date.month, tasks[i].date.year, tasks[i].description, tasks[i].category, tasks[i].level);
							}
						}
					}
					else
					{
						System.out.println("Database empty.");
					}
					break;

				case '3': //Find tasks that contain a certain text
					if (counter >= 1)
					{
						System.out.print("Enter the text to search: ");
						search = new Scanner(System.in).nextLine();
						found = false;
						String newValue5;

						for (int i = 0; i < counter; i++)
						{
							if (tasks[i].description.indexOf(search) >= 0 || tasks[i].category.indexOf(search) >= 0)
							{
								if (tasks[i].description.length() > 50)
								{
									newValue5 = tasks[i].description.substring(0, 50);
								}
								else
								{
									newValue5 = tasks[i].description;
								}

								found = true;
								System.out.printf("%1$s: %2$s/%3$s/%4$s - %5$s" + "\r\n", i + 1, tasks[i].date.day, tasks[i].date.month, tasks[i].date.year, newValue5);
							}
						}
						if (!found)
						{
							System.out.println("Not found.");
						}
					}
					else
					{
						System.out.println("Database empty.");
					}
					break;

				case '4': //Update a record
					if (counter >= 1)
					{
						System.out.print("Enter the number of the task to update: ");
						int update = Integer.parseInt(new Scanner(System.in).nextLine()) - 1;
						if ((update >= 0) && (update < counter))
						{
							System.out.printf("Description (%1$s): ", tasks[update].description);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].description = newValue;
							}

							System.out.printf("Level (%1$s): " + "\r\n", tasks[update].level);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].level = Byte.parseByte(newValue);
							}

							System.out.printf("Category (%1$s): " + "\r\n", tasks[update].category);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].category = newValue;
							}

							System.out.printf("Year (%1$s): " + "\r\n", tasks[update].date.year);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].date.year = Short.parseShort(newValue);
							}

							System.out.printf("Month (%1$s): " + "\r\n", tasks[update].date.month);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].date.month = Byte.parseByte(newValue);
							}

							System.out.printf("Day (%1$s): " + "\r\n", tasks[update].date.day);
							newValue = new Scanner(System.in).nextLine();
							if (!newValue.equals(""))
							{
								tasks[update].date.day = Byte.parseByte(newValue);
							}
						}
						else
						{
							System.out.println("Wrong number entered.");
						}
					}
					else
					{
						System.out.println("Database empty.");
					}
					break;

				case '5': //Delete some data, between two positions indicated by the user
					if (counter >= 1)
					{
						System.out.print("Enter the first number of data to delete: ");
						int delete = Integer.parseInt(new Scanner(System.in).nextLine()) - 1;
						System.out.print("Enter the second number of data to delete: ");
						int delete2 = Integer.parseInt(new Scanner(System.in).nextLine()) - 1;

						for (int pos = delete; pos <= delete2; pos++)
						{
							for (int i = delete; i < counter; i++)
							{
								tasks[i] = tasks[i + 1].clone();
							}
							counter--;
						}
					}
					else
					{
						System.out.println("Database empty.");
					}
					break;

				case '6': //Sort the data alphabetically on date + description
					for (int i = 0; i < counter - 1; i++)
					{
						String firstDate = "" + tasks[i].date.year + (new Byte(tasks[i].date.month)).toString("00") + (new Byte(tasks[i].date.day)).toString("00") + tasks[i].description;
						for (int j = i + 1; j < counter; j++)
						{
							String secondDate = "" + tasks[j].date.year + (new Byte(tasks[j].date.month)).toString("00") + (new Byte(tasks[j].date.day)).toString("00") + tasks[j].description;

							if (firstDate.compareTo(secondDate) > 0)
							{
								TaskType aux = tasks[i].clone();
								tasks[i] = tasks[j].clone();
								tasks[j] = aux.clone();
							}
						}
					}
					break;

				case '7': //Find Duplicates
					for (int i = 0; i < counter - 1; i++)
					{
						for (int j = i + 1; j < counter; j++)
						{
							if (tasks[i].description.equals(tasks[j].description))
							{
								System.out.printf("%1$s - %2$s/%3$s/%4$s" + "\r\n", tasks[i].description, tasks[i].date.day, tasks[i].date.month, tasks[i].date.year);
								System.out.printf("%1$s - %2$s/%3$s/%4$s" + "\r\n", tasks[j].description, tasks[j].date.day, tasks[j].date.month, tasks[j].date.year);
							}
						}
					}
					break;

				case 'Q': //Quit
					System.out.println("Quitting...");
					break;

				default:
					System.out.println("You entered a wrong option. Please re-enter it.");
					break;
			}
		} while (option != 'Q');
	}
}
Exercisey 4.24

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