Dienstplananwendung in Java

package delftstack;

public class CreateStudent {
  private String Student_Name;
  private int[] Student_Grades;

  // Default constructor
  public CreateStudent() {
    Student_Name = "";
    for (int i = 0; i < Student_Grades.length; i++) {
      Student_Grades[i] = 0;
    }
  }

  // Constructor with inputs
  public CreateStudent(String Name1, int[] Grade1) {
    Student_Grades = new int[3];
    SetStudentName(Name1);
    SetStudentGrades(Grade1);
  }

  // Return the name of the students
  public String GetStudentName() {
    return Student_Name;
  }

  // Return the grades of the student
  public int[] GetStudentGrades() {
    return Student_Grades;
  }

  // To store the Name
  public void SetStudentName(String Name1) {
    Student_Name = Name1;
  }

  // To store or set the grades
  public void SetStudentGrades(int[] Grade2) {
    for (int i = 0; i < Grade2.length; i++) {
      Student_Grades[i] = Grade2[i];
    }
  }

  // Return the name and grades in string
  public String ConverttoString() {
    return (
        Student_Name + " " + Student_Grades[0] + " " + Student_Grades[1] + " " + Student_Grades[2]);
  }

  // Returns the top grade
  public int GetTopGrade(int[] Grade3) {
    int top = Grade3[0];

    for (int x = 0; x < Grade3.length; x++) {
      if (top < Grade3[x]) {
        top = Grade3[x];
      }
    }
    return top;
  }
}

package delftstack;

import java.text.*;
import java.util.Vector;
import javax.swing.*;

public class MaintainStudent {
  // to determine the user input errors
  static int Error_Flag = 0;

  public static void main(String args[]) {
    // The default value for grades
    int[] Grade1 = {98, 99, 95};
    int[] Grade2 = {89, 93, 75};
    int[] Grade3 = {50, 45, 65};

    // The default Student record
    CreateStudent Student1 = new CreateStudent("Jack Sparrow", Grade1);
    CreateStudent Student2 = new CreateStudent("Frank Morgan", Grade2);
    CreateStudent Student3 = new CreateStudent("Forest Gump", Grade3);

    // Create A vector of 'students' objects
    Vector Students_Vector = new Vector();
    Students_Vector.add(Student1);
    Students_Vector.add(Student2);
    Students_Vector.add(Student3);

    String Option_Choice = "";
    String Option_Message = "";
    String Option_Text = "";
    String Option_Input = "";
    String Option_Record = "";

    // To keep track of the top grade
    int Top_Grade = 0;

    // To Hold the student's grade
    int[] Students_Grade = {0, 0};
    int Student_Index1 = 0;
    int Student_Index2 = 0;
    int Student_Index3 = 0;
    String Student_Grade_1 = "";
    String Student_Grade_2 = "";
    String Student_Grade_3 = "";
    int Gr_1 = 0;
    int Gr_2 = 0;
    int Gr_3 = 0;
    String Student_Name = "";

    // To validate of input
    boolean Retry_Student = false;
    // To validate if the name is found
    boolean Found_Student = false;

    try {
      while (!(Option_Choice.equalsIgnoreCase("Exit"))) {
        Option_Message = "";
        for (int i = 0; i < Students_Vector.size(); i++) {
          Option_Message =
              Option_Message + ((CreateStudent) Students_Vector.get(i)).ConverttoString() + "\n";
        }

        Option_Message = Option_Message
            + "\n\n\nType 'Add' press 'Ok' to add a student\nType 'Delete' and press 'Ok' to delete a student\nType 'View' and press 'Ok' to view a student's record\nType 'Exit' and press 'Ok' to exit:";

        Option_Choice = JOptionPane.showInputDialog(
            null, Option_Message, "Students Roster Application", JOptionPane.QUESTION_MESSAGE);

        if (Option_Choice.equalsIgnoreCase("Add")) {
          try {
            Option_Input = JOptionPane.showInputDialog(null,
                "Please enter student's name and grades\nwith no spaces between entries:\nFor Example: Sheeraz,87,88,99",
                "Input", JOptionPane.QUESTION_MESSAGE);
            Option_Input = Option_Input.trim();

            // Reset the flag
            Error_Flag = 0;

            Retry_Student = Input_Validation(Option_Input);

            if (1 == Error_Flag) {
              JOptionPane.showMessageDialog(null,
                  "Wrong Entry: Please Enter a name which begins with a Letter!\nPlease click OK to retry.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            } else if (2 == Error_Flag) {
              JOptionPane.showMessageDialog(null,
                  "Wrong Entry: The student's grade is missing!\nPlease click OK to retry.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            } else if (3 == Error_Flag) {
              JOptionPane.showMessageDialog(null,
                  "Worng Entry: Student's grades digit limit exceeded, please enter grades with three digits.!\nPlease click OK to retry.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            } else if (4 == Error_Flag) {
              JOptionPane.showMessageDialog(null,
                  "Worng Entry: Please enter a Student name it cannot be blank or ommitted!\nPlease click OK to retry.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            } else if (5 == Error_Flag) {
              JOptionPane.showMessageDialog(null,
                  "Wrong Entry: Please do not add Blank spaces \nbefore or after the full name, commas and grades!\nPlease click OK to retry.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            }

            // Check if the first input was invalid
            if (true == Retry_Student) {
              // ask the user for valid input
              while (true == Retry_Student) {
                Option_Input = JOptionPane.showInputDialog(null,
                    "Please Re-Enter student's info\nwith no spaces between entries:\nFor example: (Sheeraz Gul,87,88,99)",
                    "Input", JOptionPane.QUESTION_MESSAGE);
                Option_Input = Option_Input.trim();

                Retry_Student = Input_Validation(Option_Input);

                if (1 == Error_Flag) {
                  JOptionPane.showMessageDialog(null,
                      "Wrong Entery: Please Enter a name which begins with a Letter!\nPlease click OK to retry.",
                      "Error", JOptionPane.ERROR_MESSAGE);
                } else if (2 == Error_Flag) {
                  JOptionPane.showMessageDialog(null,
                      "Wrong Entry: The student's grade is missing!\nPlease click OK to retry.",
                      "Error", JOptionPane.ERROR_MESSAGE);
                } else if (3 == Error_Flag) {
                  JOptionPane.showMessageDialog(null,
                      "Worng Entry: Student's grades digit limit exceeded, please enter grades with three digits.!\nPlease click OK to retry.",
                      "Error", JOptionPane.ERROR_MESSAGE);
                } else if (4 == Error_Flag) {
                  JOptionPane.showMessageDialog(null,
                      "Worng Entry: Please enter a Student name it cannot be blank or ommitted!\nPlease click OK to retry.",
                      "Error", JOptionPane.ERROR_MESSAGE);
                } else if (5 == Error_Flag) {
                  JOptionPane.showMessageDialog(null,
                      "Wrong Entry: Please do not add Blank spaces \\nbefore or after the full name, commas and grades!\nPlease click OK to retry.",
                      "Error", JOptionPane.ERROR_MESSAGE);
                }

                // Reset the flag
                Error_Flag = 0;
              }
            }
          } catch (IndexOutOfBoundsException e) {
            Option_Input = JOptionPane.showInputDialog(null,
                "Please Re-Enter the student's Infor \nwith no spaces between entries:\nFor example: (Sheeraz,87,88,99)",
                "Input", JOptionPane.QUESTION_MESSAGE);
            Option_Input = Option_Input.trim();
          }

          // All the validation is done above; if everything is fine, process the user input.
          Student_Index1 = Option_Input.indexOf(",");
          Student_Index2 = Option_Input.indexOf(",", Student_Index1 + 1);
          Student_Index3 = Option_Input.indexOf(",", Student_Index2 + 1);

          Student_Name = Option_Input.substring(0, Student_Index1);
          Student_Grade_1 = Option_Input.substring(Student_Index1 + 1, Student_Index2);
          Student_Grade_2 = Option_Input.substring(Student_Index2 + 1, Student_Index3);
          Student_Grade_3 = Option_Input.substring(Student_Index3 + 1);

          // Remove the spaces
          Student_Name = Student_Name.trim();
          Student_Grade_1 = Student_Grade_1.trim();
          Student_Grade_2 = Student_Grade_2.trim();
          Student_Grade_3 = Student_Grade_3.trim();

          Gr_1 = Integer.parseInt(Student_Grade_1);
          Gr_2 = Integer.parseInt(Student_Grade_2);
          Gr_3 = Integer.parseInt(Student_Grade_3);

          Grade1[0] = Gr_1;
          Grade1[1] = Gr_2;
          Grade1[2] = Gr_3;

          Found_Student = false;

          // To update the student's record if it exists
          for (int p = 0; p < Students_Vector.size(); p++) {
            if (Student_Name.equals(((CreateStudent) Students_Vector.get(p)).GetStudentName())) {
              ((CreateStudent) Students_Vector.get(p)).SetStudentGrades(Grade1);
              Found_Student = true;
            }
          }

          // add the student to the roster if it doesn't exist.
          if (!Found_Student) {
            CreateStudent student = new CreateStudent(Student_Name, Grade1);
            Students_Vector.add(student);
          }
          // Inform the user
          else {
            JOptionPane.showMessageDialog(null,
                "The student, " + Student_Name + " is updated!\nPlease click OK to go back.",
                "Info", JOptionPane.INFORMATION_MESSAGE);
          }
        } else if (Option_Choice.equalsIgnoreCase("Delete")) {
          Option_Input = JOptionPane.showInputDialog(null,
              "Please enter student's name you want to delete:", "Input",
              JOptionPane.QUESTION_MESSAGE);
          Found_Student = false;

          // Search for a name and delete it.
          for (int i = 0; i < Students_Vector.size(); i++) {
            if (Option_Input.equals(((CreateStudent) Students_Vector.get(i)).GetStudentName())) {
              Students_Vector.remove(i);
              Found_Student = true;
              break;
            }
          }
          // Go back to the menu if the user info is not found.
          if (!Found_Student) {
            JOptionPane.showMessageDialog(null,
                "Please enter the correct name, this student does not exist!\nPlease click OK to go back.",
                "Error", JOptionPane.ERROR_MESSAGE);
          }
        } else if (Option_Choice.equalsIgnoreCase("View")) {
          Option_Input = JOptionPane.showInputDialog(null,
              "Please enter the student's name to view the record:", "Input",
              JOptionPane.QUESTION_MESSAGE);
          Found_Student = false;

          // Search for a name and show the record
          for (int m = 0; m < Students_Vector.size(); m++) {
            if (Option_Input.equals(((CreateStudent) Students_Vector.get(m)).GetStudentName())) {
              Students_Grade = ((CreateStudent) Students_Vector.get(m)).GetStudentGrades();
              Top_Grade = ((CreateStudent) Students_Vector.get(m)).GetTopGrade(Students_Grade);
              Option_Record = ((CreateStudent) Students_Vector.get(m)).ConverttoString()
                  + "\nThe Top Grade: " + Top_Grade;

              JOptionPane.showMessageDialog(
                  null, Option_Record, Option_Input, JOptionPane.INFORMATION_MESSAGE);
              Found_Student = true;
              break;
            }
          }
          // If no record is found, go back to the menu.
          if (!Found_Student) {
            JOptionPane.showMessageDialog(null,
                "Please enter the correct name, this student does not exist!\nPlease click OK to go back.",
                "Error", JOptionPane.ERROR_MESSAGE);
          }
        } else {
          // If the user types anything other than "Add", "Delete", "View", or "Exit", then inform
          // him.
          if (!(Option_Choice.equalsIgnoreCase("Exit"))) {
            if (Option_Choice.trim().equals("")) {
              JOptionPane.showMessageDialog(null,
                  "Please first make a selection then click OK!\nPlease click OK to go back.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            } else {
              JOptionPane.showMessageDialog(null,
                  "Please enter the correct option, this option does not exist!\nPlease click OK to go back.",
                  "Error", JOptionPane.ERROR_MESSAGE);
            }
          }
        }
      }
    } catch (NullPointerException e) {
      System.exit(0);
    }

    System.exit(0);
  }

  // For input validation
  private static boolean Input_Validation(String Demo_String) {
    boolean R_Value = false;

    int Comma_Count = 0;
    int Index1_Comma = 0;
    int Index2_Comma = 0;
    int Index3_Comma = 0;
    char Comma_Char;
    boolean Comma_Position = true;

    String String_Name = "";
    String String_Grade1 = "";
    String String_Grade2 = "";
    String String_Grade3 = "";
    int String_Grade_1 = 0;
    int String_Grade_2 = 0;
    int String_Grade_3 = 0;

    // Check for a blank string
    if ((0 == Demo_String.length()) || (Demo_String.equals(""))) {
      R_Value = true;
    }

    // Check for commas
    for (int i = 0; i < Demo_String.length(); i++) {
      if ((Demo_String.charAt(i)) == ',') {
        Comma_Count++;
      }
    }

    // Check for the positions of commas and make sure there are three commas
    if (3 == Comma_Count) {
      Index1_Comma = Demo_String.indexOf(",");
      Index2_Comma = Demo_String.indexOf(",", Index1_Comma + 1);
      Index3_Comma = Demo_String.indexOf(",", Index2_Comma + 1);

      if (Index2_Comma == Index1_Comma + 1) {
        R_Value = true;
        Comma_Position = false;
      } else if (Index3_Comma == Index2_Comma + 1) {
        R_Value = true;
        Comma_Position = false;
      }
    } else {
      R_Value = true;
    }

    // Dissects the 'string' to store the data
    if ((3 == Comma_Count) && (true == Comma_Position)) {
      String_Name = Demo_String.substring(0, Index1_Comma);
      String_Grade1 = Demo_String.substring(Index1_Comma + 1, Index2_Comma);
      String_Grade2 = Demo_String.substring(Index2_Comma + 1, Index3_Comma);
      String_Grade3 = Demo_String.substring(Index3_Comma + 1);

      // Compare the string with the trimmed string because white spaces are not allowed.

      if (!(String_Name.equals(String_Name.trim()))) {
        Error_Flag = 5;
        R_Value = true;
      }
      if (!(String_Grade1.equals(String_Grade1.trim()))) {
        Error_Flag = 5;
        R_Value = true;
      }
      if (!(String_Grade2.equals(String_Grade2.trim()))) {
        Error_Flag = 5;
        R_Value = true;
      }
      if (!(String_Grade3.equals(String_Grade3.trim()))) {
        Error_Flag = 5;
        R_Value = true;
      }

      // Once the flag is set, return to call the program.
      if (0 < Error_Flag) {
        return R_Value;
      }

      // Remove the white spaces
      String_Name = String_Name.trim();
      String_Grade1 = String_Grade1.trim();
      String_Grade2 = String_Grade2.trim();
      String_Grade3 = String_Grade3.trim();

      // Check for the empty names or null values
      if ((String_Name.equals("")) || (null == String_Name)) {
        Error_Flag = 4;
        R_Value = true;
      }

      if (0 < Error_Flag) {
        return R_Value;
      }

      // Make sure the name starts with a letter.
      if (!((String_Name.equals("")) || (null == String_Name))) {
        int ASCII = Demo_String.charAt(0);

        if (ASCII < 65) {
          Error_Flag = 1;
          R_Value = true;
        } else if ((ASCII > 58) && (ASCII < 65)) {
          Error_Flag = 1;
          R_Value = true;
        } else if (ASCII > 122) {
          Error_Flag = 1;
          R_Value = true;
        }
      }

      if (0 < Error_Flag) {
        return R_Value;
      }

      // Check for empty grades or null values
      if ((String_Grade1.equals("")) || (null == String_Grade1)) {
        Error_Flag = 2;
        R_Value = true;
      } else if ((String_Grade2.equals("")) || (null == String_Grade2)) {
        Error_Flag = 2;
        R_Value = true;
      } else if ((String_Grade3.equals("")) || (null == String_Grade3)) {
        Error_Flag = 2;
        R_Value = true;
      }

      if (0 < Error_Flag) {
        return R_Value;
      }

      // Make sure the grades contain only numbers
      try {
        String_Grade_1 = Integer.parseInt(String_Grade1);
        String_Grade_2 = Integer.parseInt(String_Grade2);
        String_Grade_3 = Integer.parseInt(String_Grade3);
      } catch (NumberFormatException e) {
        R_Value = true;
      }

      // Make sure the grades have only three digits
      if (3 < String_Grade1.length()) {
        Error_Flag = 3;
        R_Value = true;
      } else if (3 < String_Grade2.length()) {
        Error_Flag = 3;
        R_Value = true;
      } else if (3 < String_Grade3.length()) {
        Error_Flag = 3;
        R_Value = true;
      }
    }

    return R_Value;
  }
}