Java 2

Week 2

Topic this Week

CSV file input
Streams
Functional Interfaces
Method References

BPA State Competition

Open the 2024 Java competition file.
Open VS Code. Close your project from last week.
From page 3: "Create a folder on the flash drive provided using your contestant number as the name of the folder"
- Create a new Java project with no build tools.
- Title it "JAVA-KNNNNNNN"
From page 3: "Copy your entire solution/project into this folder. The project folder has already been provided for you : Java_State"
- Delete the App.java file.
- Download this file and place it in the src folder.
Please note that the directions and starter code are created by a volunteer; don't get frustrated with typos.
Read the remaining directions on pages 3-4 and rubric on page 9.
- The directions on pages 3-4 are consistent from year to year.
- Read the rubric on page 8 as you go.

Update Starter Code

Inspect the provided Java code. Note that only one class is declared public
Change the "Students" class to "Student". Rename the constructors. Update the class name on lines 39, 63, and 72.
- I think it will make the program easier to understand
Create a static List<Student> object in the SeatingChartBuilderState class.
Line 93 says, "Create appropriately variables based upon constructor parameters"
Update the parameterized constructor and getter methods.
Format the code by pressing Shift + Alt + F
You can make other adjustments like moving the Student class to a separate file, but it is not necessary.
Your code will look like the example on the next slide.
- This code includes the first 3 comments (See page 9).

/**
 * Contestant number: KNNNNNNN
 */
 
import java.io.FileNotFoundException;
import java.io.File;
import java.util.*;
import java.text.DecimalFormat;

public class SeatingChartBuilderState {

   //SC2 Create Scanner and ArrayList objects
   private static Scanner scanner = new Scanner(System.in);
   private static List<Student> students = new ArrayList<>();

   public static void main(String args[]) {

      inputManager();

      printStudents();
      printHighestGPA();
      printLowestGPA();

   }

   // Finds and prints the highest GPA from all the students
   private static void printHighestGPA() {

   }

   // Finds and prints the lowest GPA from all the students
   private static void printLowestGPA() {

   }

   private static void setStudents(int nc) {
      Random rand = new Random();
      Student s;
      DecimalFormat df = new DecimalFormat("#.00");
      int nameCount = nc;
      double gpa;
      int grade;
      String fn;
      String ln;

      String[] allNames = { "Walter", "Jones", "Rose", "Wilson", "Jack", "Rodriguez", "Elizabeth", "Smith", "Earl",
            "Carter", "Linda", "Ward", "Christopher",
            "Turner", "Martin", "Murphy", "Betty", "Garcia", "Shawn", "Taylor", "Sean", "Simmons", "Joshua", "Evans",
            "Norma", "Mitchell", "Brenda", "Johnson", "Donna",
            "Clark", "Irene", "Diaz", "Marilyn", "Coleman", "Arthur", "Collins", "Henry", "Hall", "Howard", "Robinson",
            "Jerry", "Green", "Maria", "Price", "Evelyn", "Bell",
            "Janet", "Moore", "Susan", "Foster" };

      for (int i = 0; i < nameCount; i++) {

         do {

            fn = allNames[rand.nextInt(allNames.length)];
            ln = allNames[rand.nextInt(allNames.length)];
         } while (fn.equals(ln));
         grade = rand.nextInt(4) + 9;
         double tempGPA = rand.nextDouble() * 3.0 + 1.0;
         String tempString = df.format(tempGPA);
         gpa = Double.parseDouble(tempString);
         s = new Student(fn, ln, grade, gpa);
         students.add(s);
      }

   }

   // Given
   private static void printStudents() {
      int i = 1;
      for (Student n : students) {
         System.out
               .println(i + ") " + n.getWholeName() + " | Grade Level: " + n.getGradeLevel() + " | GPA: " + n.getGPA());
         i++;
      }

      printHighestGPA();
      printLowestGPA();
   }

   // Gets user input commands and checks for entry errors
   private static void inputManager() {

   }

}

//SC1 All constructors, methods, and variables are appropriately created.
class Student {
   // Create appropriately variables based upon constructor parameters
   private String firstName;
   private String lastName;
   private int gradeLevel;
   private double gpa;

   // Generic Constructor
   public Student() {

   }

   // Constructor with Parameters
   public Student(String fn, String ln, int gl, double gpa) {
      this.firstName = fn;
      this.lastName = ln;
      this.gradeLevel = gl;
      this.gpa = gpa;
   }

   // Returns "last name, first name" with appropriate variables
   public String getWholeName() {
      return String.format("%s, %s", lastName, firstName);
   }

   // Returns first name
   public String getFirstName() {
      return firstName;
   }

   // Returns last name
   public String getLastName() {
      return lastName;
   }

   // Returns the GPA
   public double getGPA() {
      return gpa;
   }

   // Returns grade level
   public int getGradeLevel() {
      return gradeLevel;
   }

}

Input Option 1, Step 1

This project is a menu-based program, similar to the final project in Java 1.
- See project_demo and shared packages.
- You can use this code during class assignments, but you will not be able to use that code during the state competition.
Read the directions starting on page 5. Do one step at a time.
For step 1, use the inputManager method. As you complete each step, I recommend completing the required error messages.
Try to make your output as close to the example as possible.
Add comments as you go.
Keep only the inputManager() function call in the main method or option 3 will cause an error.
Your code may look like the example on the next slide.
- What do you remember from Java 1?

// Gets user input commands and checks for entry errors
private static void inputManager() {
   Scanner scanner = new Scanner(System.in);
   loop: while(true) {
      System.out.println("\n---------------------------------------------------------------------");
      System.out.println("Hello. What would you like to do today?");
      System.out.println("Press [1] to create random students OR Press [2] to create a single student OR Press [3] to end the program");
      int choice = 0;
      // SC5 Code with try/catch exception for invalid data error
      try {
         choice = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }
	
      switch(choice) {
         case 1:
            break;
         case 2:
            break;
         case 3:
            break loop;
         default:
            // SC5 Code for range violation
            System.out.println("Your entry is out of range.");
      }
   }
   System.out.println("Goodbye!");
}

Input Option 1, Step 2

Consider creating your own helper methods to organize your code.
Create a method called step2 that has no inputs and returns an int.
Write code to handle the instructions and error messages.
Add comments as you go.
Your code may look like the example on the next slide.
- What do you remember from Java 1?
- In Java 1, we passed the Scanner object as an argument to helper methods. This is required if you split your project into multiple packages and files.

// Gets user input commands and checks for entry errors
private static void inputManager() {
   Scanner scanner = new Scanner(System.in);
   loop: while(true) {
      System.out.println("\n---------------------------------------------------------------------");
      System.out.println("Hello. What would you like to do today?");
      System.out.println("Press [1] to create random students OR Press [2] to create a single student OR Press [3] to end the program");
      int choice = 0;
      // SC5 Code with try/catch exception for invalid data error
      try {
         choice = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }

      switch(choice) {
         case 1:
            int numStudentsToCreate = option1Step2();
            break;
         case 2:
            break;
         case 3:
            break loop;
         default:
            // SC5 Code with try/catch exception for invalid data error
            System.out.println("Your entry is out of range.");
      }
   }
   System.out.println("Goodbye!");
}

private static int option1Step2() {
   int val = 0;
   loop: while(true) {
      System.out.print("\nPlease enter in a value between 1 and 50: ");
      // SC6 Code with try/catch exception for invalid data error
      try {
         val = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }
      // SC6 Code for range violation
      if(val < 1 || val > 50) {
         System.out.println("Your entry is out of range.");
         continue;
      }
      break;
   }
   return val;
}

Input Option 1, Step 3

Create a new method called step3 that takes an int as input and returns void.
Use the value returned from the step 2 method when calling the step3 method.
Write code to handle the instructions. In situations like this, call methods that already exist.
Implement the printHighestGPA and printLowestGPA methods.
Add comments as you go.
Your code may look like the example on the next slide.
- What do you remember from Java 1?
- Later we will improve the methods that calculate the highest and lowest GPAs.
This is probably where I would expect most students to get in 90 minutes.

// SC3: Finds and prints the highest GPA from all the students
private static void printHighestGPA() {
   Student highestGPA = students.get(0);
   for(Student student: students) {
      if(student.getGPA() > highestGPA.getGPA()) {
         highestGPA = student;
      }
   }
   System.out.printf("\n\nMax GPA: %.2f %s, %s\n", highestGPA.getGPA(), highestGPA.getLastName(), highestGPA.getFirstName());
}

// SC4: Finds and prints the lowest GPA from all the students
private static void printLowestGPA() {
   Student lowestGPA = students.get(0);
   for(Student student: students) {
      if(student.getGPA() < lowestGPA.getGPA()) {
         lowestGPA = student;
      }
   }
   System.out.printf("\n\nMin GPA: %.2f %s, %s\n", lowestGPA.getGPA(), lowestGPA.getLastName(), lowestGPA.getFirstName());
}

// Gets user input commands and checks for entry errors
private static void inputManager() {
   Scanner scanner = new Scanner(System.in);
   loop: while(true) {
      System.out.println("\n---------------------------------------------------------------------");
      System.out.println("Hello. What would you like to do today?");
      System.out.println("Press [1] to create random students OR Press [2] to create a single student OR Press [3] to end the program");
      int choice = 0;
      try {
         choice = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }

      switch(choice) {
         case 1:
            int numStudentsToCreate = option1Step2(scanner);
            option1Step3(numStudentsToCreate);
            break;
         case 2:
            break;
         case 3:
            break loop;
         default:
            System.out.println("Your entry is out of range.");
      }
   }
   System.out.println("Goodbye!");
}

private static void option1Step3(int numStudentsToCreate) {
   setStudents(numStudentsToCreate);
   printStudents();
}

Input Option 2, Steps 2-6

Create a method to create a new student.
Getting the first name and last name require no validation
Getting the gradeLevel and gpa require validation.
Add the newly created object to your List. Print the list.
Add a line before printing the student list.
Your code may look like the example on the next slide.

private static void printStudents() {
   int i = 1;
   System.out.println("\n---------------------------------------------------------------------");
   for (Student n : students) {
      System.out
            .println(i + ") " + n.getWholeName() + " | Grade Level: " + n.getGradeLevel() + " | GPA: " + n.getGPA());
      i++;
   }

   printHighestGPA();
   printLowestGPA();
}

// Gets user input commands and checks for entry errors
private static void inputManager() {
   loop: while(true) {
      System.out.println("\n---------------------------------------------------------------------");
      System.out.println("Hello. What would you like to do today?");
      System.out.println("Press [1] to create random students OR Press [2] to create a single student OR Press [3] to end the program");
      int choice = 0;
      // SC5 Code with try/catch exception for invalid data error
      try {
         choice = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }

      switch(choice) {
         case 1:
            int numStudentsToCreate = option1Step2(scanner);
            option1Step3(numStudentsToCreate);
            break;
         case 2:
            createSingleStudent();
            break;
         case 3:
            break loop;
         default:
            // SC5 Code for range violation
            System.out.println("Your entry is out of range.");
      }
   }
   System.out.println("Goodbye!");
}

private static void createSingleStudent() {
   System.out.println("You are now creating a single student");
   // Option 2, Step 2
   System.out.println("Enter in the first name");
   String firstName = scanner.nextLine();
   // Option 2, Step 3
   System.out.println("Enter in the last name");
   String lastName = scanner.nextLine();
   // Option 2, Step 4
   int gradeLevel = option2Step4();
   // Option 2, Step 5
   double gpa = option2Step5();
   students.add(new Student(firstName, lastName, gradeLevel, gpa));
   printStudents();
}

private static double option2Step5() {
   double gpa = 0;
   while(true) {
      System.out.println("Enter in the GPA in its proper format (#.##)");
      try {
         gpa = scanner.nextDouble();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }
      if(gpa < 0 || gpa > 4) {
         System.out.println("Your entry is out of range.");
         continue;
      }
      break;
   }
   return gpa;
}

private static int option2Step4() {
   int gradeLevel = 0;
   while(true) {
      System.out.println("Enter in the student grade level");
      try {
         gradeLevel = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }
      if(gradeLevel < 9 || gradeLevel > 12) {
         System.out.println("Your entry is out of range.");
         continue;
      }
      break;
   }
   return gradeLevel;
}

Completed Code

// Contestant: K0519415

import java.io.FileNotFoundException;
import java.io.File;
import java.util.*;
import java.text.DecimalFormat;

public class SeatingChartBuilderState {

   // SC2: Create Scanner and ArrayList objects
   private static Scanner scanner = new Scanner(System.in);
   private static List<Students> students = new ArrayList<>();

   public static void main(String args[]) {
      inputManager();
   }


   // SC3: Finds and prints the highest GPA from all the students
   private static void printHighestGPA() {
      if(students.size() == 0) {
         return;
      }
      // Students highest = students.get(0);
      // for(Students student: students) {
      //    if(student.getGPA() > highest.getGPA()) {
      //       highest = student;
      //    }
      // }
      Students highest = students.stream().max(Comparator.comparingDouble(Students::getGPA)).get();
      System.out.println("\n\nMax GPA: " + highest.getGPAStr() + " " + highest.getWholeName());
   }

   // SC4: Finds and prints the lowest GPA from all the students
   private static void printLowestGPA() {
      if(students.size() == 0) {
         return;
      }
      // Students lowest = students.get(0);
      // for(Students student: students) {
      //    if(student.getGPA() < lowest.getGPA()) {
      //       lowest = student;
      //    }
      // }
      Students lowest = students.stream().min(Comparator.comparingDouble(Students::getGPA)).get();
      System.out.println("\n\nMin GPA: " + lowest.getGPAStr() + " " + lowest.getWholeName());
   }

   // Call this method to generate a random list of students
   private static void setStudents(int nc) {
      Random rand = new Random();
      Students s;
      DecimalFormat df = new DecimalFormat("#.00");
      int nameCount = nc;
      double gpa;
      int grade;
      String fn;
      String ln;

      String[] allNames = {"Walter", "Jones", "Rose", "Wilson", "Jack", "Rodriguez", "Elizabeth",
            "Smith", "Earl", "Carter", "Linda", "Ward", "Christopher", "Turner", "Martin", "Murphy",
            "Betty", "Garcia", "Shawn", "Taylor", "Sean", "Simmons", "Joshua", "Evans", "Norma",
            "Mitchell", "Brenda", "Johnson", "Donna", "Clark", "Irene", "Diaz", "Marilyn",
            "Coleman", "Arthur", "Collins", "Henry", "Hall", "Howard", "Robinson", "Jerry", "Green",
            "Maria", "Price", "Evelyn", "Bell", "Janet", "Moore", "Susan", "Foster"};

      for (int i = 0; i < nameCount; i++) {

         do {

            fn = allNames[rand.nextInt(allNames.length)];
            ln = allNames[rand.nextInt(allNames.length)];
         } while (fn.equals(ln));
         grade = rand.nextInt(4) + 9;
         double tempGPA = rand.nextDouble() * 3.0 + 1.0;
         String tempString = df.format(tempGPA);
         gpa = Double.parseDouble(tempString);
         s = new Students(fn, ln, grade, gpa);
         students.add(s);
      }

   }

   // Given
   private static void printStudents() {
      int i = 1;
      System.out.println("\n---------------------------------------------------------------------");
      for (Students n : students) {
         System.out.println(i + ") " + n.getWholeName() + " | Grade Level: " + n.getGradeLevel()
               + " | GPA: " + n.getGPAStr());
         i++;
      }

      printHighestGPA();
      printLowestGPA();
   }

   // Gets user input commands and checks for entry errors
   private static void inputManager() {
      loop: while(true) {
         System.out.println("\n---------------------------------------------------------------------");
         System.out.println("Hello. What would you like to do today?");
         System.out.println("Press [1] to create random students OR Press [2] to create a single student OR Press [3] to end the program");
         int choice = 0;
         // SC5: Code with try/catch exception for invalid data error
         try {
            choice = scanner.nextInt();
         } catch(InputMismatchException e) {
            System.out.println("ERROR: Please enter valid data type");
            continue;
         } finally {
            scanner.nextLine();
         }
      
         switch(choice) {
            case 1:
               int numStudents = option1Step2();
               setStudents(numStudents);
               printStudents();
               break;
            case 2:
               createSingleStudent();
               break;
            case 3:
               // SC11: Code that exits the program
               break loop;
            default:
               // SC5 Code for range violation
               System.out.println("Your entry is out of range.");
         }
      }
      System.out.println("Goodbye!");
   }

   private static void createSingleStudent() {
      System.out.println("You are now creating a single student");
      // Option 2, Step 2
      System.out.println("Enter in the first name");
      String firstName = scanner.nextLine();
      // Option 2, Step 3
      System.out.println("Enter in the last name");
      String lastName = scanner.nextLine();
      // Option 2, Step 4
      int gradeLevel = option2Step4();
      // Option 2, Step 5
      double gpa = option2Step5();
      students.add(new Students(firstName, lastName, gradeLevel, gpa));
      printStudents();
   }
    
   private static double option2Step5() {
      double gpa = 0;
      while(true) {
         System.out.println("Enter in the GPA in its proper format (#.##)");
         // SC8: Code try-catch for invalid data
         try {
            gpa = scanner.nextDouble();
         } catch(InputMismatchException e) {
            System.out.println("ERROR: Please enter valid data type");
            continue;
         } finally {
            scanner.nextLine();
         }
         // SC8: Code range violation
         if(gpa < 0 || gpa > 4) {
            System.out.println("Your entry is out of range.");
            continue;
         }
         break;
      }
      return gpa;
   }
    
   private static int option2Step4() {
      int gradeLevel = 0;
      while(true) {
         System.out.println("Enter in the student grade level");
         // SC7: Code try-catch for invalid data
         try {
            gradeLevel = scanner.nextInt();
         } catch(InputMismatchException e) {
            System.out.println("ERROR: Please enter valid data type");
            continue;
         } finally {
            scanner.nextLine();
         }
         // SC7: Code for range violation
         if(gradeLevel < 9 || gradeLevel > 12) {
            System.out.println("Your entry is out of range.");
            continue;
         }
         break;
      }
      return gradeLevel;
   }

   	
private static int option1Step2() {
   int val = 0;
   loop: while(true) {
      System.out.print("\nPlease enter in a value between 1 and 50: ");
      // SC6 Code with try/catch exception for invalid data error
      try {
         val = scanner.nextInt();
      } catch(InputMismatchException e) {
         System.out.println("ERROR: Please enter valid data type");
         continue;
      } finally {
         scanner.nextLine();
      }
      // SC6 Code for range violation
      if(val < 1 || val > 50) {
         System.out.println("Your entry is out of range.");
         continue;
      }
      break;
   }
   return val;
}




}


// SC1: All constructors, methods, and variables are appropriately created.
class Students {
   // Create appropriately variables based upon constructor parameters
   private String firstName;
   private String lastName;
   private int gradeLevel;
   private double gpa;

   // Generic Constructor
   public Students() {

   }

   // Constructor with Parameters
   public Students(String firstName, String lastName, int gradeLevel, double gpa) {
      this.firstName = firstName;
      this.lastName = lastName;
      this.gradeLevel = gradeLevel;
      this.gpa = gpa;
   }

   // SC10: Returns "last name, first name" with required convention
   public String getWholeName() {
      return String.format("%s%s, %s%s", 
      lastName.substring(0, 1).toUpperCase(), 
      lastName.substring(1).toLowerCase(),  
      firstName.substring(0, 1).toUpperCase(),
      firstName.substring(1).toLowerCase());
   }



   // Returns first name
   public String getFirstName() {
      return firstName;
   }

   // Returns last name
   public String getLastName() {
      return lastName;
   }

   // Returns the GPA
   public double getGPA() {
      return gpa;
   }

   // SC9: Returns the GPA formatted with proper DecimalFormat object
   public String getGPAStr() {
      DecimalFormat df = new DecimalFormat("#.00");
      return df.format(gpa);
   }

   // Returns grade level
   public int getGradeLevel() {
      return gradeLevel;
   }



}

What is CSV?

CSV (comma-separated values) files are a standard data text storage format.
They are easy to edit in any text editor or spreadsheet software.
Download this CSV file and save it in the root directory of your project folder.
The first line is an optional heading row. It contains attribute names.
Each field (column) is separated by a comma, called a delimiter.
The delimiter can also be a tab (TSV) any other character.
All other lines are individual data records.
Records should represent one type of entity.
Click the Download button at the bottom of this page to see a more complex example.

President Class

Using the first line header row, create a President class with 6 attributes

import java.time.LocalDate;

public class President {
    private int id;
    private String firstName;
    private String lastName;
    private int heightInInches;
    private double weightInPounds;
    private LocalDate dateOfBirth;

    public President() {}

    public President(int id, String firstName, String lastName, int heightInInches, double weightInPounds,
            LocalDate dateOfBirth) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.heightInInches = heightInInches;
        this.weightInPounds = weightInPounds;
        this.dateOfBirth = dateOfBirth;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public int getHeightInInches() {
        return heightInInches;
    }

    public void setHeightInInches(int heightInInches) {
        this.heightInInches = heightInInches;
    }

    public double getWeightInPounds() {
        return weightInPounds;
    }

    public void setWeightInPounds(double weightInPounds) {
        this.weightInPounds = weightInPounds;
    }

    public LocalDate getDateOfBirth() {
        return dateOfBirth;
    }

    public void setDateOfBirth(LocalDate dateOfBirth) {
        this.dateOfBirth = dateOfBirth;
    }

    @Override
    public String toString() {
        return "President [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", heightInInches="
                + heightInInches + ", weightInPounds=" + weightInPounds + ", dateOfBirth=" + dateOfBirth + "]";
    }
    
}

FileInput Class

Create a class to read all lines or a single line from a file.
Per this page, don't use Scanner object if you want to read the file line by line

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

public class FileInput {
    private static String pathToFiles = "src/";

    public static List<String> readAllLines(String filename) {
        List<String> lines = null;
        try {
            lines = Files.readAllLines(Paths.get(pathToFiles + filename));
        } 
        // try(Scanner scanner = new Scanner(new File(pathToFiles + filename))) {
        //     lines = new ArrayList<>();
        //     while(scanner.hasNextLine()) {
        //         lines.add(scanner.nextLine());
        //     }
        // } 
        catch (IOException e) {
            System.out.println("The " + filename + " file doesn't exist.");
            System.exit(0);
        }
        return lines;
    }

    public static String readFirstLine(String filename) {
        String line = "";
        try(Scanner scanner = new Scanner(new File(pathToFiles + filename))) {
            line = scanner.nextLine();
        } catch (FileNotFoundException e) {
            System.out.println("Error reading file " + filename + ".");
            System.exit(0);
        } catch (NoSuchElementException e) {
            System.out.println("Cannot read line from " + filename + ".");
            System.exit(0);
        }
        return line;
    }

    public static void main(String[] args) {
        List<String> lines = readAllLines("presidents.csv");
        lines.forEach(System.out::println);
        String line = readFirstLine("presidents.csv");
        System.out.println(line);
    }

}

PresidentDAO Class

Create a class that is used to convert lines from the text file to objects.
Create a method to read data from a data file.

import java.time.LocalDate;
import java.time.format.DateTimeParseException;
import java.util.ArrayList;
import java.util.List;


public class PresidentDAO {
    private static List<President> presidents = new ArrayList<>();
    
    public static void main(String[] args) {
        getPresidents().forEach(System.out::println);
    }

    public static List<President> getPresidents() {
        if(presidents.size() == 0) {
             getFromCSV();
        }
        return presidents;
    }

    private static void getFromCSV() {
        List<String> lines = FileInput.readAllLines("presidents.csv");
        for(String line: lines) {
            String[] president = line.split(",");
            try {
                int id = Integer.parseInt(president[0].trim());
                String firstName = president[1].trim();
                String lastName = president[2].trim();
                int height = Integer.parseInt(president[3].trim());
                double weight = Double.parseDouble(president[4].trim());
                LocalDate dateOfBirth = LocalDate.parse(president[5].trim());
                presidents.add(new President(id, firstName, lastName, height, weight, dateOfBirth));
            } catch(IndexOutOfBoundsException | NumberFormatException | DateTimeParseException e) {
                // Skip the line if it is missing a field, or if the String cannot be converted into an int, double, or LocalDate.
                continue;
            }
        }
    }
    
}

CSV Libraries

https://www.baeldung.com/apache-commons-csv
https://github.com/super-csv/super-csv
https://super-csv.github.io/super-csv/index.html
https://github.com/42BV/CSVeed
https://42bv.github.io/CSVeed/csveed.html
https://opencsv.sourceforge.net/
https://www.baeldung.com/opencsv
https://jenkov.com/tutorials/java-io/bufferedoutputstream.html

Java 2 - Week 2

By Marc Hauschildt

Java 2 - Week 2

Marc Hauschildt

Web Technologies and Computer Software Development Instructor at Kirkwood Community College in Cedar Rapids, IA.

kirkwood.edu/businessit

Java 2

Topic this Week

BPA State Competition

Update Starter Code

Input Option 1, Step 1

Input Option 1, Step 2

Input Option 1, Step 3

Input Option 2, Steps 2-6

Completed Code

What is CSV?

President Class

FileInput Class

PresidentDAO Class

CSV Libraries

Java 2 - Week 2

More from Marc Hauschildt