如何实现将文件加载到程序中的其他类可以使用的类？

Question

Okay so I am building a program that will sort grades and records of students. It is a command-line program and when run it will start by asking for user input. there are several commands such as exit(exits program), load [file name](loads a file name), student [student name] (loads student records), etc. the others are not important. Well basically what I am wondering and what I am stuck on is all those functions will be in separate classes and will be called when the user inputs a specific command, but if I put the "load" command in its own class, then how do I get it to share its information with the other classes? I know I have to use BufferReader to read in the files, but how would I go implementing my load class, or if there is a better way feel free to say so. here is my code so far. there isn't much on my other classes because I feel like I need to figure out how to read in and share the file with the other classes first.

import java.util.*;
import java.io.*;
public class program7
{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Grade Stats by ");
        System.out.print(">");
        while(scan.hasNextLine())
        {

            String input = scan.nextLine();

            if(input.equals("exit"))
            {
                System.exit(0);
            }
            else if(input.equals("help"))
            {
                System.out.println("exit                   - program closes.");
                System.out.println("load [filename]        - loads a class database specified in [filename].");
                System.out.println("students               - prints out a list of students from the class, along ");
                System.out.println("                         with total points, and final grades for each student.");
                System.out.println("assignments            - prints out a list of assignments from the file, along with points possible");
                System.out.println("student [student name] - Prints report for the student");
                System.out.print(">");
            }
            else if(input.contains("load"))
            {
                String[] split = input.split(" ");
                Load load = new Load(split[1]);
                System.out.print(">");
            }
            else if(input.equals("students"))
            {

                System.out.print(">");
            }
            else if(input.equals("assignments"))
            {

                System.out.print(">");
            }
            else if(input.contains("student"))
            {
                String[] split = input.split(" ");
                Student student = new Student(split[1]);
                System.out.print(">");
            }
            else if(input.contains("assignment")
            {

            }
            else if(input.equals("grades")
            {

            }
            else
            {
                System.out.println("exit                   - program closes.");
                System.out.println("load [filename]        - loads a class database specified in [filename].");
                System.out.println("students               - prints out a list of students from the class, along ");
                System.out.println("                         with total points, and final grades for each student.");
                System.out.println("assignments            - prints out a list of assignments from the file, along with points possible");
                System.out.println("student [student name] - Prints report for the student");
                System.out.print(">");
            }
        }
    }

}

that was my main class here are the function classes so far.

public class Load
{
    public Load()
    {
        BufferReader in = new BufferReader
    }

}




public class Student
{
    public Student()
    {

    }

}


import java.util.*;
import java.io.*;
public class Student
{

    private String student;
    public Student(inputFile
    public Student(String student)
    {
        this.student = student;
    }

    public String Splitter()
    {

    }
    public String Printer()
    {

    }

}

Answer 1

Well basically what I am wondering and what I am stuck on is all those functions will be in separate classes and will be called when the user inputs a specific command,

but if I put the "load" command in its own class, then how do I get it to share its information with the other classes?

If your Load class has a public getter method then you can retrieve it that way.

For example, with a method inside your Load class of

public String getFileContents() {
/* your BufferedFileReader and operations here */
    return s;
}

You can access it by making a Load object in your main class with

Load load = new Load();
String s = load.getFileContents();

This way you have made a String in your main program7 class and pulled the data from your Load class.

I hope this helps and has answered your question.

Can I access it in my other classes too, using the Load object? My other classes need some of the information because they process it differently. For example my students class, prints out the Students and their grades, while Student class will print out a certain student as specified by the user

So you might have a method in your Student class like

public void printGrades(String fileContents) {
    /* do stuff */
    System.out.println("Grades");
}

and then call it from your main program7 class by

Student student = new Student();
student.printGrades(s); // s is the String from load.getFileContents(); up above.

So you are passing the file contents from the Load class to the Student class through these public methods within each class.