如何在不使用 getter 和 setter 的情况下显示另一个 class 的变量？

Question

I'm a first-year student and I'm really struggling here. This is one of the questions that I have to do for my Assignment (I am allowed to use StackOverflow for guidance).

Create a class named Customer that will determine the monthly repayment amount due by a customer for a product bought on credit. The class has five fields: customer name , contact number , product price , number of months , and the monthly repayment amount .

Write get and set methods for each field, except for the monthly repayment amount field. The set methods must prompt the user to enter the values for the following fields: customer name , contact number , product price , and a number of months .

This class also needs a method to calculate the monthly repayment amount (product price divided by the number of months).

Add a subclass named Finance_Period that will determine if a customer will pay interest or not.

If the number of months to pay for the product is greater than three, the customer will pay 25% interest, or else no interest applies.

The maximum number of months to pay for the product is 12.

Override the calculate_repayment() method by determining if the customer will pay interest or not and calculate the monthly repayment amount.

Create a class called Customer_Finance that contains the logic to test the two classes.

Prompt the user for data for the first object where no interest applies and display the results; then prompt the user for data where interest is applicable and displays the results.

I'm struggling to call amtRepay into my main without using getters and setters .

I'm not even sure if I understand the question correctly, any guidance or advice would be greatly appreciated.

Also, I have another class called Finace_Period , there is nothing there yet, I'm not 100% sure of what I'm doing yet.

This is my main class, where I want to display amtRepay .

package main;

import javax.swing.JOptionPane;


public class Main {

    
    public static void main(String[] args) {
        //Variables
        String name;
        int cNumber, months;
        double price;
        
        //Input
        name = JOptionPane.showInputDialog(null, "Please enter the customer's name:");
        cNumber = Integer.parseInt(JOptionPane.showInputDialog(null, "Please enter the customer's contact number:"));
        price = Double.parseDouble(JOptionPane.showInputDialog(null, "Please enter the price of the product:"));
        months = Integer.parseInt(JOptionPane.showInputDialog(null, "Please enter the number of repayment months:"));
        
        Customer c = new Customer(name, cNumber, months, price);
        
        JOptionPane.showMessageDialog(null, c.calcaAmtRepay());
                  
        }
    
    }

and this is my secondary class, where amtRepay is calculated.

package Main;

public class Customer extends Finance_Period {
    
    //Atributes
    private String name;
    private int cNumber, months;
    private double price, amtRepay;
    
    //Constructors
    public Customer (String name, int cNumber, int months, double price) {
        this.name = name;
        this.cNumber = cNumber;
        this.months = months;
        this.price = price;
       
        
    }

    //Getters
    public String getName() {
        return name;
    }

    public int getcNumber() {
        return cNumber;
    }
    
    public int getMonths() {
        return months;
    }
    
     public double getPrice() {
        return price;
    }
     
    //Setter
    public void setName(String name) {
        this.name = name;
    }

    public void setcNumber(int cNumber) {
        this.cNumber = cNumber;
    }

    public void setMonths(int months) {
        this.months = months;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    //Calculation of monthly repayments
    public double calcAmtRepay () {
       
        amtRepay = price / months;
        
        return price / months;
    }
}

Thanks.

Answer 1

Change your constructor: leave the amtRepay argument.

//Constructors
public Customer (String name, int cNumber, int months, double price) {
    this.name = name;
    this.cNumber = cNumber;
    this.months = months;
    this.price = price;
}

Be aware that after the call to this constructor, the amtRepay field is still not calculated. Better: you don't even need the amtRepay field in Customer as its value is calculated each time you call calcAmtRepay() which is a good idea because otherwise you have to recalculate it also in setMonths and setPrice .

public double calcAmtRepay () {
    return price / months;    
}

JOptionPane.showMessageDialog(null, c.calcAmtRepay());

Answer 2

In your class main.Main you are referring to class main.Customer , but according to the code you posted you only have class Main.Customer .

Change package Main; to package main; in your Customer.java and it should work.

Edit:

I don't have Netbeans so I used Visual Studio Code with Java extensions installed.

I created an empty directory. Inside that directory I created file build.xml and subdirectory src . Inside src I created package main and copied your code. I also created empty class main.Finance_Period .

My IDE notified me that class main.Customer has method calcAmtRepay() , but in class main.Main you call calcaAmtRepay() - notice the additional, lowercase a between calc and Amt . I fixed that and then added the following to my build.xml :

<project name="MyProject" default="dist" basedir=".">
  <description>
    Java assignment build file
  </description>
  <!-- set global properties for this build -->
  <property name="src" location="src"/>
  <property name="build" location="build"/>
  <property name="dist" location="dist"/>

  <target name="init">
    <!-- Create the time stamp -->
    <tstamp/>
    <!-- Create the build directory structure used by compile -->
    <mkdir dir="${build}"/>
  </target>

  <target name="compile" depends="init"
        description="compile the source">
    <!-- Compile the Java code from ${src} into ${build} -->
    <javac srcdir="${src}" destdir="${build}"/>
  </target>

  <target name="dist" depends="compile"
        description="generate the distribution">
    <!-- Create the distribution directory -->
    <mkdir dir="${dist}/lib"/>

    <!-- Put everything in ${build} into the java-assignment-${DSTAMP}.jar file -->
    <jar jarfile="${dist}/lib/java-assignment-${DSTAMP}.jar" basedir="${build}"/>
  </target>

  <target name="clean"
        description="clean up">
    <!-- Delete the ${build} and ${dist} directory trees -->
    <delete dir="${build}"/>
    <delete dir="${dist}"/>
  </target>
</project>

Then I ran ant dist in the shell and finally executed:

java -cp dist/lib/java-assignment-20200901.jar main.Main

to run the application.

Both the compilation and the execution runs fine.

I used OpenJDK 11.0.8 2020-07-14.

Please let me know if any of this helps.

Edit 2:

I put the working code on GitLab . You can ignore the Dockerfile and references to Docker, the rest I already explained.