Java：给定参数时选择对象

Question

我是一名初级 Java 程序员

现在我遇到了这个问题： 我有一个名为 Producttype 的类，其中包含一个名为 name 的字段。 我还有一个名为 Main 的类。现在，在类 Main 中，我想通过询问名称从类 Producttype 中选择一个对象。

我该怎么做？

提前感谢

Producttype 的代码：

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

public class Producttype
{
    //velden
    private String naam;
    private String beschrijving;
    private double aankoopprijs;
    private double verkoopprijs;
    private int aantalGekocht;
    private int aantalVerkocht;

    //constructor
    /**
     * Constructor
     */
    public Producttype(String naam, String beschrijving, double aankoopprijs, double verkoopprijs){
        this.naam = naam;
        this.beschrijving = beschrijving;
        this.aankoopprijs = aankoopprijs;
        this.verkoopprijs = verkoopprijs;
        aantalGekocht = 0;
        aantalVerkocht = 0;
    }
   public void drukInfo(){
        System.out.println("-----------------------");
        System.out.println("Naam van het product: " + naam);
        System.out.println("Beschrijving van het product: " + beschrijving);
        System.out.println("Aankoopprijs: " + aankoopprijs + " euro");
        System.out.println("Verkoopprijs: " + verkoopprijs + " euro");
        System.out.println("Aantal gekocht: " + aantalGekocht + " stuks");
        System.out.println("Aantal verkocht: " + aantalVerkocht + " stuks");
        System.out.println("");
        System.out.println("Aantal stuks in stock: " + berekenAantalInStock());
        System.out.println("");
        System.out.println("Omzet momenteel: " + berekenOmzet() + " euro");
        System.out.println("Winst momenteel: " + berekenWinst() + " euro");
    }

在我的“Main”中，我得到了这个：

private void printInfoOverProducttype()
    {
        String type = JOptionPane.showInputDialog("Give the name of the producctype you want info of.");

        String info = ??????????????????????????

        System.out.println(info);
    }

我想要的是方法 printInforOverProducctype() 中的“String info”从名称所在的对象的类“Producctype”中执行方法 drukInfo()等于字符串类型

Answer 1

您的 Main 类需要能够访问 ProductType 的 Map，其中键是名称 String：

public class Main {
    private Map<String, ProductType> products = new ConcurrentHashMap<String, ProductType>();

    public ProductType findProductTypeByName(String name) {
        return this.products.get(name);
    }
}