使用带有菜单方法的 Java arraylist

Question

此代码有 2 个问题：我该如何编码，以便在用户添加到数组列表后 'theFruit' 如果他们然后按 'V' 查看所有水果，它包括默认水果以及他们添加的水果？

同样在方法'AddFruit'中它只允许我在打印前添加2个水果。为什么是这样？提前谢谢你

import java.util.ArrayList;
import java.util.Scanner;

public class StkOv {
public static void main(String[] args) {

     TheMenu();

 }

public static void TheMenu()
{


         String Customer[] = new String[10]; 

     Scanner input = new Scanner(System.in);

          String option; 
          do {   // loop back to here as long as Q isn't selected           
              System.out.println("\nMenu");
              System.out.println("V: Views all fruit");
              System.out.println("A: To add a fruit to the list");
          System.out.println("Q: To exit");

          option = input.next();  

          if (option.charAt(0) == 'V' ) 
          { 
              viewAllFruit(Customer);
              } 


          if (option.charAt(0) == 'A' ) 
          { 
              AddFruit(Customer);
          }

          }
          while (option.charAt(0) != 'Q');

          }


    public static void viewAllFruit(String CustomerRef[])
    {
        ArrayList<String> theFruit = new ArrayList<String>();

        theFruit.add("Plums");
        theFruit.add("Grapes");
        theFruit.add("Oranges");
        theFruit.add("Prunes");
        theFruit.add("Apples");

         int size = theFruit.size();
        for (int x = 0; x<size; x++) //for loop for fruits
        {            
            System.out.println("Fruit " + x + " is in stock " + theFruit);   
        }
        }

public static void AddFruit(String CustomerRef[])

{

    Scanner input = new Scanner(System.in);

    ArrayList<String> theFruit = new ArrayList<String>();

    theFruit.add("Plums");
    theFruit.add("Grapes");
    theFruit.add("Oranges");
    theFruit.add("Prunes");
    theFruit.add("Apples");

    System.out.println("Enter the fruits you'd like to add and EE to exit");
    String choice = input.next();

    String EE = "Goodbye!";

    if (choice !=EE);
    {
        theFruit.add(choice);
        choice = input.next();

    }

    for (String S : theFruit)

    {
        System.out.println(S);
    }


}
}

Answer 1

可能不止两个:)

你的水果列表应该在你的程序中"global"，这样它的内容就可以被viewAllFruit打印出来，新的水果可以在addFruit方法中添加。

就像现在一样，在创建新列表的两种方法中，向其中添加 "defualt" 水果，然后打印内容。当用户输入其选择时，您将再次创建这些列表。

记住 永远不要用 == 或 != 比较字符串，总是用 equals()

下面是您的代码的一些 "cleaner" 版本。

public static void List<String> initFruits() {
    ArrayList<String> theFruit = new ArrayList<String>();
    theFruit.add("Plums");
    theFruit.add("Grapes");
    theFruit.add("Oranges");
    theFruit.add("Prunes");
    theFruit.add("Apples");
    return theFruit;
}

public static void viewAllFruit(List<String> fruits,String CustomerRef[])
{
    for (String fruit : fruits) {
        System.out.println("Fruit " + fruit + " is in stock ");   
    }
}

public static void addFruit(List<String> fruits,String CustomerRef[])
{

    Scanner input = new Scanner(System.in);
    String EE = "EE"; //you assked for EE as quit but you wanted to compare with "Goodbye!";

    while(true) {
        System.out.println("Enter the fruits you'd like to add and EE to exit");
        String choice = input.next();


        if (choice.equals(EE)) {
           break;
        };

        fruits.add(choice);
    }
}

public static void TheMenu()
{
    String Customer[] = new String[10]; 

    Scanner input = new Scanner(System.in);
    List<String> fruits = initFruits();


    String option; 
    do {   // loop back to here as long as Q isn't selected           
    System.out.println("\nMenu");
    System.out.println("V: Views all fruit");
    System.out.println("A: To add a fruit to the list");
    System.out.println("Q: To exit");

    option = input.next();  

    if (option.charAt(0) == 'V' ) 
    { 
        viewAllFruit(fruits,Customer);
    } 


    if (option.charAt(0) == 'A' ) 
    { 
        addFruit(fruits,Customer);
    }

    }
    while (option.charAt(0) != 'Q');

}

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