Question

我基本上有一个程序可以从文件和文件中读取杂货。将它们存储在一个数组中。它允许用户添加项目（项目名称，项目数量）和从数组中删除项目。

但是，我在尝试编辑数组中的项目时遇到问题？因此，更改其名称和项目数。

以下是我的三个方法代码，用于添加，编辑（需要帮助）和删除：

/**
   * ADDS a grocery item to an array                          
   */
   public static Integer add(String [] list, Integer listSize){
      //get item from user
      Scanner keyboard = new Scanner(System.in);
      System.out.print("Enter name of item: ");
      String name = keyboard.nextLine();
      System.out.print("Enter number of items: ");
      String number = keyboard.nextLine();        
      //add to the end of the array
      list[listSize] = name + ", " + number;
      //add one to the size (one item to end of list)
      return listSize + 1;
   }

   /**
   * EDITS a grocery item to an array
   *
   * My steps to take
   *1: Prompt user for row number to be replaced
   *2: name of new item
   *3: number of new items
   *4: error checking: If the user enters a row number 
   *   that does not exist in the list- display error message
   */
   public static Integer edit(String [] list, Integer listSize){
      Scanner userInput = new Scanner(System.in);
      System.out.print("Enter the row number of the item you would like to edit: ");
      try{
         Integer row = userInput.nextInt();
         if(row <= 0){
            System.out.println("ERROR: The number can't be negative or zero!");
         }
         //check if int is too large
         else if(row > listSize-1){
            System.out.println("ERROR: The number is too big for the list.");
         }
         else{
            for(int i=row; i<listSize; i++){
               list[i] = list[i+1];
            } 
         }
         System.out.print("Enter name of item: ");
         String name = userInput.nextLine();
         System.out.print("Enter number of items: ");
         String number = userInput.nextLine();
         list[listSize] = name + ", " + number; 
      }
      catch(InputMismatchException exception){
         System.out.println("ERROR: You must enter a number to edit an item.");
      }
      return listSize ;
   }


   /**
   * DELETES a grocery item from an array                           
   */
   public static Integer delete(String [] list, Integer listSize){
       //get user input
      System.out.print("Enter the row number of the item you wish to delete: ");
      Scanner keyboard = new Scanner(System.in);
      try{
         //throws an exception if not an integer
         Integer row = keyboard.nextInt();
         //check for negative integers
         if(row <= 0){
            System.out.println("ERROR: The integer cannot be negative or zero.");
         }
            //check for integer too big
         else if(row > listSize-1){
            System.out.println("ERROR: The integer is too big for the list.");
         }
         else{
            //delete item by shifting items on the right of the item to the left
            for(int i=row;i<listSize;i++){
               list[i] = list[i+1];
            }
            //subtract one from the size (one item deleted from list)
            --listSize;
         }
      }
      catch(InputMismatchException exception){
         System.out.println("ERROR: You must enter an integer to delete an item.");
      }
      return listSize ;
   }

非常感谢任何帮助：o！

Answer 1

这不是你的问题吗？

list[listSize] = name + ", " + number;

应该是：

list[row] = name + ", " + number;

此外，你应该不拥有for循环：

for(int i=row; i<listSize; i++){
   list[i] = list[i+1];
}

下次请列出您的所有问题，而不是让我们找到它们。

Answer 2

你的'编辑'方法应该是：

public static Integer edit(String [] list, Integer listSize){
    Scanner userInput = new Scanner(System.in);
    System.out.print("Enter the row number of the item you would like to edit: ");
    try{
        Integer row = userInput.nextInt();
        if(row <= 0){
            System.out.println("ERROR: The number can't be negative or zero!");
        }
        //check if int is too large
        else if(row > listSize-1){
            System.out.println("ERROR: The number is too big for the list.");
        }
        else{
            /*
            for(int i=row; i<listSize; i++){
                list[i] = list[i+1];
            } 
            */
        }
        System.out.print("Enter name of item: ");
        String name = userInput.nextLine();
        System.out.print("Enter number of items: ");
        String number = userInput.nextLine();
        //list[listSize] = name + ", " + number; 
        list[row] = name + ", " + number; 
    }
    catch(InputMismatchException exception){
        System.out.println("ERROR: You must enter a number to edit an item.");
    }
    return listSize ;
}

如何编辑数组中的项目？

2 个答案: