用方法Java添加用户元素多维数组

Question

    public static void main(String[]args)
    {
        new Lab2();
    }

    public Lab2()
    {
        Scanner input = new Scanner(System.in);

        while(true)
        {
            System.out.println("Welcome to the Contact Directory, please select from following: ");
            System.out.println("Type 1 to add contact, 2 to remove contact, 3 to display contacts and 0 to exit.");
            int intChoice = input.nextInt();
            input.nextLine();

            String strFirstName; 
            String strLastName;
            switch(intChoice)
            {
                case 1:
                System.out.println("Enter First Name");
                strFirstName = input.nextLine();

                System.out.println("Enter Last Name");
                strLastName = input.nextLine();

                System.out.println("Enter Phone Number");
                String strPhoneNumber = input.nextLine();

                System.out.println("Enter Age");
                String strAge = input.nextLine();

                addItem(strFirstName, strLastName, strPhoneNumber, strAge);
                break;
                case 2:
                System.out.println("Enter First Name to Remove");
                strFirstName = input.nextLine();

                System.out.println("Enter Last Name to Remove");
                strLastName = input.nextLine();

                removeItem(strFirstName, strLastName);
                break;
                case3:// GETTING AN ERROR UNREACHABLE STATEMENT
                displayItems();
                break;
                case 0:
                System.exit(0);
            }
        }
    }

    public void addItem(String strFirstName, String strLastName,
    String strPhoneNumber, String strAge)
    {

       for(int i = 0; i < myArray.length; i++)
    {
        for(int j = 0; j < myArray[i].length; j++)
        {
           if (myArray[i][0] == null)
           {
               myArray[i][0] = strFirstName;
               myArray[i][1] = strLastName;
               myArray[i][2] = strPhoneNumber;
               myArray[i][3] = strAge;
               ; break;
            }
       }
    }
}

    public void removeItem(String strFirstName, String strLastName)
    {
         int i, j;

         for(i = 0; i < myArray.length; i++)
         {
             for(j = 0; j < myArray.length - 1; j++){
                     myArray[i][j] = myArray[i + 1][j];
                     break;
                }
            }
        }

    public void displayItems()
    { 
        for(int i = 0; i < myArray.length; i++)
        {
            for (int j = 0; j < myArray[i].length; j++)
            {
                System.out.print(myArray[i][j] + " ");
            }
            System.out.println();
        }
    }

Answer 1

你的提示应该是用来修复你的问题的代码。找到下一个可用的并添加它。

    if (myArray[i][0] == null)
    {
        myArray[i][0] = strFirstName;
        myArray[i][1] = strLastName;
        myArray[i][2] = strPhoneNumber;
        myArray[i][3] = strAge;
        blnInserted = true; 
        break;
    }

您不需要第二个循环，因为您只是根据名字检查整个条目是否null。在移除封闭的第二个循环后，代码应该添加到您感到困惑的部分。

此外，不需要在之后进行null检查。如果是null，您将无法检查相等性，因为这样做需要一个不能是null的实例。