Question

使用数据数组，创建书籍实例并将其存储在Book的一维数组中，称为bookArray。使用数量数组，浏览书籍数组并计算每本书销售的总费用。在对话框中打印书名，书籍以及每本书的总费用。然后，打印出售的所有书籍的总数。

到目前为止，我已经完成了此操作，但我遇到了JOptionPane和格式问题。

错误

$ javac BookTest.java
BookTest.java:41: error: incompatible types: String cannot be converted to String[][]
        dataArray +=String.format(" %s, %s ", b.getTitle(), b.getIsbn());
                                 ^
1 error

代码：

import javax.swing.JOptionPane;

public class BookTest { 
   public static void main(String args[]) {
      String dataArray  [][]=
         {{ "Fiction", "Abraham Lincoln Vampire Hunter", "Grahame-Smith", "Wiley", "NY", "978-0446563079", "13.99", "222"},
          {"Fiction", "Frankenstein", "Shelley", "Prescott", "GA", "978-0486282114", "7.99", "321"},
          {"NonFiction", "Life of Kennedy", "Jones", "Pearson", "MT", "758-29304566", "12.90", "biography"},
          {"Fiction", "Dracula", "Stoker", "Addison", "CA", "978-0486411095","5.99", "145"},
          {"Fiction", "Curse of the Wolfman", "Hageman", "Wesley", "MA", "B00381AKHG", "10.59", "876"},
          {"NonFiction", "How to Pass Java", "Willis", "Wiley"," NY", "444-395869790", "1.99", "technology"},
          {"Fiction", "The Mummy", "Rice", "Addision", "CA", "978-0345369949", "7.99", "954"},
          {"NonFiction", "History of Texas", "Smith", "Prescott", "CA", "123-683947687", "9.75", "history"}
         };

      Book bookArray[] = new Book [8];

      for (int i = 0; i < bookArray.length; i++) {
         if (dataArray[i][0].equals("Fiction")) {
            Publisher p = new Publisher(dataArray[i][3], dataArray[i][4]);
            bookArray[i] = new Fiction(dataArray[i][1], dataArray[i][2], dataArray[i][5],
               p, Double.parseDouble(dataArray[i][6]), dataArray[i][7]);
         } else {
            Publisher p = new Publisher(dataArray[i][3], dataArray[i][4]);
            bookArray[i] = new NonFiction(dataArray[i][1], dataArray[i][2], dataArray[i][5],
               p, Double.parseDouble(dataArray[i][6]), dataArray[i][7]);
         }
      }

      for (Book b:bookArray) {
        dataArray +=String.format(" %s, %s ", b.getTitle(), b.getIsbn());
        JOptionPane.showMessageDialog(null, dataArray);     
      }
   }        
}

Answer 1

String.format根据文档返回String。您正在尝试将String连接到2d数组。

dataArray +=String.format(" %s, %s ", b.getTitle(), b.getIsbn());

在上面的行中，您可能希望从2d数组访问某个位置，例如dataArray[0][0]，然后进行连接。类似的东西：

dataArray[0][0] +=String.format(" %s, %s ", b.getTitle(), b.getIsbn());

Answer 2

请勿使用dataArray输出消息框中的内容。使用 String 变量。

for (Book b : bookArray) {
    String bookOutput = String.format(" %s, %s ", b.getTitle(), b.getIsbn());
    JOptionPane.showMessageDialog(null, bookOutput);
}

更好，将toString()添加到返回Book的{{1}}类中，然后按此进行循环：

String.format(" %s, %s ", getTitle(), getIsbn())

然而，如果您想输出每本书的价格，然后输出总价，那么您的循环将更像 this ：

for (Book b : bookArray) {
    JOptionPane.showMessageDialog(null, b.toString());
}

格式化：字符串无法转换为String []

2 个答案: