BufferedReader在从CSV读取并分配给不同类型时跳过字段

Question

写入从CSV文件读取值的方法。我对BufferedReader没有太多的经验。在我使用的测试文件中有4列和50行。它应该读入并分配给4个变量（String category、String name、int quantity、BigDecimal price）,然后在我计算出读数后将这些变量传递给一个构造函数。我打印了这些值，看看我在哪里，但它们没有像预期的那样读入（见下文）。我想读两个字符串，然后是整数，最后是BigDecimal。它目前削减了一些字符和似乎跳过了其他，并没有打印新的行预期。

有谁能帮我弄明白是怎么回事吗？多谢了。

 public static void readFromFile(){
  BufferedReader fileReader = null;
  String csvFile = "/Users/Acer/Documents/CS1400/Assignments/InventoryApp/inventory.csv";
  int fileSize = 50; //input.nextInt;            

     try {
        fileReader = new BufferedReader(new FileReader(csvFile));
        for (int i = 0; i < fileSize; i++){
           String category = fileReader.readLine();                                    
           String name = fileReader.readLine();                 
           int quantity = fileReader.read();               
           BigDecimal price = new BigDecimal(fileReader.read());               
           System.out.println(category + " " + name + " " + quantity + " " + price);                                       
        }           
     }
     catch (IOException ioe) {
        System.out.println(ioe.getMessage());
     } finally {
        try {
        fileReader.close();
        }
        catch (IOException ioe) {
               System.out.println(ioe.getMessage());
        }
     } 
}   

电流输出：

Golf,Bag,7,49.99 Baseball,Baseball,4,12.99 72 111
ckey,Puck,8,11.99 Basketball,Basketball,2,15 70 111
otball,Football,7,13.95 Soccer,Ball,6,20.99 71 111
lf,Putter,2,65.5 Baseball,Catchers Mitt,9,49.99 72 111
ckey,Stick,2,27.99 Basketball,Shorts,4,20 70 111
otball,Shoulder Pads,8,34.99 Soccer,Goal,2,44.99 71 111
lf,Tees,4,2.99 Baseball,Cleats,8,50 72 111
ckey,Skates,3,69.99 Basketball,Hoop,5,99.99 70 111
otball,Cleats,2,67.99 Soccer,Shin Guards,4,35.95 71 111
lf,Balls,8,20 Baseball,Pants,5,34.98 72 111
ckey,Gear Bag,3,30 Basketball,Jersey,5,24.99 70 111
otball,Jersey,3,24.99 Soccer,Cleats,6,56.99 71 111
lf,Driver,8,99.99 Baseball,Bat Bag,9,40 72 111
ckey,Goal,9,30 Basketball,Socks,5,20 70 111
otball,Cup,9,12.95 Soccer,Socks,5,12 71 111
lf,3 Wood,2,80.99 Baseball,Socks,3,12.99 72 111
ckey,Neck Guard,2,1.99 Basketball,Catchers Mask,2,32.95 70 111
otball,Cup,7,12 Soccer,Cones,9,11.99 71 111
lf,Irons,3,99.99 Baseball,Sunglasses,6,50 72 111
ckey,Helmet,5,23 Basketball,Shoes,3,74.95 70 111
otball,Helmet,1,13.99 Soccer,Goalie Gloves,8,14.99 71 111
lf,Wedge,2,50 Baseball,Batting Helmet,5,27.99 72 111
ckey,Cup,8,20 Basketball,Sleeves,4,13 70 111
otball,Gloves,6,20.95 Soccer,Jersey,7,30.99 71 111
lf,Cart,5,66.99 Baseball,Bat,6,50.99 -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1
null null -1 -1

Answer 1

假设您的文件格式如下所示：

Name,Category,Qty,Price

我希望您使用FileReader.ReadLine()和Line.Split，如下所示：

// String csvFile = "/Users/Acer/Documents/CS1400/Assignments/InventoryApp/inventory.csv";
public static void readFromFile(String fname){
  BufferedReader fileReader = null;
  String line
  try {
     fileReader = new BufferedReader(new FileReader(csvFile));
     while ((line = fileReader .readLine()) != null) {
       String data[] = line.split(",");
       String name = data[0];
       String category = data[1];
       String quantity = data[2];
       String price = data[3];
       System.out.println(category + " " + name + " " + quantity + " " + price);                                       
     }
     fileReader.close();         
   }
   catch (IOException ioe) {
     System.out.println(ioe.getMessage());
   } 
}   

您得到“null”和“-1”的主要原因是因为最初的“for”循环没有意义：您试图读取50个项目，而不考虑实际文件中的内容。

我看不出有什么理由从“String”转换qty和price...但是如果需要，您可以轻松地使用Integer.ParseInt（String val）和BigInteger（String val）进行转换。