java - 为什么我的方法只读取一行文本？

Question

我有一个方法可以读取包含 4 个部分的文本文件的各个部分:日期、名称、描述和金额，例如

4/5/2018, gel, hair product, 20.00
4/4/2018, wax, hair product, 20.00

等等...

我的问题是我的方法只会读取第一行，然后输出我的 catch 方法，说找不到该文件。

public static void showRecordedExpense(String filename)throws IOException {
    String date = "";
    String name = "";
    String description = "";
    double amount = 0.00;
     try{
         Scanner read = new Scanner(new File(filename));
         while (read.hasNextLine()){
             String oneLine = read.nextLine();
             String[] parts = oneLine.split(",");
             try {
                 date = parts[0];
                 name = parts[1];
                 description = parts[2];
                 amount = Double.parseDouble(parts[3]);
                 System.out.printf("%15s%15s%15s%20s%n", "---------------", "---------------",
                         "---------------", "---------------------");
                 System.out.printf("%15s%15s%15s%31s%n","Date", "Name", "Description","Amount");
                 System.out.printf("%15s%14s%33s%15s%n",date,name,description,amount);
                 System.out.printf("%15s%15s%15s%20s%n", "---------------", "---------------",
                         "---------------", "---------------------");
             }catch (Exception e){
                 System.out.println("no");
             } finally {
                 read.close();
             }
         }
     }catch (Exception e){
         System.out.println("The file could not be found");
     }

}

编辑:拿出终于成功的。

Answer 1

阅读here有关 finally 工作原理的详细信息。由于您与 try/catch 配对的 finally，您当前正在 while 循环的第一次迭代结束时关闭扫描程序。自您关闭文件以来， while 的下一次迭代无法再从文件中读取文件，这就是它只读取第一行的原因。考虑在 while 循环完成后取出finally并关闭扫描器。

     try{
         Scanner read = new Scanner(new File(filename));
         while (read.hasNextLine()){
             String oneLine = read.nextLine();
             String[] parts = oneLine.split(",");
             try {
                 date = parts[0];
                 name = parts[1];
                 description = parts[2];
                 amount = Double.parseDouble(parts[3]);
                 System.out.printf("%15s%15s%15s%20s%n", "---------------", "---------------",
                         "---------------", "---------------------");
                 System.out.printf("%15s%15s%15s%31s%n","Date", "Name", "Description","Amount");
                 System.out.printf("%15s%14s%33s%15s%n",date,name,description,amount);
                 System.out.printf("%15s%15s%15s%20s%n", "---------------", "---------------",
                         "---------------", "---------------------");
             }catch (Exception e){
                 System.out.println("no");
             }
         }

         read.close();
     }catch (Exception e){
         System.out.println("The file could not be found");
     }