java - 简单的文件写入，但不起作用

Question

我浏览了一些如何用 Java 写入文件的示例，我认为我做得对......显然不是。这里出了什么问题，它甚至没有创建要写入的文件。没有错误，只是没有写入文件。

File inputFile = new File("pa2Data.txt");
File outputFile = new File("pa2output.txt");
Scanner fileIn = new Scanner(inputFile);
BufferedWriter fout = new BufferedWriter(new FileWriter(outputFile));

while(fileIn.hasNext()){
    String theLine = readFile(fileIn);
    fout.write("Infix expression: " + theLine + '\n');
    postfixExpression = infixToPostFix(theLine);
    String op = postfixExpression.toString();
    fout.write("Postfix Expression: " + op + '\n');

    theLine = readFile(fileIn);
    StringTokenizer st = new StringTokenizer(theLine);
    for(int i = 0; i < theValues.length; i++)
        theValues[i]  = Integer.parseInt(st.nextToken());
        int answer = postfixEval(postfixExpression, theValues);
        fout.write("Answer: " + answer + '\n' + '\n'); 
    }
    fileIn.close();
    fout.close();

}//end main

Answer 1

我将您的代码简化为一个工作示例，您可以从中继续...

public class Test{
  public static void main(String[] args){
    try {
      File inputFile = new File("pa2Data.txt");
      File outputFile = new File("pa2output.txt");
      Scanner fileIn = new Scanner(inputFile);
      BufferedWriter fout = new BufferedWriter(new FileWriter(outputFile));

      while(fileIn.hasNext()){
        String theLine = fileIn.next();
        fout.write("Infix expression: " + theLine + '\n');
      }
      fileIn.close();
      fout.close();
   } catch(Exception e){
      e.printStackTrace();
   }
 }

}

请注意，我已经更改了 readFile(fileIn); fileIn.next();从扫描仪读取。这样做是因为您在 while 循环的条件中使用了hasNext()`。