無法使用BufferedWriter寫入文件

Question

我有這種方法列出目錄中的文件，我需要將它們寫入文件。顯然我的

System.out.println（）; 能夠列出文件及其大小和它們被修改的日期。但是我的bufferedWriter不會在文件中寫任何東西。這是我的方法;

public void walk(String path, int limit) throws IOException { 

      File root = new File(path); 
      File[] list = root.listFiles(); 
      File rep = new File("report.txt"); 
      SimpleDateFormat sdf = new SimpleDateFormat("MMM/dd/yyyy HH:mm:ss"); 
      if (list == null) return; 
      long size; 
      BufferedWriter bw = new BufferedWriter(new FileWriter(rep)); 
      for (File f : list) { 
      size = f.length()/1000/1000; 
       if (f.isDirectory()) { 
        walk(f.getAbsolutePath(), limit); 
       } 
       else { 
       if(size >= limit){ 
        System.out.println("File:" + f.getAbsoluteFile() + " " + size + "MB Last Modified Date: " + sdf.format(f.lastModified())); 
        bw.write("File:" + f.getAbsoluteFile() + " " + size + "MB Last Modified Date: " + sdf.format(f.lastModified()) + "\n"); 

        } 
       } 
      } 
      bw.close(); 
     } 

我失蹤了什麼？我需要編寫Out to the file report.txt文件，但文件是空的。

Answer 1

我認爲這是因爲你試圖通過遞歸調用自己時，打開多個緩衝作家到同一個文件。嘗試在此方法之外創建作者，並將其作爲參數傳遞。

---

例

public void myCallingMethod() throws IOException{ 
    File rep = new File("report.txt"); 
    BufferedWriter bw = new BufferedWriter(new FileWriter(rep)); 
    walk("my/path", 4, bw); 
    bw.close(); 
} 

Answer 2

您需要在關閉前執行

java.io.BufferedWriter#flush()

。

Answer 3

嘗試調用flush方法，你叫寫梅索德等之後：

bw.write("File:" + f.getAbsoluteFile() + " " + size + "MB Last Modified Date: " + sdf.format(f.lastModified()) + "\n"); 
bw.flush(); 

flush方法刷新您的流文件

Answer 4

下面是可能解決問題的代碼EM。 我也一樣。

public class example { 
    public static void main(String[] args) throws IOException { 

    // Directory path here 
    String path = "C:\\"; 
    SimpleDateFormat sdf = new SimpleDateFormat("MMM/dd/yyyy HH:mm:ss"); 

    File folder = new File(path); 
    File[] listOfFiles = folder.listFiles(); 
    File file = new File("report.txt"); 
    if (!file.exists()) { 
     file.createNewFile(); 
    } 
    FileWriter fw = new FileWriter(file.getAbsoluteFile()); 
    BufferedWriter bw = new BufferedWriter(fw); 
    long size; 
    int limit = 2; 
    for (File f : listOfFiles) { 
     size = f.length()/1000/1000; 

     if (size >= limit) { 
      System.out.println("File:" + f.getAbsoluteFile() + " " + size 
        + "MB Last Modified Date: " 
        + sdf.format(f.lastModified())); 
      bw.write("File:" + f.getAbsoluteFile() + " " + size 
        + "MB Last Modified Date: " 
        + sdf.format(f.lastModified())); 
     } 

    } 
    bw.close(); 
} 

}

Answer 5

定義這樣

StringBuilder fileData = new StringBuilder(); 

一個變量，並更換

bw.write("File:" + f.getAbsoluteFile() + " " + size + "MB Last Modified Date: " + sdf.format(f.lastModified()) + "\n"); 
bw.flush(); 

隨着

fileData.append("File:").append(f.getAbsoluteFile()).append(" ").append(size) 
    .append("MB Last Modified Date: ").append(sdf.format(f.lastModified())) 
    .append("\n") ; 

而且for循環寫fileData後提交

bw.write(fileData.toString()); 
bw.close();