Question

我有这个方法列出目录中的文件，我需要将其写入文件。显然是我的

的System.out.println（）; 能够列出文件及其大小和修改日期。但我的bufferedWriter不会在文件中写任何东西。这是我的方法;

 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();
        }

我想念的是什么？我需要将Out写入文件report.txt，但该文件为空。

Answer 1

我认为这是因为当你通过递归调用自己时，你试图将多个缓冲的编写器打开到同一个文件中。尝试在此方法之外创建编写器并将其作为参数传递。

示例

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

尝试在调用write方法之后调用flush方法，如：

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

flush方法将您的流刷新到文件

Answer 3

以下是可能解决您问题的代码。我试过了同样的事。

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 4

定义一个像这样的变量

StringBuilder fileData = new StringBuilder();

并替换

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

使用

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

在for循环后将fileData写入文件

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

Answer 5

在结束前你需要做一个

java.io.BufferedWriter#flush()

。

无法使用BufferedWriter写入文件

5 个答案: