“旋转轮”从 SD 卡删除文件夹时的进度对话框

Question

我想在从 SD 卡删除文件夹时用旋转轮显示简单的进度对话框。我有以下一段代码：

  ProgressDialog dialog = ProgressDialog.show(this, "",
            "Please wait for few seconds...", true);

private void deleteCache() {

    File f = new File(Environment.getExternalStorageDirectory()
            .getAbsoluteFile() + Constants.DATA_DIR);
    deleteDirectory(f);
    dialog.dismiss();
}

 private void deleteDirectory(File path) {
        if (path.exists()) {
            File[] files = path.listFiles();
            for (int i = 0; i < files.length; i++) {
                if (files[i].isDirectory()) {
                    deleteDirectory(files[i]);
                } else {
                    files[i].delete();
                }
            }
        }
        return (path.delete());
    }

应该在 deleteDirectory(f); 之前显示对话框，并在结束后将其关闭。但我从未看到任何对话框，尽管该文件夹已被删除。

Answer 1

这个答案也遍布 StakcOverflow。使用 AsyncTask 它将在不同的线程上运行并具有三个阶段。一个是您将加载轮子的前一个，一个是完成后您将关闭它的后一个……然后是实际工作的背景。

Answer 2

private void deleteCache() {
  ProgressDialog dialog = ProgressDialog.show(this, "",
    "Please wait for few seconds...", true);

  Runnable myRun = new Runnable() {
    public void run() {
      File f = new File(Environment.getExternalStorageDirectory()
        .getAbsoluteFile() + Constants.DATA_DIR);
      deleteDirectory(f);

      runOnUiThread(new Runnable() {
        @Override
        public void run() {
          dialog.dismiss();
        }
      });
    }
  }
}

private void deleteDirectory(File path) {
  if (path.exists()) {
    File[] files = path.listFiles();
    for (int i = 0; i < files.length; i++) {
      if (files[i].isDirectory()) {
        deleteDirectory(files[i]);
      } else {
        files[i].delete();
      }
    }
  }

  return (path.delete());
}

Answer 3

像这样修改你的代码，

 ProgressDialog dialog = ProgressDialog.show(this, "",
        "Please wait for few seconds...", true);
        new Thread(new Runnable() {
        public void run() {
              File f = new File(Environment.getExternalStorageDirectory()
        .getAbsoluteFile() + Constants.DATA_DIR);
deleteDirectory(f);
   private void deleteDirectory(File path) {
    if (path.exists()) {
        File[] files = path.listFiles();
        for (int i = 0; i < files.length; i++) {
            if (files[i].isDirectory()) {
                deleteDirectory(files[i]);
            } else {
                files[i].delete();
            }
        }
    }
    return (path.delete());
}


            handler.sendEmptyMessage(0);

        }
    }).start();

    handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {

            try {



                progressDialog.dismiss();
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            }
        }
    };

我不确定为什么会发生这种情况。由于您的代码在单个线程中完成所有操作，因此进度对话框不会很快显示。因此，尝试在单独的线程中处理其他事情可以解决这个问题。