我想用旋转轮显示简单的进度对话框,同时从SD卡中删除文件夹.我有一段代码：

  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;结束后将其解散.但是我没有看到任何对话框,但是文件夹被删除了.

解决方法:

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();
            }
        }
    };

我不确定为什么会这样.由于您的代码在单个线程中执行所有操作,因此progressdialog不会快速显示.因此,尝试在单独的线程中处理其他事情来处理此问题.