进度对话框在 android studio 中不起作用

Question

我想在我的应用程序中显示进度对话框，直到它加载 URL 并显示它。但它没有显示进度对话框。请帮我。

  setContentView(R.layout.activity_main);

    mywb = (WebView) findViewById(R.id.webView);

    ProgressDialog progressDialog = new ProgressDialog(this);

    progressDialog.setTitle("The Book Street");

    progressDialog.setMessage("Loading");

    progressDialog.setProgressStyle(progressDialog.STYLE_SPINNER);

    progressDialog.show();

    progressDialog.setCancelable(false);

    WebSettings webSettings = mywb.getSettings();

    webSettings.setJavaScriptEnabled(true);

    mywb.loadUrl("http://www.thebookstreet.com");

    progressDialog.dismiss();

    mywb.setWebViewClient(new WebViewClient());