如何使用此代码在webview中添加对话框

Question

我有这个webview代码工作正常但我想添加一个加载对话框。我尝试过几次，但是当我将dialog代码放入我的代码时，webview一直崩溃。请帮帮我。

import java.net.URL;

public class DisplayMessageActivity extends ActionBarActivity {
ProgressDialog mProgress;

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    // Checks the orientation of the screen
    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
        Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
    }
  }
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_message);
    if (savedInstanceState != null)
          ((WebView)findViewById(R.id.webview)).restoreState(savedInstanceState);

    // Get the message from the intent
    Intent intent = getIntent();
    String message = intent.getStringExtra(banks.EXTRA_MESSAGE);

    WebView myWebView = (WebView) findViewById(R.id.webview);
    myWebView.loadUrl(message);
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    myWebView.getSettings().setBuiltInZoomControls(true);
    myWebView.setWebViewClient(new WebViewClient());
    String url = message;

    myWebView.setDownloadListener(new DownloadListener() {
        public void onDownloadStart(String url, String userAgent,
                                    String contentDisposition, String     mimetype,
                                    long contentLength) {
            Intent i = new Intent(Intent.ACTION_VIEW);
            i.setData(Uri.parse(url));
            startActivity(i);
        }
    });


}

}