zoom controller not working in webview in android

I am suffering from a strange problem in order to implement WebView in android. I am trying to load html5 supported web page in my WebView, but the pro开发者_StackOverflow社区blem is default zoom controller is not working in WebView. i tried with the following code.

webview.getSettings().setBuiltInZoomControls(true);
webview.invokeZoomPicker();

Can any body help regarding this.

Add this line also

WebSettings setting = wView.getSettings();
        setting.setBuiltInZoomControls(true);
        setting.setSupportZoom(true);

if work or not please reply