Native methods can be called from a Webview using JavaScript. To add a interface to webview, the method addJavascriptInterface can be used. Here is an example.

First, create a class with public methods with @JavascriptInterface annotations (Not @JavaScriptInterface).

public class JSInterface {
...
@JavascriptInterface
public void toastMe(String text) {
    Toast.makeText(mContext, text, Toast.LENGTH_SHORT).show();
}

Then attach the class name as the Webview's JavascriptInterface.

webview.addJavascriptInterface(new JSInterface(this), "JSInterface");

Call JSInterface.toastMe(text) from Webview's Javascript instance.

var text = "I want to be toasted";
JSInterface.toastMe(text);

Here is a screenshot of the whole thing.

I used the text from webview to show as Toast using native Java.

Get the complete project source from my Github repository Android-JavascriptInterface-Sample.