Last post I wrote about Interfacing Javascript from Webview to native Android was about one way communication from Javascript to Android activity.

Later I tried a duplex communication between Activity and Javascript. That means -

• Call Javascript methods from Android activity
• Call Android activity methods from Javascript

are possible.

Android to Javascript

In MainActivity.java

String data = "Hello!";
webview.loadUrl("javascript:setData(\"" + data + "\");");

In index.html

function setData(data) {
    alert(data);
    }

Javascript to Android

In MainActivity.java

public class JSInterface {
    JSInterface() {}
    @JavascriptInterface
    public String getData() {
        return "Hello";
    }
}

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

In index.html

var data = JSInterface.getData();
alert(data);

Here is a preview of my setup where a javacript function is called when a button is clicked, and the javascrip call activity's function for current date string.

Check my repository Android-Javascript-Bridge for full project source.