How to call native function from cordova 3.x

How can I call a native function from cordova/phonegap webview for example for showing an ad.

EDIT: OK I FUNALLY GOT IT and I'm gonna write some steps for all of you who don't know how to do that (just to spare 2 days of your lifetime :D)

A) if you have just cordova/phonegap and and wish to call from js do this:

1) Replace the following code with your existing DroidGap Activity.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    super.init(); // Calling this is necessary to make this work
    appView.addJavascriptInterface(this, "MainActivity");

    /* "this" points the to the object of the current activity. "MainActivity" is used to refer "this" object in JavaScript as in Step 3. */

    super.loadUrl("file:///android_asset/www/index.html");
}

2) Add the custom function in current (this) activity as following.

@JavascriptInterface
public void customFunctionCalled() {
    Log.e("Custom Function Called", "Custom Function Called");
}

3) Now call this function from your HTML/JavaScript code as following.

 window.MainActivity.customFunctionCalled();

B.1) if you have cordova/phonegap implemented in a webview and wish to call from js do this: (and want to call normal function)

1) Add this to the main java file:

JavaScriptInterface jsInterface = new JavaScriptInterface(this);
webView.getSettings().setJavaScriptEnabled(true);
webView.addJavascriptInterface(jsInterface, "JSInterface");

2) Declare the class JavaScriptInterface:

public class JavaScriptInterface {
    private Activity activity;

    public JavaScriptInterface(Activity activiy) {
        this.activity = activiy;
    }

    @JavascriptInterface
    public void showLog(){
        Log.v("blah", "blah blah");
    }

}

3) Call it from js with `window.JSInterface.showLog();

B.2) if you have cordova/phonegap implemented in a webview and wish to call from js (and want to call UI function, like a toast) do this:

1) Add this to the main java file:

JavaScriptInterface jsInterface = new JavaScriptInterface(this);
webView.getSettings().setJavaScriptEnabled(true);
webView.addJavascriptInterface(jsInterface, "JSInterface");

2) Declare the class JavaScriptInterface:

public class JavaScriptInterface {
    private Activity activity;

    public JavaScriptInterface(Activity activiy) {
        this.activity = activiy;
    }

    @JavascriptInterface
    public void myFunction()
    {
        activity.runOnUiThread(new Runnable() {
            public void run() {
                //Code that interact with UI
                showToast();
            }
        });

    }

}

3) Add the toast function underneath:

public void showToast(){
    Toast.makeText(getApplicationContext(), "this is my Toast message!!! =)",
               Toast.LENGTH_LONG).show();
}

4) Call it with `window.JSInterface.myFunction();

As you see if you need a function that uses the UI you need to wrap your function into activity.runOnUiThread so that it can get called from js.

*If you want to call from java a jquery method do this:

Java:

cordova_webview.loadUrl("javascript:window.functionn()");

Javascript:

window.function = punish;

Have a nice day!

In the .java file

public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    super.init(); // Calling this is necessary to make this work

    appView.addJavascriptInterface(this, "MainActivity");

    super.loadUrl(Config.getStartUrl());

}

In the javascript

window.MainActivity.customFunctionCalled();

This will only work on TargetSDK<17 . An androidManifest.xml targetSDK need to be set < 17. And for TargetSDK >=17 , I guess you'll need to create some custom plugin. I use this process lowering my target SDK for now.