Passing variables by @JavascriptInterface in Android

Question

As you probably know from the title I work with Android WebView . Though, I've got a specific question about @JavascriptInterface . I'm really curious if I can make the exact method which will be working on Javascript variables but will be called from Android . Let's say I have an object in Javascript which got a variable named name , then if I want to change this variable somehow I will use some kind of this function:

function () { 
    return this.name + ' my addition';
}

I would assign this function to another variable which will be used somewhere else. Now, I would like to do the same but in Android. Let's say I've got an object Object obj then this object has got it's name . My function made in @JavascriptInterface would be like this:

@JavascriptInterface
public void changeName(Object obj){
    return obj.name + " my addition";
}

If I add the JavascriptInterface to my WebView named "jsinterface" I would do this like this in Javascript :

function() { 
    jsinterface.changeName(this.name); 
}

But to be honest it doesn't work because obj.name is null then. I know that's because I do not pass the Object . Is there any trick to make this what I want or I really need to use webView.loadUlr("javascript: function() { ... }"}; ? I would like to avoid using webView here, that's why I ask this question.

Thanks for your time! :)

Answer 1

The JavaScriptInterface can only return or pass Primitive Data Types.

So it should be like this...

@JavascriptInterface
public void changeName(String obj){
   ........
}

Then, you need to turn a JavaScript Object to JSONObject. And turn the JSONObject to String. Then you can pass it to "changeName."

And turn the String to JSONObject in Java code.

@JavascriptInterface
public void changeName(String obj){
   JSONObject js = new JSONObject(obj);
   ....
}