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Reputation: 33

Is there a way to extract objects (class instances) in JavaScript to Android using WebView?

I am trying to extract objects and lists created in JavaScript to use them inside Android application. (I have succeeded in extracting single values.) I am using addJavaScriptInterface method to implement this.

Inside test.html, I have the following script code: (I've tried without ".slice()" but did not work either)

function getList(){
var categoryTotals = {};
categoryTotals[0] = 1;
categoryTotals[1] = 2;
categoryTotals[2] = 3;
return categoryTotals.slice();
}

And the WebViewClient's onPageFinished method contains the following code:

mWebView.loadUrl("javascript:window.HTMLOUT.callAndroidList(getList());");

My JavaScriptInterface has the following function:

public void callAndroidList(final List list){
        myList = list;
        Log.d("ListTest" , "LIST 1 >>>>>>>>>>>>> " + ListTest.myList.get(0));
        Log.d("ListTest" , "LIST 2 >>>>>>>>>>>>> " + ListTest.myList.get(1));
        Log.d("ListTest" , "LIST 3 >>>>>>>>>>>>> " + ListTest.myList.get(2));
    }

When I run this code, I get NullPointerException saying that callAndroidList's parameter, list, is null. I haven't dealt much with JavaScript so I think it is possible that this is related to creation and removal of JavaScript object instances.

Could you help me out? Thanks in advance.

Upvotes: 2

Views: 304

Answers (1)

RobG
RobG

Reputation: 147473

> function getList(){ 
>     var categoryTotals = {};

That will create an object, I think you mean to create an array, so perhaps it should be:

      var categoryTotals = [];

.

>     categoryTotals[0] = 1;
>     categoryTotals[1] = 2;
>     categoryTotals[2] = 3;
>     return categoryTotals.slice();

Since you are creating an object with numeric properties, not an array, it does not have a slice method. Initializing categoryTotals as an array should fix that.

Incidentally, there does not seem to be any point in using slice to return a copy of the array. Since categoryTotals is not used for anything else, why not just return it?

Upvotes: 1

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