Android Webview: Execution of javascript from java method called from javascript

Question

I have the following javascript code:

    function mine()
    {
        var i = 3;
        AndroidObject.call();
    }

where AndroidObject is javascript interface to java. It has method call

    WebView myWebView;

    public void call()
    {
        runOnUiThread(new Runnable()
        {
            @Override
            public void run()
            {
                myWebView.loadUrl('javascript:alert(i);');
            }
        });
    }

The following code will produce error while execution " i is not defined " in javascript, since javascript will be executed not in the context where java code was called from.

Is it possible to execute JS from java method in the same context, i.e. to make "i" visible in the case above?

"i" is integer in this example, but it may be object of ANY type.

Thanks.

why is `i` even there then? can you post your `alert()` function? — James McCracken, Oct 10 '12 at 16:24

score 1 · Answer 1 · answered Oct 26 '12 at 10:13

Suppose i is an integer,

function mine()

 {

var i = 3;

AndroidObject.call(i);

}

and

WebView myWebView;

public void call(Integer i)
{
Integer temp = i;
    runOnUiThread(new Runnable()
    {
        @Override
        public void run()
        {
            myWebView.loadUrl('javascript:alert(' + temp + ');');
        }
    });
}

Mohsen Afshin · Answer 2 · 2012-10-11T08:58:01.237

0

I suggest you to create a function to get value of i if your i variable is global, like this:

var i = 20;

function getValueOfI() {
     return i;
}

and in your java code use something like this:

 myWebView.loadUrl('javascript:alert(getValueOfI());');

Updated If you want to achieve the same with local variables:

 function mine()
    {
        var i = 3;
        AndroidObject.call(i);
    }

where AndroidObject is javascript interface to java. It has method call

WebView myWebView;

public void call(final Integer i)
{
    runOnUiThread(new Runnable()
    {
        @Override
        public void run()
        {
            myWebView.loadUrl("javascript:alert(" + i + ");");
        }
    });
}

public void call(final String i)
{
    runOnUiThread(new Runnable()
    {
        @Override
        public void run()
        {
            myWebView.loadUrl("javascript:alert(" + i + ");");
        }
    });
}

public void call(final Boolean i)
{
    runOnUiThread(new Runnable()
    {
        @Override
        public void run()
        {
            myWebView.loadUrl("javascript:alert(" + i + ");");
        }
    });
}

edited Oct 11 '12 at 08:58

answered Oct 10 '12 at 16:39

Mohsen Afshin

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Of cource it will work with global variables :) , but the question was mostly how to do it without globals. – Alexander Ponomarev Oct 11 '12 at 06:08
Sorry, I forgot to say that "i" can be of any type, not only integer. I edited the question. – Alexander Ponomarev Oct 11 '12 at 07:26
If we was in C#, we could use dynamic keyword to detect the type of 'i' dynamically. But here we can use Object, can't we? – Mohsen Afshin Oct 11 '12 at 07:44
Overloaded methods work definitely. Define as much as types as your object may be. – Mohsen Afshin Oct 11 '12 at 08:59
What should I do if this is Javascript object, like function? :) I mean any javascript object. – Alexander Ponomarev Oct 11 '12 at 09:56
Then I guess If you use an overloaded method with an Object argument, then you will be able to access it. – Mohsen Afshin Oct 11 '12 at 10:19
Unfortunately object being passed to java is not javascript object that I can return back to JS. – Alexander Ponomarev Oct 11 '12 at 12:19

Android Webview: Execution of javascript from java method called from javascript

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