Trying to parse JSON of a web page before it's loaded in a WebView

Question

I need to parse JSON content out of every page in my WebView, before it is shown to the user.

In order to do so, I need to parse the JSON element and only then I’m able to use the shouldOverrideUrlLoading method. I can’t use it before I’ve parsed the JSON object because I rely on that element as part of my implementation of that method.

I have created a variable called jsonParsed to indicate whether I have all needed information out of the JSON object. At first, it is initialized to be false.
When I get a response from the server I know the object was parsed so I change the variable to be true in the onLoaded method, and then the code is ready to get the information and check it.

This is the wanted process:

Opening new page by the user
Entering automatically to shouldOverrideUrlLoading and then to the if statement(JSON wasn't parsed yet)
Getting the JSON response in OnResponse
Going back to shouldOverrideUrlLoading and entering the else statement (JSON is parsed)

As you can see, each process should go through both if and else statements, the if before the JSON was parsed, and the else after it was parsed.

The problem:

shouldOverrideUrlLoading is reached every step 1, but each time it goes into a different statement. The first time goes into the if (steps 2+3), and the next one goes into the else (step 4) and this process repeats itself...

I think the this line webView.loadUrl(loadingURL); doesn't call shouldOverrideUrlLoading for some reason.

Here is my code snippet:

    @Override
    public void onPageStarted(WebView view, String url, Bitmap favicon)
    {
     super.onPageStarted(view, url, favicon);
     mProgressDialog.show();                        
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView wView, String url){
                                    loadingURL=url;
            if (!jsonParsed){
            /** JSON object is not parsed
            * Some code for adding request 
to requestQueue and than loading new url in onResponse method... */                          
            }

            else {                         
        /** JSON object is parsed, starting checking process
        * I need to check this URL and decide whether or not to override it*/                               
          jsonParsed=false;
          Root root = new Gson().fromJson(jsonResponse, Root.class);
          for (Page page : root.query.pages.values()) {
          firstParagraph=page.extract; //Parsing process, works fine
                                        }
          if (firstParagraph!=null) {
         //If the webView isn't Wikipedia's article, it will be null
         if (firstParagraph.contains(allowedContent)) {
        //Passing URL to view
         return true;
         }
    }
     return false; //The URL leads to unallowed content  
                                    }
                                }

    @Override
    public void onPageFinished(WebView view, String url) {
     CloseBlocksAndDisableEdit(view);
      mProgressDialog.dismiss();
                         }

    private final Response.Listener<String> onLoaded = new Response.Listener<String>() {
    @Override
        public void onResponse(String response) {
         jsonResponse=response; //Getting response
         jsonParsed=true; //Object was examined
         webView.loadUrl(loadingURL);
       }
    };

What can be the cause of this problem?
If it's not possible in this way, I'd like to know which way is better...

What ever statement you use inside webview client is got looped...meaning you have to use catch mechanism to get what you want and end the loop. — EngineSense, May 14 '17 at 12:55
I didn't really understand what has got looped here. I have edited my question, trying to find more specific problem... — Tal Barda, May 19 '17 at 13:46

score 1 · Accepted Answer · edited May 23 '17 at 12:18

I have found this answer: https://stackoverflow.com/a/6739042/7483311

It is written in this answer:

After some research I conclude that despite what most of the tutorials out there say, shouldOverrideUrlLoading() does not get called when:

You load a URL like: loadUrl("http://www.google.com");

The browser redirects the user automatically via an HTTP Redirect.

This probably makes my code impposible. In this line: webView.loadUrl(loadingURL);, I'm making an https request that was not made by the user in the WebView, and that's why it doesn't call shouldoverrideurlloading.

Trying to parse JSON of a web page before it's loaded in a WebView

1 Answers1