webView.canGoBack() not working when using loadDataWithBaseURL()

Question

I have a WebView in my application that displays HTML data downloaded from a webpage. Why do I load the HTML rather than the URL alone? Well, in order for me to allow offline search, I download the HTML data and store it on an SQL database.

Everything works well, and subsequent calls to loadDataWithBaseUrl() work well, and keep on loading correctly on my WebView, but whenever the user presses the back key, the user is just taken back to the last activity on the stack, rather than going back.

I tried using the following code:

// Check if the key event was the Back button and if there's history
if ((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack()) {
    myWebView.goBack();
    return true;
}

But then I tried forcing the WebView to go back, without checking if it could or not, via:

// Check if the key event was the Back button and if there's history
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
    myWebView.goBack();
    return true;
}

but nothing happens, it just stays on the same place.

As an FYI, I've tried passing null and an actual URL when calling loadData(), here's how I have it set right now:

view.loadDataWithBaseURL(mUrl, mHtmlData, SearchUtils.MIME_TYPE, SearchUtils.CHARSET, "");

I read this answer but I am hoping for better luck.

Solution 1

So I actually decided to implement my own "back" functionality, not sure if this will work for everybody´s intentions, but it worked for me.

First,

Create an ArrayList that will store the urls you visit in chronological order.

private ArrayList<String> searchHistory;

from onCreate() initialize it:

searchHistory = new ArrayList<String>();

Now, each time you load a url, simply add the url string to the history:

String mUrl = "www.example.com";
searchHistory.add(mUrl);
mWebView.loadDataWithBaseURL(mUrl,...);

And, when user presses back, handle that by removing the eldest entry of the array, and then loading the last one remaining after deletion:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {     
    if ((keyCode == KeyEvent.KEYCODE_BACK) && searchHistoryPos > 0) {
        Constants.LogMessage("Handling back keyevent");
        //remove eldest entry
        searchHistory.remove(mUrl);
        //make the url-to-load be the latest entry after deletion
        mUrl = searchHistory.get(searchHistory.size);
        //load the new url
        mWebView.loadDataWithBaseURL(mUrl...);
        }
    }

Of course, when calling loadDataWithBaseUrl, I am also passing the pre-loaded HTML data.

Hope that helps!

Solution 2

another simple solution is to save the first url and than check if is equal to the current url

field :

String mFirstUrlLoaded = "";

than :

mFirstUrlLoaded = "your first url.....";

than :

@Override
public void onBackPressed() {
        if (!mFirstUrlLoaded.equals(mWebView.getUrl())) { 
        mWebView.goBack();
}

Solution 3

put first link on history field

view.loadDataWithBaseURL(mUrl, mHtmlData, SearchUtils.MIME_TYPE, SearchUtils.CHARSET, mUrl);

Comments

[Giru Bhai]

did you also save html data with urls?