onScrollListener for WebViewClient Android

Question

I have an Android WebView, and I want to detect scrolls in it to hide a bar I have at the bottom of the screen, but I cannot even seem to detect the scroll listener.

Firstly, this declares my webview

mWebView.setWebViewClient(new myWebViewClient());

And in my layout I have

<WebView
    android:id="@+id/activity_main_webview"
    android:layout_width="fill_parent"
    android:clickable="false"
    android:layout_height="fill_parent"
    android:layout_alignParentTop="true"
    android:layout_above="@id/buttonBar"
    android:visibility="gone">
</WebView>

And then in here, I presume I should be able to detect on scroll changes, but it doesn't recognise the Override method

public class myWebViewClient extends WebViewClient{
    @Override
    protected void onScrollChanged (int l, int t, int oldl, int oldt){
        String testString = Integer.toString(t);
        Log.d("Testing", testString);
    }
}

I think it may be to do with that I extend WebViewClient and onScrollChanged isn't valid, but then how would I change this so I am able to detect a scroll within the webview as I wish to hide the button bar at the bottom of the screen when scrolling up and reappear when scrolling down.

Thanks

EDIT

My webview now looks like this:

<test.application.ObservableWebView
    android:id="@+id/scrollableWebview"
    android:layout_width="fill_parent"
    android:clickable="false"
    android:layout_height="fill_parent"
    android:layout_alignParentTop="true"
    android:layout_above="@id/buttonBar"
    android:visibility="gone"/>

Then I declare it as so, and then in my oncreate I have the following

ObservableWebView mWebView;

mWebView = (ObservableWebView) findViewById(R.id.scrollableWebview);
            mWebView.clearCache(true);
            mWebView.setWebViewClient(new myWebViewClient());
            mWebView.getSettings().setJavaScriptEnabled(true);
            mWebView.loadUrl(currentURL);



            mWebView.setOnScrollChangedCallback(new ObservableWebView.OnScrollChangedCallback(){
                public void onScroll(int l, int t){
                    String testString = Integer.toString(t);
                    Log.d("Testing", testString);
                }
            });


    FATAL EXCEPTION: main
Process: test.application, PID: 5143
java.lang.RuntimeException: Unable to start activity ComponentInfo{test.application/test.application.MainActivity}: android.view.InflateException: Binary XML file line #72: Error inflating class test.application.ObservableWebView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2354)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1322)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5300)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
Caused by: android.view.InflateException: Binary XML file line #72: Error inflating class test.application.ObservableWebView
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:757)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2221)
at test.application.MainActivity.onCreate(MainActivity.java:62)
at android.app.Activity.performCreate(Activity.java:6088)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416) 
at android.app.ActivityThread.access$900(ActivityThread.java:154) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1322) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5300) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 
Caused by: java.lang.ClassNotFoundException: Didn't find class "test.application.ObservableWebView" on path: DexPathList[[zip file "/data/app/test.application-1/base.apk"],nativeLibraryDirectories=[/vendor/lib64, /system/lib64]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
at android.view.LayoutInflater.createView(LayoutInflater.java:571)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378) 
at android.app.Activity.setContentView(Activity.java:2221) 
at test.application.MainActivity.onCreate(MainActivity.java:62) 
at android.app.Activity.performCreate(Activity.java:6088) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2416) 
at android.app.ActivityThread.access$900(ActivityThread.java:154) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1322) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5300) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 
Suppressed: java.lang.ClassNotFoundException: Didn't find class "test.application.ObservableWebView" on path: DexPathList[[dex file "/data/data/test.application/files/instant-run/dex/slice-support-annotations-24.0.0-alpha1_970e9cd91c4c5137fd4a02c13abfe400ea2225d3-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_9-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_8-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_7-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_6-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_5-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_4-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_3-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_2-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_1-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-slice_0-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-internal_impl-24.0.0-alpha1_956ff9371be37fc55e1d852ca9d22c472953ad20-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-com.google.android.gms-play-services-measurement-8.4.0_f4c6c892c1fde4f59a633646b2a693f4e8f51799-classes.dex", dex file "/data/data/test.application/files/instant-run/dex/slice-com.google.android.gms-play-services-basement-8.4.0_38903af7dee8af1f1e19ad
05-17 19:59:34.349 5143-5143/test.application D/AppTracker: App Event: crash

[http://stackoverflow.com/a/14753235/4049612](http://stackoverflow.com/a/14753235/4049612) check this — Krishna, May 10 '16 at 19:27
@Krishna I saw that but I have no idea where ObservableWebView is coming from and cannot seem to work it out! — Navvy, May 10 '16 at 19:36
You might find the selected answer [here](http://stackoverflow.com/questions/14752523/how-to-make-a-scroll-listener-for-webview-in-android) useful — ishmaelMakitla, May 10 '16 at 19:37
@Navvy ObservableWebView is customized web view. You must add ObservableWebView in xml insted Webview — Krishna, May 10 '16 at 19:39

score 2 · Accepted Answer · edited May 23 '17 at 12:32

2

This is a potential duplicate of How to make a Scroll Listener for WebView in Android. But perhaps some guidance on how to implement the solution in your situation might be more helpful.

First off, you create class, call it ObservableWebView which extends WebView. You can look at the class definition here.

Secondly, as stated here you need to "upgrade" your Webview XML into:

 <com.YourPackageName.ObservableWebView
    android:id="@+id/activity_main_webview"
    android:layout_width="fill_parent"
    android:clickable="false"
    android:layout_height="fill_parent"
    android:layout_alignParentTop="true"
    android:layout_above="@id/buttonBar"
    android:visibility="gone" />

Finally, you implement the actual scroll listener like this:

//First, lookup the "custom" `ObservableWebView` **instead** of `WebView`
ObservableWebView yourObservableWebView  = (ObservableWebView) findViewById(R.id.activity_main_webview);
//then set the scroll callback
 yourObservableWebView.setOnScrollChangedCallback(new OnScrollChangedCallback(){
    public void onScroll(int l, int t){      
       String testString = Integer.toString(t);
       Log.d("Testing", testString);
    }
 });

I hope this helps you understand what you need to do to implement the suggested solutions.

edited May 23 '17 at 12:32

Community

1
1

answered May 10 '16 at 19:59

ishmaelMakitla

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Thank you, this is more what I needed, I think I was definitely missing chunks, although now, I also have onPageStarted/ onPageFinished which aren't working? – Navvy May 10 '16 at 20:02
My suggestion is that you test the proposed solution and indicate if it works, then you can start introducing onPageStarted/ onPageFinished. Please give it a try and let us know if this helps you. – ishmaelMakitla May 10 '16 at 20:11
Hi, is your problem of adding an onScrollListener for WebViewClient Android solved? If the suggested answer was useful, please accept the answer so that your question can be marked as answered and not appear under unanswered questions. Enjoy! – ishmaelMakitla May 11 '16 at 21:02
apologies I have been away, I've managed to get semi far with it, but now when I open my application it just crashes out - I've edited above with what I've done to see if anyone can help. – Navvy May 17 '16 at 18:49
Actually, my mistake, it works - thanks for your help makes more sense now what's going on! – Navvy May 17 '16 at 19:26

onScrollListener for WebViewClient Android

1 Answers1