ClassCastException ViewGroup$LayoutParams cannot be cast to ViewPager$LayoutParams

Question

My initial code line is inside the overridden method onGlobalLayout():

img.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, 100));

ClassCastException occuring in the overridden method onGlobalLayout()-

Error Log:

09-02 14:25:35.326: E/AndroidRuntime(5187): java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.support.v4.view.ViewPager$LayoutParams
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1319)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.view.View.measure(View.java:15181)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.view.View.measure(View.java:15181)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
09-02 14:25:35.326: E/AndroidRuntime(5187):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)

And when I do the following in order to resolve the above error as indicated in other SO posts:

img.setLayoutParams(new ViewPager.LayoutParams(ViewPager.LayoutParams.MATCH_PARENT, 100));

Then, I get the compile time error:

The constructor ViewPager.LayoutParams(int, int) is undefined

ViewPager in xml is defined like:

<android.support.v4.view.ViewPager
 android:id="@+id/HView"
 android:layout_width="560dp"
 android:layout_height="255dp"
 android:layout_centerHorizontal="true"
 android:layout_marginLeft="160sp"
 android:layout_marginTop="110sp"
 android:layout_marginBottom="80sp">
 </android.support.v4.view.ViewPager>

Apostles

developer.android.com/reference/android/support/v4/view/…. check the constructors. public ViewPager.LayoutParams (Context context, AttributeSet attrs) your params are wrong no constructor that takes int int as param – Geaghan

check your imports please – Expeditious

Ok I did checked that but then How to resolve it. – Apostles

@LiaPronina - android.support.v4.view.ViewPager – Apostles

what is this img? where is this in XML, whats the parent of this img – Countertype

try to use ViewGroup instead ViewPager in using LayoutParams – Expeditious

img - final ImageView img = new ImageView(getActivity()); Its parent is also dynamically created as: linearlayout = new LinearLayout(getActivity()); linearlayout.addView(img);. This is all inside android.support.v4.view.ViewPager in the xml. – Apostles

Ok try img.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 100)); – Countertype

I tried all those combinations same error. – Apostles

Answer 1

Your image already has layout params. Instead of replacing them with a new object (which is of wrong type in this case, ViewPager expects them to be ViewPager.LayoutParams), you can modify existing layout params like this:

ViewGroup.LayoutParams params = img.getLayoutParams();
params.width = ViewGroup.LayoutParams.MATCH_PARENT;
params.height = 100;
img.requestLayout();

Note that unconditionally requesting re-layout in onGlobalLayout() can be a bad idea, leading to infinite layout passes. I haven't verified it myself whether this is the case.

Dumuzi

This is causing a loop. I tried to put my code in question just after onGlobalLayout() and its working fine but I noticed that my code is getting called before onGlobalLayout(). This appears strange just like threads do. So I am bound to put it inside onGlobalLayout(). – Apostles

Yes - could you clarify why you need to modify the layout in a global layout listener? There's probably a better way. (This answer addresses the class cast exception issue.) – Dumuzi

Because I am trying to get the end position of text view and image view. See my this SO post and my own accepted answer there- http://stackoverflow.com/questions/18533224/getting-end-position-of-the-textview-and-imageview-with-respect-to-top-of-the-sc – Apostles

See I modified my own answer just now to include the img code there. – Apostles

Thanks, I am able to stop the looping by, view.getViewTreeObserver().removeOnGlobalLayoutListener(this);. – Apostles

Worked perfectly for me! – Voracity

the reason why I am trying to create a new object is because .getLayoutParams() is returning null, so what do I do in that case? – Meditate

Answer 2

Do this way

img.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 100));

UPDATE

 LayoutParams params = img.getLayoutParams();
         params.width = LayoutParams.MATCH_PARENT;
         params.height = 100;
         img.setLayoutParams(params);

Tittup

I already checked that too. Its giving the same exception but this time with the following log: 09-02 14:37:23.953: E/AndroidRuntime(5822): java.lang.ClassCastException: android.view.ViewGroup$LayoutParams cannot be cast to android.support.v4.view.ViewPager$LayoutParams – Apostles

This is working fine but causing a loop. I tried to put my code in question just after onGlobalLayout() and its working fine but I noticed that my code is getting called before onGlobalLayout(). This appears strange just like threads do. So I am bound to put it inside onGlobalLayout(). – Apostles

Answer 3

You should make sure the LayoutParam class you are using is from the correct parent Layout class. And you need to set the LayoutParams of the ViewGroup the ViewPager is sitting in, as the parent of the View that needs to know what size to allocate to the child View. For example, in your case the ViewGroup is a RelativeLayout, you need to use the RelativeLayout.LayoutParams class.

You can try following:

img.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, 100));

Fruitless