android.view.ViewGroup.getViewTreeObserver()' on a null object reference

[karim-eg]

Hello, i am trying to display blur at recyclerview customview but it show me this Error:

Attempt to invoke virtual method 'android.view.ViewTreeObserver android.view.ViewGroup.getViewTreeObserver()' on a null object reference

here the code that i used:

float flt = 12f;
View decorView = getWindow().getDecorView();

ViewGroup rootView = (ViewGroup) decorView.findViewById(R.id.content);

Drawable windowBackground = decorView.getBackground();

blurView.setupWith(rootView, new RenderScriptBlur(MainActivity.this))
.setFrameClearDrawable(windowBackground)
.setBlurRadius(flt)
.setBlurAutoUpdate(true);

The XML Code:

<LinearLayout 
  android:id="@+id/content" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:layout_marginLeft="4dp" 
  android:layout_marginTop="2dp" 
  android:layout_marginRight="4dp" 
  android:layout_marginBottom="10dp" 
  android:orientation="vertical"> 
          <eightbitlab.com.blurview.BlurView 
           android:id="@+id/blurView" 
           android:layout_width="match_parent" 
           android:layout_height="match_parent" 
           android:orientation="vertical"> 
                     <TextView 
                      android:id="@+id/text1" 
                      android:focusable="false" 
                      android:layout_width="wrap_content" 
                      android:layout_height="wrap_content" 
                      android:padding="8dp" 
                      android:text="TextView" 
                      android:textSize="12sp" 
                      android:textColor="#000000" /> 
          </eightbitlab.com.blurview.BlurView> 
 </LinearLayout>

• Library Version: 2.0.3
• Android Version: 12

[Dimezis]

Your decorView.findViewById(R.id.content) is null most likely

[karim-eg]

Your decorView.findViewById(R.id.content) is null most likely

But i've added the linear as you see in code findViewById(R.id.content)

i've tried the same source on another new app and it worked, i don't know why it doesn't work here

[Dimezis]

I don't see the full code, so I can't tell you why. But if it's null, it's not a library bug

[karim-eg]

I don't see the full code, so I can't tell you why. But if it's null, it's not a library bug

the code below is inside recyclerView Adapter:

float flt = 12f;
View decorView = getWindow().getDecorView();

ViewGroup rootView = (ViewGroup) decorView.findViewById(R.id.content);

Drawable windowBackground = decorView.getBackground();

blurView.setupWith(rootView, new RenderScriptBlur(MainActivity.this))
.setFrameClearDrawable(windowBackground)
.setBlurRadius(flt)
.setBlurAutoUpdate(true);

[Dimezis]

So is it null?

[karim-eg]

Attempt to invoke virtual method 'android.view.ViewTreeObserver android.view.ViewGroup.getViewTreeObserver()' on a null object reference

Yes, But Finally i've solved it after i used this condition:

if (rootView != null) {
rootView.getViewTreeObserver();
}

[Dimezis]

If that solves your issue, there's just something wrong with your setup. Why are you setting the direct parent of the BlurView as the root view? Why are you looking it up in the decorView?

[karim-eg]

If that solves your issue, there's just something wrong with your setup. Why are you setting the direct parent of the BpurView as the root view? Why are you looking it up in the decorView?

Yes, as I mentioned this code is inside Recycler View Adapter linked with custom view

This is same like Facebook posts but the post background is blurred instead of white color, this is the nearest example.