Java.lang.illegalstateexception: pages must fill the whole viewpager2 (use match_parent)

The exception “java.lang.IllegalStateException: pages must fill the whole ViewPager2 (use match_parent)” occurs when using a ViewPager2 widget in Android and the child pages do not fill the entire available space within the ViewPager2. This error message suggests that we should use the “match_parent” attribute for the layout parameters of the child pages to fill the entire ViewPager2.

Let’s see an example to better understand this issue. Consider a layout file that contains a ViewPager2 widget with two child fragment pages. Each child page must be configured to fill the entire available space within the ViewPager2.

  
    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
        
    ...
    
    <!-- Child page Fragment 1 -->
    <fragment
        android:name="com.example.MyFragment1"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
        
    <!-- Child page Fragment 2 -->
    <fragment
        android:name="com.example.MyFragment2"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
        
  
  

In this example, both MyFragment1 and MyFragment2 must have their layout_width and layout_height attributes set to “match_parent”. This ensures that both fragments fill the entire available space within the ViewPager2 and avoids the IllegalStateException being thrown.