I am preparing for an OCPJP 8 exam for the next 2 months and currently I this one got my attention as I dont understand why

public class BiPredicateTest {
    public static void main(String[] args) {
        BiPredicate<List<Integer>, Integer> containsInt = List::contains;
        List<Integer> ints = java.util.Arrays.asList(1,20,20);
        ints.add(1);
        ints.add(20);
        ints.add(20);
        System.out.println(containsInt.test(ints, 20));
        
        BiConsumer<List<Integer>, Integer> listInt = BiPredicateTest::consumeMe;
        listInt.accept(ints, 15);
        
    }
    
    public static void consumeMe(List<Integer> ints, int num) {
        ints.removeIf(i -> i>num);
        ints.forEach(System.out::println);
    }
}

this clearly is going to compile OK! but when you run it you will see the exception like this

C:\Users\user\Documents>javac BiPredicateTest.java

C:\Users\user\Documents>java BiPredicateTest
true
Exception in thread "main" java.lang.UnsupportedOperationException
        at java.util.AbstractList.remove(AbstractList.java:161)
        at java.util.AbstractList$Itr.remove(AbstractList.java:374)
        at java.util.Collection.removeIf(Collection.java:415)
        at BiPredicateTest.consumeMe(BiPredicateTest.java:22)
        at BiPredicateTest.main(BiPredicateTest.java:17)

I need some help here to understand why the asList method is not working with removeIf? i assume it will return an instance of ArrayList which implements removeIf method!.

Any answer will be appreciated.

cheers!

UPDATE: April 16,2022 The error is not happening anymore even you use the java.util.Arrays.asList, what I notice is that

• the latest java 1.8* implementation is not using internal ArrayList class anymore but the class under java.util package.
• the List interface also has default implementation now.