import java.util.*;
public class MyClass {
public static void main(String args[]) {
ArrayList<String> al1 = new ArrayList<String>();
al1.add("java");
al1.add("c++");
al1.add("c#");
al1.add("python");
al1.add("javascript");
al1.add("c");
System.out.println(al1);
List<String> unmodifiableList= Collections.unmodifiableList(al1);
unmodifiableList.add("php"); // Error
}
}
/*
run:
[java, c++, c#, python, javascript, c]
Exception in thread "main" java.lang.UnsupportedOperationException
at java.base/java.util.Collections$UnmodifiableCollection.add(Collections.java:1060)
at MyClass.main(MyClass.java:17)
*/