How to create Immutable List in java?

Question

I need to convert mutable list object to immutable list. What is the possible way in java?

public void action() {
    List mutableList =          


        

Answer 1

Use Collections.unmodifiableList(). You pass in your original ArrayList and it returns a list that throws an exception if you try to add, remove or shift elements. For example, use return Collections.unmodifiableList(beanList); instead of return beanList; at the end of getImmutableList(). main() will throw an exception. The Collections class has methods for all of the other common collection types besides List as well.