Search⌘ K
AI Features
Home
Courses
The Java Interview Handbook: 300+ Interview Questions

Collection Types and Iteration

Explore the core Java collections types and understand thread safety mechanisms like CopyOnWriteArrayList and ConcurrentHashMap. Learn how to safely iterate and modify collections to avoid exceptions and race conditions, developing skills essential for technical interviews and real-world development.

We'll cover the following...

The Java collections framework (JCF) provides standard collection types and algorithms. Technical interviews often test when to use each collection type and how to iterate over collections safely.

Let’s explore the core types, thread-safety mechanisms, and iteration rules.

AI Powered
Saved
10 attempts left
Reset
Question

What are legacy collections?

You have 10 attempts to answer.
AI Powered
Saved
10 attempts left
Reset
Question

What is the collections framework?

You have 10 attempts to answer.
AI Powered
Saved
10 attempts left
Reset
Question

What are wrapped collections, and does wrapping a collection always make it thread-safe?

You have 10 attempts to answer.

Let’s look at an example of faulty code that requires client-side synchronization to prevent race conditions.

Java
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
class Program {
    public static void main(String[] args) {
        List<Integer> myList = new ArrayList<>();
        List<Integer> syncList = Collections.synchronizedList(myList);
        if (syncList.isEmpty()) {
            syncList.add(1);
        }
    }
}

  • Line 8: We wrap the standard ArrayList ...