Java MCQ questions with answers

Practice Java MCQ questions with answers on core syntax, collections, exceptions, multithreading, and JVM concepts.

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Java MCQ questions with answers

Which option correctly describes the relationship among JDK, JRE, and JVM?

Java source code is compiled into:

Java is not considered a purely object-oriented language mainly because:

Which of the following is the wrapper class for `int`?

Java argument passing is:

Objects created using `new` are generally stored in:

What is the primary role of a classloader in Java?

Why is the `main` method declared as `static` in Java?

Which option correctly matches the term with its purpose?

Autoboxing means:

Which statement about Java `String` is correct?

What is true for two identical string literals in Java?

For strings in Java, `equals()` checks:

Which class should generally be preferred for repeated string modification in a single-threaded context?

Which statement about `StringBuffer` is correct?

What does `intern()` return for a string?

Why is `String` often a good key in `HashMap`?

For repeated concatenation inside a loop, which choice is usually best?

Why might `char[]` be preferred over `String` for passwords?

What is the result of `new String("java") == "java"`?

A checked exception in Java is one that:

Which of the following is an unchecked exception?

Which statement correctly compares `throw` and `throws`?

Which block usually runs whether or not an exception occurs?

Try-with-resources works best with objects that implement:

A custom checked exception is usually created by extending:

Which catch order is valid?

If both `try` and `finally` contain `return` statements, which one wins?

Which statement about `Error` in Java is correct?

Which statement about multi-catch in Java is correct?

Which statement about `Map` is correct?

Which collection type preserves insertion order and allows duplicates?

Which collection type is mainly used when duplicate elements should be avoided?

Which statement about `ArrayList` is most accurate?

Compared to `ArrayList`, `LinkedList` is usually better when:

Which statement about `HashMap` is correct?

How does `Hashtable` differ from `HashMap`?

Which set implementation keeps elements in sorted order?

Which interface allows bidirectional traversal of list elements?

A fail-fast iterator usually reacts to structural modification by throwing:

What is the main benefit of Java generics?

Using a raw type such as `List` instead of `List<String>` mainly causes:

Type erasure in Java means:

Which wildcard is usually preferred when a structure mainly produces values of type `T`?

Which wildcard is usually preferred when a structure mainly consumes values of type `T`?

What is the main purpose of an enum in Java?

A lambda expression in Java is mainly used with:

A functional interface must contain:

What is the main advantage of the Stream API?

Why is `Optional` useful in Java APIs?

What is the difference between calling `start()` and calling `run()` on a thread object?

Which statement about `wait()` is correct?

Which statement about `sleep()` is correct?

The `synchronized` keyword mainly provides:

What is the main purpose of `volatile` in Java?

Which statement about daemon threads is correct?

Why is implementing `Runnable` often preferred over extending `Thread`?

What happens if the same `Thread` object is started twice?

What is the main purpose of JIT compilation in Java?

A static synchronized method locks on:

Java MCQ questions with answers

Which option correctly describes the relationship among JDK, JRE, and JVM?

Java source code is compiled into:

Java is not considered a purely object-oriented language mainly because:

Which of the following is the wrapper class for `int`?

Java argument passing is:

Objects created using `new` are generally stored in:

What is the primary role of a classloader in Java?

Why is the `main` method declared as `static` in Java?

Which option correctly matches the term with its purpose?

Autoboxing means:

Which statement about Java `String` is correct?

What is true for two identical string literals in Java?

For strings in Java, `equals()` checks:

Which class should generally be preferred for repeated string modification in a single-threaded context?

Which statement about `StringBuffer` is correct?

What does `intern()` return for a string?

Why is `String` often a good key in `HashMap`?

For repeated concatenation inside a loop, which choice is usually best?