GeoControl Systems Inc Interview Questions and Answers

ArrayList uses dynamic arrays, while LinkedList uses doubly linked nodes for storage and access.

• ArrayList provides fast random access (O(1)) due to its underlying array structure.

• LinkedList allows for efficient insertions and deletions (O(1)) at both ends and in the middle.

• ArrayList has a fixed size, requiring resizing (O(n)) when capacity is exceeded, while LinkedList grows dynamically.

• Example: Use ArrayList for frequ...read more

Java's synchronized keyword offers thread safety but has limitations compared to ReentrantLock.

• Advantages of synchronized: Simple to use and understand.

• Disadvantages of synchronized: Can lead to thread contention and performance issues.

• ReentrantLock allows more flexibility, such as tryLock() and timed lock attempts.

• ReentrantLock can be used for fair locking, preventing thread starvation.

• Synchronized blocks are tied to ...read more

In Java, '==' checks reference equality, while '.equals()' checks value equality. Use them appropriately to avoid bugs.

• == compares object references, checking if both point to the same memory location.

• Example: String a = new String('test'); String b = new String('test'); a == b returns false.

• .equals() compares the actual content of the objects.

• Example: a.equals(b) returns true because the content is the same.

• Use '==' f...read more

Java 8 introduced lambdas, Stream API, and other features that enhance functional programming and simplify code.

• Lambdas: Enable concise representation of functional interfaces. Example: (x, y) -> x + y.

• Stream API: Facilitates functional-style operations on collections. Example: list.stream().filter(x -> x > 10).collect(Collectors.toList()).

• Default Methods: Allow adding new methods to interfaces without breakin...read more

Checked exceptions must be declared or handled, while unchecked exceptions do not require explicit handling.

• Checked exceptions are subclasses of Exception but not of RuntimeException.

• Example: IOException, SQLException are checked exceptions.

• Unchecked exceptions are subclasses of RuntimeException.

• Example: NullPointerException, ArrayIndexOutOfBoundsException are unchecked exceptions.

• Checked exceptions must be caught or d...read more

The Java Memory Model defines how threads interact through memory, ensuring visibility and ordering of shared variables.

• The Java Memory Model (JMM) specifies how threads interact with memory, ensuring consistency and visibility.

• It defines rules for visibility, atomicity, and ordering of operations in a multithreaded environment.

• Synchronization mechanisms (like synchronized blocks) ensure that only one thread can access...read more

Method overloading allows multiple methods with the same name but different parameters; overriding redefines a method in a subclass.

• Method Overloading: Same method name, different parameters (type, number, or both).

• Example of Overloading: 'void add(int a, int b)' and 'void add(double a, double b)'.

• Use Overloading for convenience and readability when methods perform similar functions.

• Method Overriding: Redefining a meth...read more