Klaus IT Solutions Senior Oracle Database Administrator Interview Questions and Answers

Angular is a popular front-end framework for building web applications.

• Angular is developed and maintained by Google.

• It uses TypeScript for building scalable and maintainable applications.

• Angular has a powerful CLI for generating components, services, and more.

• It has a large and active community with many third-party libraries and plugins available.

• Angular has a modular architecture that allows for easy code reuse and

The '==' operator compares the reference of objects, while the 'equals' method compares the content of objects.

• The '==' operator checks if two objects refer to the same memory location.

• The 'equals' method compares the content of objects based on their implementation.

• The 'equals' method can be overridden to provide custom comparison logic.

• Example: String str1 = new String('hello'); String str2 = new String('hello'); str...read more

JIT compiler stands for Just-In-Time compiler. It dynamically compiles code during runtime for improved performance.

• JIT compiler translates bytecode into machine code at runtime

• It optimizes code execution by identifying frequently executed code and compiling it

• Examples include the JIT compilers used in Java Virtual Machine (JVM) and .NET Common Language Runtime (CLR)

Assigning another value to a string reference creates a new string object in memory.

• Assigning a new value to a string reference creates a new string object in memory

• The original string object remains unchanged

• The new value is stored in a different memory location

• The old value may be garbage collected if there are no other references to it

The finally block will always execute, even if an exception is thrown from the try block.

• The finally block is used to execute code that should always run, regardless of whether an exception is thrown or not.

• If an exception is thrown from the try block, the code in the finally block will still execute.

• This is useful for cleaning up resources, such as closing files or database connections.

• Example: try { // code that may ...read more

Serialization is the process of converting an object into a stream of bytes to store or transmit it.

• Java provides Serializable interface to enable serialization of objects.

• Serialization can be used for caching, deep cloning, and remote method invocation.

• Deserialization is the process of converting a stream of bytes back into an object.

• Java also provides Externalizable interface for custom serialization.

• Serialization ca...read more

Fail fast and fail safe are two error handling techniques in Java.

• Fail fast approach detects errors as early as possible and stops the program execution immediately.

• Fail safe approach handles errors gracefully and continues program execution.

• Examples of fail fast include NullPointerException and ArrayIndexOutOfBoundsException.

• Examples of fail safe include using try-catch blocks and logging errors instead of throwing ex

Lambda expression is an anonymous function while method reference refers to an existing method

• Lambda expression is used to create an instance of a functional interface

• Method reference is used to refer to an existing method of a class or object

• Lambda expression uses the arrow operator (->) to separate the parameters and the body

• Method reference uses the double colon (::) operator to separate the class or object and the

Sleep pauses the execution of a thread for a specified time, while wait pauses the execution until a specific condition is met.

• Sleep is a static method of the Thread class, while wait is an instance method of the Object class.

• Sleep is used to introduce a delay in the execution of a thread, while wait is used to wait for a specific condition to be met.

• Sleep releases the lock on the object, while wait does not release th...read more

To get unique values from a collection using stream, use the distinct() method.

• Call the distinct() method on the stream of the collection.

• The distinct() method returns a stream of unique elements.

• Use the collect() method to convert the stream back to a collection.

Concurrent hashmap allows multiple threads to access and modify the map concurrently.

• Concurrent hashmap is thread-safe and uses internal locking mechanisms to ensure consistency.

• It uses a technique called 'lock striping' to divide the map into multiple segments, each with its own lock.

• This allows multiple threads to access different segments of the map concurrently without blocking each other.

• Concurrent hashmap also us...read more

Hashmap and Hashset are data structures used to store key-value pairs and unique values respectively.

• Hashmap uses hashing to store key-value pairs in an array. The hash function is used to map the key to an index in the array.

• Hashset is similar to Hashmap but only stores unique values. It uses hashing to store values in an array.

• Both Hashmap and Hashset have constant time complexity for insertion, deletion, and retriev...read more

ConcurrentHashMap is a thread-safe implementation of the Map interface in Java.

• It allows multiple threads to access and modify the map concurrently without any external synchronization.

• It achieves this by dividing the map into segments, each of which can be locked independently.

• It provides better performance than synchronized HashMap for concurrent access.

• It is part of the java.util.concurrent package in Java.

• Example: ...read more

Iterator is a general interface while ListIterator is specific to List interface.

• Iterator can traverse any collection while ListIterator can traverse only List.

• ListIterator can traverse in both directions while Iterator can traverse only forward.

• ListIterator has additional methods like add(), set(), previous(), etc.

• Iterator is used for read-only access while ListIterator is used for both read and write access.