10+ Varun Agro Processing Foods Interview Questions and Answers

The new operator is used to create an instance of a class or to allocate memory for an object.

• The new operator is followed by the name of the class and parentheses.

• It can also be used to create arrays of objects.

• Example: MyClass obj = new MyClass();

• Example: int[] arr = new int[5];

JVM stands for Java Virtual Machine. It is an abstract machine that provides a runtime environment for Java programs.

• JVM interprets compiled Java code and executes it

• It provides platform independence by converting bytecode to machine-specific code

• JVM manages memory allocation and garbage collection

• Examples of JVM implementations include Oracle JVM, OpenJDK, and IBM JVM

Hashmap is a data structure that stores key-value pairs and uses hashing to retrieve values quickly.

• Hashmap uses a hash function to convert the key into an index in an array.

• Collisions can occur when two keys map to the same index, which is resolved using separate chaining or open addressing.

• Hashmap provides constant time complexity O(1) for insertion, deletion, and retrieval of values.

• Java's Hashmap implementation uses an array of linked lists to handle collisions.

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String is immutable to ensure thread safety and prevent unintended modification.

• Immutable objects are safer to use in multi-threaded environments as they cannot be changed by other threads.

• String pool is possible because of immutability, which saves memory and improves performance.

• StringBuffer and StringBuilder classes are used for mutable string operations.

• Example: String s = "hello"; s.concat(" world"); // returns a new string, s remains unchanged.

List allows duplicate elements and maintains insertion order, while Set does not allow duplicates and does not maintain order.

• List can contain duplicate elements, Set cannot

• List maintains insertion order, Set does not guarantee order

• List is implemented by classes like ArrayList, LinkedList, Set is implemented by classes like HashSet, TreeSet

• Example: List list = new ArrayList<>(); Set set = new HashSet<>();