Mintoak Innovations Java Developer Interview Questions, Process, and Tips

HashMap in Java is a data structure that stores key-value pairs and allows fast retrieval of values based on keys.

• HashMap is part of the Java Collections framework.

• It uses hashing to store key-value pairs, allowing for fast retrieval.

• Keys in a HashMap must be unique, but values can be duplicated.

• Example: HashMap<String, Integer> map = new HashMap<>(); map.put("John", 25);

A constructor in Java is a special type of method that is used to initialize objects. It has the same name as the class and no return type.

• Constructors are called when an object of a class is created.

• They can be used to initialize instance variables or perform any other setup required for the object.

• Constructors can be overloaded, meaning a class can have multiple constructors with different parameters.

• If a class does ...read more

You can sort a class object by implementing the Comparable interface and overriding the compareTo method.

• Implement the Comparable interface in the class and override the compareTo method to compare objects based on roll number.

• Use Collections.sort() method to sort the list of objects based on roll number.

• Example: class Student implements Comparable<Student> { public int compareTo(Student s) { return this.rollNo -

A Comparator in Java is an interface used to compare objects for sorting purposes.

• Comparator interface is used to define custom comparison logic for objects.

• It has a method called compare() which takes two objects as arguments and returns an integer value based on their comparison.

• It is commonly used with sorting algorithms like Collections.sort() or Arrays.sort().

Functional interfaces in Java are interfaces with a single abstract method, used for lambda expressions and method references.

• Functional interfaces have only one abstract method, but can have multiple default or static methods.

• Examples include java.lang.Runnable, java.util.Comparator, and java.util.function.Predicate.

• Functional interfaces can be used with lambda expressions and method references for concise code.

Spring Boot annotations are used to simplify the development process by providing metadata to the Spring framework.

• Annotations like @RestController, @RequestMapping, and @Autowired are commonly used in Spring Boot to define controllers, request mappings, and dependency injection.

• Annotations like @SpringBootApplication are used to bootstrap the Spring application context.

• Annotations like @ComponentScan and @EnableAutoCo...read more

Streams in Java are sequences of elements that support functional-style operations.

• Streams are used to process collections of objects in a functional way.

• They allow for concise and readable code by enabling operations like filter, map, reduce, etc.

• Example: List names = Arrays.asList("Alice", "Bob", "Charlie"); Stream stream = names.stream();