Softenger Trainee Interview Questions and Answers

Java is a high-level programming language known for its platform independence and object-oriented approach.

• Java is widely used for developing desktop, web, and mobile applications.

• It is known for its write once, run anywhere (WORA) capability.

• Java uses a virtual machine (JVM) to execute code, providing portability across different operating systems.

• It supports multithreading, exception handling, and dynamic memory allo...read more

Inheritance is a mechanism in object-oriented programming where a new class is created from an existing class.

• Allows for code reuse and promotes code organization

• The new class (subclass) inherits properties and methods from the existing class (superclass)

• Subclass can add new properties and methods or override existing ones

• Example: A Car class can inherit properties and methods from a Vehicle class

This interview question covers various topics including programming, design patterns, data structures, and exception handling in Java.

• Write a program to generate the Fibonacci series

• Write a program using boolean variables

• Explain the ClassCastException and how to handle it

• Discuss the Singleton design pattern and its implementation with different JDK versions

• Explain abstract classes and interfaces in your current project

• ...read more

Encapsulation is the process of hiding implementation details and providing access to only necessary information.

• Encapsulation helps in achieving data abstraction and information hiding.

• It allows for better control over data and prevents unauthorized access.

• In Java, encapsulation is achieved through the use of access modifiers such as private, public, and protected.

• For example, a class may have private variables that c...read more

A string is a sequence of characters used to represent text in programming.

• Strings are often used for storing and manipulating text data.

• In Java, strings are represented by the String class.

• Strings can be concatenated using the + operator.

• Strings are immutable, meaning they cannot be changed once created.

• Examples of string literals include "hello world" and "42".

Autoboxing is the automatic conversion of primitive data types to their corresponding object wrapper classes.

• Autoboxing is useful when working with collections that require objects instead of primitives.

• Example: int i = 5; Integer j = i; //autoboxing

• Unboxing is the opposite of autoboxing, where an object of a wrapper class is converted back to its corresponding primitive type.

• Example: Integer j = 5; int i = j; //unboxi

Typecasting up and down refers to converting a variable of one data type to another data type of higher or lower precision.

• Typecasting up involves converting a variable of lower precision to a variable of higher precision, such as converting an int to a double.

• Typecasting down involves converting a variable of higher precision to a variable of lower precision, such as converting a double to an int.

• Typecasting can resul...read more

To iterate a map in Java, use a for-each loop or an iterator.

• Use the entrySet() method to get a set of key-value pairs

• For-each loop: for(Map.Entry entry : map.entrySet())

• Iterator: Iterator> iterator = map.entrySet().iterator();

• Use hasNext() and next() methods to iterate through the map

Types of synchronization in Java

• Synchronized methods

• Synchronized statements

• ReentrantLock

• Semaphore

• CountDownLatch

Access modifiers in method overriding

• Access modifiers in the overriding method cannot be more restrictive than the overridden method

• The access modifier can be less restrictive or the same as the overridden method

• Private methods cannot be overridden

• Examples: public method can be overridden by public or protected method, but not by private method