Capgemini Production Support Analyst Interview Questions, Process, and Tips

HashMap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where the pair will be stored.

• If multiple key-value pairs hash to the same index, they are stored in a linked list at that index.

• To retrieve a value...read more

HashMap is not thread-safe while ConcurrentHashMap is thread-safe.

• HashMap is not thread-safe and can lead to ConcurrentModificationException if modified while iterating.

• ConcurrentHashMap allows concurrent modifications without the need for external synchronization.

• ConcurrentHashMap achieves thread-safety by dividing the map into segments, allowing multiple threads to operate on different segments concurrently.

• Concurren...read more

No, main method in Java cannot be overridden.

• Main method is a static method of a class and cannot be overridden.

• Subclasses can have their own main method, but it will not be considered as the entry point of the program.

• Example: public class SubClass extends MainClass { public static void main(String[] args) { // This is not the entry point of the program }}

Use the 'ls' command with the '-a' flag to find hidden files in Unix.

• Use the command 'ls -a' to list all files, including hidden files.

• Hidden files in Unix start with a dot (.) before the file name.

• Example: 'ls -a' will display all files, including hidden files.

Use the sed command to replace a string in Unix

• Use the following syntax: sed 's/original_string/new_string/g' filename

• The 's' flag stands for substitute, 'g' flag stands for global (replace all occurrences)

• Example: sed 's/hello/goodbye/g' file.txt