Interview Questions

File[] listFiles();

this method returns list of files stored in a directory.

API stands for Application programming interface is very useful in cloud platforms as it allows easy implementation of it on the system. It removes the need to write full fledged programs. It provides the instructions to make the communication between one or more applications. It also allows easy to create application with ease and link the cloud services with other systems.

A thread is a lightweight subprocess, a smallest unit of processing. It is a separate path of execution. It shares the memory area of process.

As shown in the above figure, thread is executed inside the process. There is context-switching between the threads. There can be multiple processes inside the OS and one process can have multiple threads.

Autoboxing is the process of converting a primitive type data into its corresponding wrapper class object instance.

Example:

Integer number = new Integer (100); // number is now refers to the object 100

Unboxing is the process of converting a wrapper instance into a primitive type.

Example: 

Integer number = new Integer (100); 

int num = number;// without type casting number would be changed into int type

If the price of a product rises, the demand for the substitute product increases.

An abstract class is an incomplete class. An abstract class is defined with the keyword abstract . We cannot create an object of the abstract class because it is not complete. It sets a behavioral protocol for all its child classes.

1. Initialization
2. At selection-screen
3. Start-of-selection
4. End-of-selection
5. Top-of-page
6. End-of-page
7. At line-selection
8. At user-command
9. At PF
10. Get
11. At New
12. At LAST
13. AT END
14. AT FIRST

By using overloading we can add new functionality to the sub class.