What is Scheduler ?

Schedulers A schedule is a decision maker that selects the processes from one scheduling queue to another or allocates CPU for execution. The Operating System has three types of scheduler: Long-term scheduler or Job scheduler Short-term scheduler or CPU scheduler Medium-term scheduler   Long-term scheduler or Job scheduler The long-term scheduler or job scheduler selects… Continue reading What is Scheduler ?

What is private constructor ,Factory method and Singleton class in JAVA ?

Factory Method:- If the return type of method is class name then it is known as the Factory method. Private constructor defining a “virtual” constructor. Private Constructor:- The factory constructor declared with private-keyword is known as private-constructor. If the constructor is private we cannot create an object outside class. The private constructor is used to serve… Continue reading What is private constructor ,Factory method and Singleton class in JAVA ?

What is Process Scheduling Queues in Operating System?

Process Scheduling Queues:-  Process scheduling is an essential part of a Multiprogramming operating systems. It contains various operation such as:- Job Queue: It contains the process entered into the system for execution. This queue consists of all processes in the system; those processes are entered into the system as a new process Ready Queue:   Ready… Continue reading What is Process Scheduling Queues in Operating System?

What is Process Control Block (PCB) in Operating System ?

Process Control Block (PCB) In the operating system, Process Control Block contains the information about the process which manages the scheduling of a particular process.  Process state  Program counter  CPU registers  CPU scheduling information  Memory-management information  Accounting information  I/O status information Process state: The state may be new, ready, running, waiting, halted, and SO on.… Continue reading What is Process Control Block (PCB) in Operating System ?

Hardware Protection

Hardware Protection Dual-Mode Operation I/O Protection Memory Protection CPU Protection Dual-Mode Operation Sharing system resources require the operating system to ensure that an incorrect program cannot cause other programs to execute incorrectly. Provide hardware support to differentiate between at least two modes of operations. User mode – execution is done on behalf of a user.… Continue reading Hardware Protection

What is process in Operating System ?

Process Concept:- The process is the running program of the system. Linux and Windows both are the multi-processes operating system. The program doesn’t allocate memory but process allocate memory. Every process allocates 4GB virtual memory. The process is two types: –1)parent process 2) the Child process. The process which is created another process is called… Continue reading What is process in Operating System ?

What is Abstract class and Anonymous class in java…?

Abstract and Anonymous class:- Abstract class:- If the class name is declared as an abstract keyword it is known as abstract class. An abstract class may or may not contain an abstract method. Abstract class and anonymous class almost equivalent to using a named inner class. If the class is abstract it cannot be instantiated(we… Continue reading What is Abstract class and Anonymous class in java…?

What are the services provided by the Operating-System…?

Operating System Services Following are the five services provided by operating systems to the convenience of the users. Program Execution The purpose of computer systems is to allow the user to execute programs. So the operating system provides an environment where the user can conveniently run programs. Running a program involves the allocating and deallocating… Continue reading What are the services provided by the Operating-System…?

what is System call ?

System Call: System calls provide an interface between the processor and the operating system. System calls allow user-level processes to request some services from the operating system which process itself is not allowed to do. For example, for I/O a process involves a system call telling the operating system to read or write a particular… Continue reading what is System call ?

How to create the Object of Abstract class…?

How to create the object of abstract class..? We can create the Object of Abstract class by two different ways. 1)By inheritance Access the resources of the .class file after establish the relation is the concept of inheritance in java. Inheritance is the object-oriented concept which is used to create a relation between two .class… Continue reading How to create the Object of Abstract class…?

Difference between constructor and method

Difference between method and constructor The following are the difference between method and constructor. Method name may or may not be the same as the class name whereas the constructor name must be same as the class name. A method should have a return type in java where are constructor never returns any value, so… Continue reading Difference between constructor and method

Constructor in JAVA

  CONSTRUCTOR IN JAVA:- The constructor in Java is very similar to the method. The main job of the constructor is to initialize the object. The constructor is a block of code that initializes the newly created object. A constructor is called automatically when a new instance of an object is created. Each and every… Continue reading Constructor in JAVA

Variable or data member in java

Variable/Data member:- The variable or data member in java is a block of memory which can store a data value. In Java, all the variable should be declared before they can be used. Java support 6 types of variable Local Variable Static Variable Non-static Variable Final Variable Transient Variable Volatile Variable Local Variable The variable… Continue reading Variable or data member in java

Class in java ?

Class:- Class in Java is the selection of similar types of object. From one class we can create n number f objects and n number of objects getting together to make a class. A class is declared using class keyword. Pro-grammatically class is nothing but a keyword which is used to declare any user-defined class. It is… Continue reading Class in java ?