Q1) Attempt any Eight : [8 × 2 = 16]
1.What is
Java? Why Java is a platform neutral language?
1)Java is a high-level, object-oriented programming language that was
developed by Sun Microsystems.
2)It was designed to be platform-independent, allowing developers to
write code once and run it on any device or operating system that has a Java
Virtual Machine (JVM) installed.
3)Java is Platform neutral because the same Java code will run on
multiple platforms
2.What is
access specifiers? List them.
There are four types of Java access modifiers:
1.Private: The access level of a private modifier is only within the
class. It cannot be accessed from outside the class.
2.Default: The access level of a default modifier is only within the
package. It cannot be accessed from outside the package. If you do not specify
any access level, it will be the default.
3.Protected: The access level of a protected modifier is within the
package and outside the package through child class. If you do not make the
child class, it cannot be accessed from outside the package.
4.Public: The access level of a public modifier is everywhere. It can be
accessed from within the class, outside the class, within the package and
outside the package.
3.Define
Keyword-Static.
The static keyword in Java is used for memory management mainly. We can
apply static keyword with variables, methods, blocks and nested classes. The
static keyword belongs to the class than an instance of the class.
The static can be:
1.Variable (also known as a class variable)
2.Method (also known as a class method)
3.Block
4.Nested class
4.Why we set
environment variable in Java?
We set environment variables in
Java for:
1.Configuration: To store settings like database connections, API keys,
and environment-specific values.
2.Security: To protect sensitive information like passwords and API
tokens.
3.Portability: To make applications easily adaptable to different
environments.
4.Dynamic Configuration: To change application settings without code
changes.
5.Third-Party Integration: To configure interactions with external
services and libraries.
6.Compliance and Auditing: To adhere to security and regulatory
requirements.
7.Ease of Maintenance: To manage and update settings conveniently.
To access environment variables in Java, you typically use the
System.getenv() method to retrieve their values. Environment variables can be
set at the operating system level or by various deployment tools and platforms
(e.g., Docker, Kubernetes, Heroku) to provide configuration to your Java
application.
5.Write
advantages of Inheritance.
•Another advantages of inheritance is extensibility, you can add new
features or change the existing features easily in subclasses.
•Using inheritance we can achieve runtime polymorphism(method
overriding).
•Inheritance makes easy to maintain the code, as the common codes are
written at one place.
•The most important use of inheritance in Java is code reusability. The
code that is present in the parent class can be directly used by the child
class.
•Method overriding is also known as runtime polymorphism. Hence, we can
achieve Polymorphism in Java with the help of inheritance.
6.Define class and object with
one example.
•Object − Objects have states and behaviors. Example: A dog has states -
color, name, breed as well as behaviors – wagging the tail, barking, eating. An
object is an instance of a class.
•Class − A class can be defined as a template/blueprint that describes
the behavior/state that the object of its type support.
•An object is called an instance of a class. For example, suppose Bicycle
is a class then MountainBicycle, SportsBicycle, TouringBicycle, etc can be
considered as objects of the class.
•Creating an Object in Java
Bicycle sportsBicycle = new Bicycle();
Bicycle touringBicycle = new Bicycle();
Creating a class in Java
class Bicycle {
private int gear = 5;
// behavior or method
public void braking() {
System.out.println("Working of Braking");
}
}
7.What is
Swing?
Java Swing is a part of Java Foundation Classes (JFC) that is used to
create window-based applications. It is built on the top of AWT (Abstract
Windowing Toolkit) API and entirely written in java.
Unlike AWT, Java Swing provides platform-independent and lightweight
components.
The javax.swing package provides classes for java swing API such as
JButton, JTextField, JTextArea, JRadioButton, JCheckbox, JMenu, JColorChooser
etc.
8.When
buffered reader is used?
BufferedReader
is a class in Java that
is used for reading text from character input streams with improved efficiency
and performance.
Reading Text
Files: When
you want to read data from a text file, you can use BufferedReader to read
lines of text efficiently. It's commonly used in file input operations.
try (BufferedReader br = new BufferedReader(new
FileReader("example.txt"))) { String line; while ((line =
br.readLine()) != null) { // Process each line of text } } catch (IOException
e) { e.printStackTrace(); }
9.What is
main difference between exception and error?
Error
1.An error cannot be handled at runtime.
2.An error can occur both at compile time and during runtime.
3.There are 3 types of Errors: Syntax Error, Runtime Error and Logical
Error
4.An Error is such an event that no one can control or guess when it is
going to happen.
Exception
1.An exception can be handled at runtime
2.Although all the Exceptions occur at runtime. But checked Exceptions
can be detected at compile time.
3.There are 2 types of Exceptions: Checked Exceptions and Unchecked Exceptions
4.An exception has the capacity to distract the normal flow of the
program and change its direction to somewhere else when an exceptional case has
occurred.
5.An Exception can be guessed, handled, and utilized in order to change
the original flow of the program.
10.What is
Panel?
Panel is the simplest container class. A panel provides space in which an
application can attach any other component, including other panels.
11.What is
JDK? How to build and run java program?
The Java Development Kit (JDK) is a software development environment that
offers a collection of tools and libraries necessary for developing Java
applications. You need the JDK to convert your source code into a format that
the Java Runtime Environment (JRE) can execute.
We must follow the steps given below to run a Java program.
Open the notepad and write a Java program into it.
Save the Java program by using the class name followed by .java
extension.
Open the CMD, type the commands and run the Java program.
class Simple{
public static void main(String
args[]){
System.out.println("Hello
Java");
}
}
To compile: javac Simple.java
To execute: java Simple
Output: Hello Java
12.What is
use of classpath?
The classpath in Java specifies where the Java Virtual Machine (JVM)
should look for classes and libraries when running a Java program. It ensures
that the JVM can locate and load the necessary classes and resources for the
program to execute correctly.
13.What is
collection? Explain collection frame work in details.
A collection is an object that can hold references to other objects. The
collection interfaces declare the operations that can be performed on each type
of collection.
The Collection in Java is a framework that provides an architecture to
store and manipulate the group of objects.
Java Collections can achieve all the operations that you perform on a
data such as searching, sorting, insertion, manipulation, and deletion.
A Collection represents a single unit of objects, i.e., a group.
The Collection framework represents a unified architecture for storing
and manipulating a group of objects. It has:
Interfaces and its implementations, i.e., classes
Algorithm
14.What is
the use of Reader and Writer class?
In Java, the Reader and Writer classes are used for character stream
input and output operations, respectively. They are designed to handle
character data, making them suitable for reading and writing text-based
information, such as files, network streams, or user input/output. These classes
provide methods for reading and writing characters, making them essential for
text-based I/O tasks.
15.What is
the use of layout manager?
The Layout managers enable us to control the way in which visual
components are arranged in the GUI forms by determining the size and position
of components within the containers.
Layout managers help you create flexible and platform-independent GUIs by
handling the placement and resizing of components automatically. Common layout
managers in Java include FlowLayout, BorderLayout, GridLayout, and
GridBagLayout, each offering different ways to organize and control the
placement of components within a container.
16.What is
difference between paint ( ) and repaint ( ).
paint()
The paint() method is called when some action is performed on the window.
This method supports painting via graphics object.
repaint()
Whenever a repaint method is called, the update method is also called
along with paint() method.
This method is used to cause paint() to be invoked by the AWT painting
thread.
17.Define
keyword throw.
The throw keyword in Java is used to explicitly throw an exception from a
method or any block of code. We can throw either checked or unchecked exception
18.Define
polymorphism.
Polymorphism is the ability of an object to take on many forms. The most
common use of polymorphism in OOP occurs when a parent class reference is used
to refer to a child class object.
