This document provides an overview of key Java concepts including:
1. Comments in Java code use C++-style syntax with /* */ for multi-line comments and // for single-line comments.
2. Classes define the structure and behavior of objects through fields that represent data and methods that represent operations.
3. Inheritance allows subclasses to extend existing classes to reuse and modify their behavior through mechanisms like overriding methods.
OOPS Concepts, Java Evolution, Class Object basic, Class Object Constructor overloading, Inheritance, Array and String, Final Abstract class and interfaces, Exceptions, Streams, GUI Applications, Applet Programming, Network Programming and Java Sockets, Multi Threading
OOPS Concepts, Java Evolution, Class Object basic, Class Object Constructor overloading, Inheritance, Array and String, Final Abstract class and interfaces, Exceptions, Streams, GUI Applications, Applet Programming, Network Programming and Java Sockets, Multi Threading
Java OOP Programming language (Part 3) - Class and ObjectOUM SAOKOSAL
Java OOP Programming language (Part 3) - Class and Object
Oum Saokosal
Where to me find me more:
YouTube: https://www.youtube.com/user/oumsaokosal
FB Page: https://facebook.com/kosalgeek
PPT: https://www.slideshare.net/oumsaokosal
Twitter: https://twitter.com/okosal
Web: http://kosalgeek.com
Lara Technologies are providing Software Training Division, Java/J2ee, Android, Web Services, Logical Coding, Basics Of C Language, Soft Skills, Aptitude, Etc.
Method overloading, recursion, passing and returning objects from method, new...JAINAM KAPADIYA
Method and Method overloading
How to overload method in JAVA?
Method overloading Examples of the program.
New operator
Recursion
Passing and returning objects from methods.
Java OOP Programming language (Part 3) - Class and ObjectOUM SAOKOSAL
Java OOP Programming language (Part 3) - Class and Object
Oum Saokosal
Where to me find me more:
YouTube: https://www.youtube.com/user/oumsaokosal
FB Page: https://facebook.com/kosalgeek
PPT: https://www.slideshare.net/oumsaokosal
Twitter: https://twitter.com/okosal
Web: http://kosalgeek.com
Lara Technologies are providing Software Training Division, Java/J2ee, Android, Web Services, Logical Coding, Basics Of C Language, Soft Skills, Aptitude, Etc.
Method overloading, recursion, passing and returning objects from method, new...JAINAM KAPADIYA
Method and Method overloading
How to overload method in JAVA?
Method overloading Examples of the program.
New operator
Recursion
Passing and returning objects from methods.
Core java training in Bangalore is one the best Training in Entire bangalore, Where you can learn Java in Shorter time. TIB Academy is the platform where you gain all you confidence back.
Myassignmenthelpers.com is an Online service provider for Java assignments & homework problems. Our online experts provide Java Assignment help & Java homework help with aims to help college students across the globe. Our writers provide you unique data along with a plagiarised report so that you can ensure that your data is unique. Our writers are available 24*7. Please send your complete requirements at support@myassignmenthelpers.com or else attach on the website. You can also discuss the requirements with our chat agent.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Search and Society: Reimagining Information Access for Radical FuturesBhaskar Mitra
The field of Information retrieval (IR) is currently undergoing a transformative shift, at least partly due to the emerging applications of generative AI to information access. In this talk, we will deliberate on the sociotechnical implications of generative AI for information access. We will argue that there is both a critical necessity and an exciting opportunity for the IR community to re-center our research agendas on societal needs while dismantling the artificial separation between the work on fairness, accountability, transparency, and ethics in IR and the rest of IR research. Instead of adopting a reactionary strategy of trying to mitigate potential social harms from emerging technologies, the community should aim to proactively set the research agenda for the kinds of systems we should build inspired by diverse explicitly stated sociotechnical imaginaries. The sociotechnical imaginaries that underpin the design and development of information access technologies needs to be explicitly articulated, and we need to develop theories of change in context of these diverse perspectives. Our guiding future imaginaries must be informed by other academic fields, such as democratic theory and critical theory, and should be co-developed with social science scholars, legal scholars, civil rights and social justice activists, and artists, among others.
Let's dive deeper into the world of ODC! Ricardo Alves (OutSystems) will join us to tell all about the new Data Fabric. After that, Sezen de Bruijn (OutSystems) will get into the details on how to best design a sturdy architecture within ODC.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
2. UMBC CMSC 331 Java 2
Comments are almost like C++
The javadoc program generates HTML API documentation
from the “javadoc” style comments in your code.
/* This kind of comment can span multiple lines */
// This kind is to the end of the line
/**
* This kind of comment is a special
* ‘javadoc’ style comment
*/
3. UMBC CMSC 331 Java 3
An example of a class
class Person {
String name;
int age;
void birthday ( ) {
age++;
System.out.println (name +
' is now ' + age);
}
}
Variable
Method
4. UMBC CMSC 331 Java 4
Scoping
• As in C/C++, scope is determined by the placement of curly braces {}.
• A variable defined within a scope is available only to the end of that
scope.
{ int x = 12;
/* only x available */
{ int q = 96;
/* both x and q available */
}
/* only x available */
/* q “out of scope” */
}
{ int x = 12;
{ int x = 96; /* illegal */
}
}
This is ok in C/C++ but not in Java.
5. UMBC CMSC 331 Java 5
An array is an object
• Person mary = new Person ( );
• int myArray[ ] = new int[5];
• int myArray[ ] = {1, 4, 9, 16, 25};
• String languages [ ] = {"Prolog",
"Java"};
• Since arrays are objects they are allocated dynamically
• Arrays, like all objects, are subject to garbage collection
when no more references remain
– so fewer memory leaks
– Java doesn’t have pointers!
6. UMBC CMSC 331 Java 6
Scope of Objects
• Java objects don’t have the same lifetimes as
primitives.
• When you create a Java object using new, it hangs
around past the end of the scope.
• Here, the scope of name s is delimited by the {}s
but the String object hangs around until GC’d
{
String s = new String("a string");
} /* end of scope */
7. UMBC CMSC 331 Java 7
Methods, arguments and return values
• Java methods are like C/C++ functions. General case:
returnType methodName ( arg1, arg2, … argN) {
methodBody
}
The return keyword exits a method optionally with a value
int storage(String s) {return s.length() * 2;}
boolean flag() { return true; }
float naturalLogBase() { return 2.718f; }
void nothing() { return; }
void nothing2() {}
8. UMBC CMSC 331 Java 8
The static keyword
• Java methods and variables can be declared static
• These exist independent of any object
• This means that a Class’s
– static methods can be called even if no objects of that
class have been created and
– static data is “shared” by all instances (i.e., one rvalue
per class instead of one per instance
class StaticTest {static int i = 47;}
StaticTest st1 = new StaticTest();
StaticTest st2 = new StaticTest();
// st1.i == st2.I == 47
StaticTest.i++; // or st1.I++ or st2.I++
// st1.i == st2.I == 48
9. UMBC CMSC 331 Java 9
Array Operations
• Subscripts always start at 0 as in C
• Subscript checking is done automatically
• Certain operations are defined on arrays of objects,
as for other classes
– e.g. myArray.length == 5
11. Echo.java
C:UMBC331java>type echo.java
// This is the Echo example from the Sun tutorial
class echo {
public static void main(String args[]) {
for (int i=0; i < args.length; i++) {
System.out.println( args[i] );
}
}
}
C:UMBC331java>javac echo.java
C:UMBC331java>java echo this is pretty silly
this
is
pretty
silly
C:UMBC331java>
12. UMBC CMSC 331 Java 12
Factorial Example
/**
* This program computes the factorial of a number
*/
public class Factorial { // Define a class
public static void main(String[] args) { // The program starts here
int input = Integer.parseInt(args[0]); // Get the user's input
double result = factorial(input); // Compute the factorial
System.out.println(result); // Print out the result
} // The main() method ends here
public static double factorial(int x) { // This method computes x!
if (x < 0) // Check for bad input
return 0.0; // if bad, return 0
double fact = 1.0; // Begin with an initial value
while(x > 1) { // Loop until x equals 1
fact = fact * x; // multiply by x each time
x = x - 1; // and then decrement x
} // Jump back to the star of loop
return fact; // Return the result
} // factorial() ends here
} // The class ends here
From Java in a Nutshell
13. UMBC CMSC 331 Java 13
JAVA Classes
• The class is the fundamental concept in JAVA (and other
OOPLs)
• A class describes some data object(s), and the operations
(or methods) that can be applied to those objects
• Every object and method in Java belongs to a class
• Classes have data (fields) and code (methods) and classes
(member classes or inner classes)
• Static methods and fields belong to the class itself
• Others belong to instances
14. UMBC CMSC 331 Java 14
Example
public class Circle {
// A class field
public static final double PI= 3.14159; // A useful constant
// A class method: just compute a value based on the arguments
public static double radiansToDegrees(double rads) {
return rads * 180 / PI;
}
// An instance field
public double r; // The radius of the circle
// Two methods which operate on the instance fields of an object
public double area() { // Compute the area of the
circle
return PI * r * r;
}
public double circumference() { // Compute the circumference of
the circle
return 2 * PI * r;
}
}
15. UMBC CMSC 331 Java 15
Constructors
• Classes should define one or more methods to create or
construct instances of the class
• Their name is the same as the class name
– note deviation from convention that methods begin with lower case
• Constructors are differentiated by the number and types of
their arguments
– An example of overloading
• If you don’t define a constructor, a default one will be
created.
• Constructors automatically invoke the zero argument
constructor of their superclass when they begin (note that
this yields a recursive process!)
16. UMBC CMSC 331 Java 16
Constructor example
public class Circle {
public static final double PI = 3.14159; // A constant
public double r; // instance field holds circle’s radius
// The constructor method: initialize the radius field
public Circle(double r) { this.r = r; }
// Constructor to use if no arguments
public Circle() { r = 1.0; }
// better: public Circle() { this(1.0); }
// The instance methods: compute values based on radius
public double circumference() { return 2 * PI * r; }
public double area() { return PI * r*r; }
}
this.r refers to the r
field of the class
This() refers to a
constructor for the class
17. UMBC CMSC 331 Java 17
Extending a class
• Class hierarchies reflect subclass-superclass relations among
classes.
• One arranges classes in hierarchies:
– A class inherits instance variables and instance methods from all of its
superclasses. Tree -> BinaryTree -> BST
– You can specify only ONE superclass for any class.
• When a subclass-superclass chain contains multiple instance
methods with the same signature (name, arity, and argument
types), the one closest to the target instance in the subclass-
superclass chain is the one executed.
– All others are shadowed/overridden.
• Something like multiple inheritance can be done via interfaces
(more on this later)
• What’s the superclass of a class defined without an extends
clause?
18. UMBC CMSC 331 Java 18
Extending a class
public class PlaneCircle extends Circle {
// We automatically inherit the fields and methods of Circle,
// so we only have to put the new stuff here.
// New instance fields that store the center point of the circle
public double cx, cy;
// A new constructor method to initialize the new fields
// It uses a special syntax to invoke the Circle() constructor
public PlaneCircle(double r, double x, double y) {
super(r); // Invoke the constructor of the superclass, Circle()
this.cx = x; // Initialize the instance field cx
this.cy = y; // Initialize the instance field cy
}
// The area() and circumference() methods are inherited from Circle
// A new instance method that checks whether a point is inside the circle
// Note that it uses the inherited instance field r
public boolean isInside(double x, double y) {
double dx = x - cx, dy = y - cy; // Distance from center
double distance = Math.sqrt(dx*dx + dy*dy); // Pythagorean theorem
return (distance < r); // Returns true or false
}
}
19. UMBC CMSC 331 Java 19
Overloading, overwriting, and shadowing
• Overloading occurs when Java can distinguish two procedures with the
same name by examining the number or types of their parameters.
• Shadowing or overriding occurs when two procedures with the same
signature (name, the same number of parameters, and the same
parameter types) are defined in different classes, one of which is a
superclass of the other.
20. UMBC CMSC 331 Java 20
On designing class hierarchies
• Programs should obey the explicit-representation principle, with classes
included to reflect natural categories.
• Programs should obey the no-duplication principle, with instance methods
situated among class definitions to facilitate sharing.
• Programs should obey the look-it-up principle, with class definitions
including instance variables for stable, frequently requested information.
• Programs should obey the need-to-know principle, with public interfaces
designed to restrict instance-variable and instance-method access, thus
facilitating the improvement and maintenance of nonpublic program
elements.
• If you find yourself using the phrase an X is a Y when describing the
relation between two classes, then the X class is a subclass of the Y class.
• If you find yourself using X has a Y when describing the relation between
two classes, then instances of the Y class appear as parts of instances of the
X class.
21. UMBC CMSC 331 Java 21
Data hiding and encapsulation
• Data-hiding or encapsulation is an important part
of the OO paradigm.
• Classes should carefully control access to their data
and methods in order to
– Hide the irrelevant implementation-level details so they
can be easily changed
– Protect the class against accidental or malicious damage.
– Keep the externally visible class simple and easy to
document
• Java has a simple access control mechanism to help
with encapsulation
– Modifiers: public, protected, private, and package
(default)
22. UMBC CMSC 331 Java 22
Example
encapsulation
package shapes; // Specify a package for the class
public class Circle { // The class is still public
public static final double PI = 3.14159;
protected double r; // Radius is hidden, but visible to subclasses
// A method to enforce the restriction on the radius
// This is an implementation detail that may be of interest to subclasses
protected checkRadius(double radius) {
if (radius < 0.0)
throw new IllegalArgumentException("radius may not be negative.");
}
// The constructor method
public Circle(double r) {checkRadius(r); this.r = r; }
// Public data accessor methods
public double getRadius() { return r; };
public void setRadius(double r) { checkRadius(r); this.r = r;}
// Methods to operate on the instance field
public double area() { return PI * r * r; }
public double circumference() { return 2 * PI * r; }
}
23. UMBC CMSC 331 Java 23
Access control
• Access to packages
– Java offers no control mechanisms for packages.
– If you can find and read the package you can access it
• Access to classes
– All top level classes in package P are accessible
anywhere in P
– All public top-level classes in P are accessible anywhere
• Access to class members (in class C in package P)
– Public: accessible anywhere C is accessible
– Protected: accessible in P and to any of C’s subclasses
– Private: only accessible within class C
– Package: only accessible in P (the default)
25. UMBC CMSC 331 Java 25
Getters and setters
• A getter is a method that extracts information from an instance.
– One benefit: you can include additional computation in a getter.
• A setter is a method that inserts information into an instance (also
known as mutators).
– A setter method can check the validity of the new value (e.g., between 1
and 7) or trigger a side effect (e.g., update a display)
• Getters and setters can be used even without underlying matching
variables
• Considered good OO practice
• Essential to javabeans
• Convention: for variable fooBar of type fbtype, define
– getFooBar()
– setFooBar(fbtype x)
26. UMBC CMSC 331 Java 26
Example
getters and setters
package shapes; // Specify a package for the class
public class Circle { // The class is still public
// This is a generally useful constant, so we keep it public
public static final double PI = 3.14159;
protected double r; // Radius is hidden, but visible to subclasses
// A method to enforce the restriction on the radius
// This is an implementation detail that may be of interest to subclasses
protected checkRadius(double radius) {
if (radius < 0.0)
throw new IllegalArgumentException("radius may not be negative.");
}
// The constructor method
public Circle(double r) { checkRadius(r); this.r = r;}
// Public data accessor methods
public double getRadius() { return r; };
public void setRadius(double r) { checkRadius(r); this.r = r;}
// Methods to operate on the instance field
public double area() { return PI * r * r; }
public double circumference() { return 2 * PI * r; }
}
27. UMBC CMSC 331 Java 27
Abstract classes and methods
• Abstract vs. concrete classes
• Abstract classes can not be instantiated
public abstract class shape { }
• An abstract method is a method w/o a body
public abstract double area();
• (Only) Abstract classes can have abstract methods
• In fact, any class with an abstract method is
automatically an abstract class
28. UMBC CMSC 331 Java 28
Example
abstract class
public abstract class Shape {
public abstract double area(); // Abstract methods: note
public abstract double circumference();// semicolon instead of body.
}
class Circle extends Shape {
public static final double PI = 3.14159265358979323846;
protected double r; // Instance data
public Circle(double r) { this.r = r; } // Constructor
public double getRadius() { return r; } // Accessor
public double area() { return PI*r*r; } // Implementations of
public double circumference() { return 2*PI*r; } // abstract methods.
}
class Rectangle extends Shape {
protected double w, h; // Instance data
public Rectangle(double w, double h) { // Constructor
this.w = w; this.h = h;
}
public double getWidth() { return w; } // Accessor method
public double getHeight() { return h; } // Another accessor
public double area() { return w*h; } // Implementations of
public double circumference() { return 2*(w + h); } // abstract methods.
}
29. UMBC CMSC 331 Java 29
Syntax Notes
• No global variables
– class variables and methods may be applied to any
instance of an object
– methods may have local (private?) variables
• No pointers
– but complex data objects are “referenced”
• Other parts of Java are borrowed from PL/I,
Modula, and other languages