Module-1.pdf

INTRODUCTION 210301301 CORE JAVA 210301305 PRACTICAL ON CORE JAVA BY: Prof. Nirav Suthar INTRODUCTION TO CORE JAVA 1 210301301 CORE JAVA UNIT MODULES WEIGHTAGE 1 In...

INTRODUCTION 210301301 CORE JAVA 210301305 PRACTICAL ON CORE JAVA BY: Prof. Nirav Suthar INTRODUCTION TO CORE JAVA 1 210301301 CORE JAVA UNIT MODULES WEIGHTAGE 1 Introduction to Java 20 % 2 Java Programming Constructs, Classes, Vectors 20 % and Arrays 3 Inheritance, Interface and Packages 20 % 4 Exception Handling and Multi - Threading 20 % 5 Applets 20 % INTRODUCTION TO CORE JAVA 2  Unit – I Introduction to Java  Object Oriented Concepts  Introduction  Need of OOP  Principles of OOP  Java v/s Procedural Language v/s OOP  History of Java  Java Essentials  Java Features  Java Program Structure  Java Architecture  Introduction to Java framework  Real Time Java Applications INTRODUCTION What is Java? Java is a popular programming language, created in 1995. It is owned by Oracle, and more than 3 billion devices run Java. It is used for: Mobile applications (specially Android apps) Artificial Intelligence Big Data Serverless Architecture Spring Framework Cloud based Models Remote Access Solutions Need of OOP Disadvantages of OOP : Data is exposed to whole program, so no security for data. Difficult to relate with real world objects. Importance is given to the operation on data rather than the data. Difficult to create new data types reduces extensibility. Examples of Procedural languages : BASIC C Pascal FORTRAN Need of OOP Advantages of OOP : OOP provides a clear modular structure for programs. It is good for defining abstract data types. Implementation details are hidden from other modules and other modules has a clearly defined interface. It is easy to maintain and modify existing code as new objects can be created with small differences to existing ones. Objects, methods, instance, message passing, inheritance are some important properties provided by these particular languages. Ecapsulation, polymorphism, abstraction are also counts in these fundamentals of programming language. It implements real life scenario. Introduction to OOP Object + Oriented + Programming Deals with object to build program & software Object = Identity + Attributes + Behaviour Principles of OOP Class Object Data Abstraction Data Encapsulation Polymorphism Inheritance Principles of OOP Language Classes: Collection of similar objects Objects: Instance of class Abstraction: Hiding the implementation details and showing only functionality to the user. Inheritance: Adopt the characteristics of one class into another class Encapsulation: Wrapping of data in single unit Polymorphism:Perform a single action by different ways What is JAVA ? Java is a popular programming language, created in 1995. It is owned by Oracle, and more than 3 billion devices run Java. Java is a high level, robust, secured and object-oriented programming language. “Java is a programming language and a platform.” Java Applications are called WORA (Write Once Run Anywhere) Platform: Any hardware or software environment in which a program runs, is known as a platform. Since Java has its own runtime environment (JRE) and API, it is called platform. Common devices that run Java Airplane Systems Lottery Systems ATMs MRIs BlackBerry Smartphones On-Board Computer Systems Blu-ray Disc Players Parking Meters Cable Boxes PlayStation Consoles Cell Phones Printers Computers Public Transportation Passes Credit Cards Robots CT Scanners Routers Government IDs Smart Grid Meters Home Security Systems TVs Kindle E-Readers Vehicle Diagnostic Systems Livescribe Smartpens VoIP Phones History of Java James Gosling, Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. The small team of sun engineers called Green Team. Originally designed for small, embedded systems in electronic appliances like set-top boxes. Firstly, it was called "Greentalk" by James Gosling and file extension was.gt. After that, it was called Oak and was developed as a part of the Green project. History of Java Why Sun choosed "Oak" name? Why Oak? Oak is a symbol of strength and choosen as a national tree of many countries like U.S.A., France, Germany, Romania etc. In 1995, Oak was renamed as "Java" because it was already a trademark by Oak Technologies. History of Java Why sun choosed "Java" name? The team gathered to choose a new name. The suggested words were "dynamic", "revolutionary", "Silk", "jolt", "DNA" etc. They wanted something that reflected the essence of the technology: revolutionary, dynamic, lively, cool, unique, and easy to spell and fun to say. According to James Gosling "Java was one of the top choices along with Silk". Since java was so unique, most of the team members preferred java. Java is an island of Indonesia where first coffee was produced (called java coffee). JDK 1.0 released in(January 23, 1996). History of Java Java SE 17 (September 2021) Java SE 18 (to be released by March 2022) C v/s C++ v/s JAVA Metrics C C++ Java Programming Procedural Object-Oriented Pure Object Paradigm language Programming (OOP) Oriented Oriented Origin Based on Based on C language Based on C and C++ Assembly language Developer Dennis Ritchie in Bjarne Stroustrup in James Gosling in 1972 1979 1991 Translator Compiler only Compiler only Interpreted language (Compiler + interpreter) Platform Platform Platform Dependent Platform Dependency Dependent Independent Code execution Direct Direct Executed by JVM (Java Virtual Machine) Approach Top-down Bottom-up approach Bottom-up approach approach C v/s C++ v/s JAVA Metrics C C++ Java File generation.exe files.exe files.class files Pre-processor Support header Supported (#header, Use Packages directives files (#include, #define) (import) #define) keywords Support 32 Supports 63 keywords 50 defined keywords keywords Datatypes Supported Supported Not supported (union, structure) Inheritance No inheritance Supported Supported except Multiple inheritance Overloading No overloading Support Function Operator overloading overloading is not supported (Polymorphism) Pointers Supported Supported Not supported C v/s C++ v/s JAVA Metrics C C++ Java Allocation Use malloc, calloc Use new, delete Garbage collector Exception Not supported Supported Supported Handling Templates Not supported Supported Not supported Destructors No constructor Supported Not supported neither destructor Multithreading/ Not supported Not supported Supported Interfaces Database Not supported Not supported Supported connectivity Storage Classes Supported Supported Not supported ( auto, extern ) ( auto, extern )  Java Features Object Oriented − In Java, everything is an Object. Java can be easily extended since it is based on the Object model. Platform Independent − Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by the Virtual Machine (JVM) on whichever platform it is being run on. Simple − Java is designed to be easy to learn. If you understand the basic concept of OOP Java, it would be easy to master. Secure − With Java's secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption. Java Features Portable − Being architecture-neutral and having no implementation dependent aspects of the specification makes Java portable. Robust − Java makes an effort to eliminate error prone situations by emphasizing mainly on compile time error checking and runtime checking. Multithreaded − With Java's multithreaded feature it is possible to write programs that can perform many tasks simultaneously. This design feature allows the developers to construct interactive applications that can run smoothly. Architecture-neutral - Java is architecture neutral because there are no implementation dependent features, for example, the size of primitive types is fixed. Java Features Interpreted − Java byte code is translated on the fly to native machine instructions and is not stored anywhere. The development process is more rapid and analytical since the linking is an incremental and light-weight process. High Performance − With the use of Just-In-Time compilers, Java enables high performance. Distributed − Java is designed for the distributed environment of the internet. Dynamic − Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry extensive amount of run-time information that can be used to verify and resolve accesses to objects on run-time. Java Version JDK Alpha and Beta (1995) JDK 1.0 (23rd Jan 1996) JDK 1.1 (19th Feb 1997) J2SE 1.2 (8th Dec 1998) J2SE 1.3 (8th May 2000) J2SE 1.4 (6th Feb 2002) J2SE 5.0 (30th Sep 2004) Java SE 6 (11th Dec 2006) Java SE 7 (28th July 2011) Java SE 8 (18th Mar 2014) Java SE 9 (21st Sep 2017) Java SE 10 (20th Mar 2018) Java SE 11 (September 2018) Java SE 12 (March 2019) Java SE 13 (September 2019) Java SE 14 (Mar 2020) Java SE 15 (September 2020) Java SE 16 (Mar 2021) Java SE 17 (September 2021) Java SE 18 (to be released by March 2022) Why use Java? Java works on different platforms (Windows, Mac, Linux, Raspberry Pi, etc.) It is one of the most popular programming language in the world It is easy to learn and simple to use It is open-source and free It is secure, fast and powerful It has a huge community support (tens of millions of developers) Java is an object oriented language which gives a clear structure to programs and allows code to be reused, lowering development costs As Java is close to C++ and C#, it makes it easy for programmers to switch to Java or vice versa. Common Terminologies used in Java Java Virtual Machine (JVM) Bytecode Java Development Kit (JDK) Java Runtime Environment (JRE) Garbage Collector ClassPath Java Virtual Machine(JVM): This is generally referred to as JVM. There are three execution phases of a program. They are writting a program, compiling it and running the program. Writing a program is done by a java programmer. The compilation is done by the JAVAC compiler which is a primary Java compiler included in the Java development kit (JDK). It takes Java program as input and generates bytecode as output. In the Running phase of a program, JVM executes the bytecode generated by the compiler. The function of Java Virtual Machine is to execute the bytecode produced by the compiler. Every Operating System has a different JVM but the output they produce after the execution of bytecode is the same across all the operating systems. Thus Java is known as a platform-independent language. Bytecode Bytecode is generated in the Development process: The Javac compiler of JDK compiles the java source code into bytecode so that it can be executed by JVM. It is saved as.class file by the compiler. To view the bytecode, a disassembler like javap can be used. The javap tool is used to get the information of any class or interface. The javap command (also known as the Java Disassembler) disassembles one or more class files. Java Runtime Environment (JRE): JDK includes JRE. JRE installation on our computers allows the java program to run, however, we cannot compile it. JRE includes a browser, JVM, applet supports, and plugins. For running the java program, a computer needs JRE. Java Development Kit(JDK): It is a complete Java development kit that includes everything including compiler, Java Runtime Environment (JRE), java debuggers, java docs, etc. For the program to execute in java, we need to install JDK on our computer in order to create, compile and run the java program. The JDK is a development environment for building applications, applets, and components using the Java programming language. The JDK includes tools useful for developing and testing programs written in the Java programming language and running on the Java platform. How to install JDK? https://www.oracle.com/java/technologies/downloads/ –Use the above link to download and install Garbage Collector: In Java, programmers can’t delete the objects. To delete or recollect that memory JVM has a program called Garbage Collector. Garbage Collectors can recollect the of objects that are not referenced. ClassPath: The classpath is the file path where the java runtime and Java compiler look for.class files to load. By default, JDK provides many libraries. If you want to include external libraries they should be added to the classpath. Java Architecture Java Architecture In Java, there is a process of compilation and interpretation. The code written in Java, is converted into byte codes which is done by the Java Compiler. The Just-In-Time (JIT) compiler is a an essential part of the JRE i.e. Java Runtime Environment, that is responsible for performance optimization of java based applications at run time. The byte codes, then are converted into machine code by the JVM. The Machine code is executed directly by the machine. Java Architecture Java Virtual Machine (JVM) is a engine that provides runtime environment to drive the Java Code or applications. It converts Java bytecode into machines language. JVM is a part of Java Run Environment (JRE). JVM is responsible for allocating memory space. Java Architecture There are three main components of Java language: –JVM, JRE, and JDK. Java Virtual Machine, Java Runtime Environment and Java Development Kit respectively. Java Programming Structure class Simple { public static void main(String args[]) { System.out.println("Hello Java"); } } To compile: javac Simple.java To execute: java Simple Java Programming Structure class keyword is used to declare a class in java. public keyword is an access modifier which represents visibility, it means it is visible to all. static is a keyword, if we declare any method as static, it is known as static method. The core advantage of static method is that there is no need to create object to invoke the static method. The main method is executed by the JVM, so it doesn't require to create object to invoke the main method. So it saves memory. void is the return type of the method, it means it doesn't return any value. main represents startup of the program. String[] args is used for command line argument. System.out.println() is used print statement. Introduction to Java framework Frameworks are large bodies of pre-written code to which you add your own code in order to solve a problem. You make use of a framework by calling its methods, inheritance, and supplying callbacks, listeners, or other implementations of the patterns. A framework will often dictate the structure of an application. Some frameworks even supply so much code that you have to do very little to write your application. Top Java Frameworks used Spring Hibernate JavaServer Faces [JSF] Struts Google web toolkit [GWT] Grails Vaadin Blade Dropwizard Play Real Time Java Applications 1) Android Apps 2) Server Apps at Financial Services Industry 3) Java Web applications 4) Software Tools 5) Trading Application 6) J2ME Apps 7) Embedded Space 8) Big Data technologies 9) High Frequency Trading Space 10) Scientific Applications Variables “ Variable is a name of memory location “ int data=123; Variable is a symbolic name refer to a memory location used to store values that can change during the execution of a program. Example: int a = 10; Here, int = data type a = identifier 10 = literal There are three types of variables in java: local, instance and static. Variables 1) Local Variable A variable which is declared inside the method is called local variable. 2) Instance Variable A variable which is declared inside the class but outside the method, is calle 3) Static variable A variable that is declared as static is called static variable. It cannot be loca Variables class A { int data=50;//instance variable static int m=100;//static variable void method() { int n=90;//local variable } } MarksDemo.java Student1.java Data Types There are two types of data types in java: –primitive –non-primitive Primitive data types are the basic blocks of any programming language. It can have only one value at a time. Data Types Data Types Non primitive data types are also referred to as derived types. Java supports non primitive data types like classes, interfaces, and arrays. Identifiers Are names assigned to variables, methods,constant,classes,packages and interfaces. No limit has been specified for length. Rules: 1. first letter must be a letter,underscore,dollar sign 2. subsequent can be letter,underscore,dollar,digit 3. white space is not allowed 4. identifiers are case sensitive 5. don't use keywords. Identifiers Class or Interface Identifiers Variable or Method Identifiers Constant Identifiers Package Identifiers Naming Convention Class or Interface Identifiers –Must begin with a capital letter. –First alphabet of internal word should also be capitalized. –Example: public class MyClass public class Employee Variable or Method Identifiers –Must begin with a small case letter. –First alphabet of internal word should also be capitalized. –Example: int myNumber Naming Convention Constant Identifiers –Must be specified in upper case. –_ is used to separate internal words. –Example: final double RATE = 2.6 Package Identifiers –Must be specified in small case letters. –Example: Package mypackage.subpackage.x; Keywords Are predefined identifiers meant for specific purpose. Reserve words All keywords are in lower case. Ex: case,catch,if,float,int,package,while,do,long Literals Is a value that can be passed to a variable or constant in a program. Numeric : binary,octal(0-7,017),hexa Boolean: 0’s and 1’s Character : enclosed with quotes String : zero or more characters Null : assigned to object reference variable Operators Using one or more operands Unary operator(+) Binary operator(/) Ternary operator(?:) Assignment/Arithmetic operator Sets the value of a variable to some new value. Right to left associativity a=b=0 Ex: +=,-=,|= a+=b Relational operator Java return either true or false Equal to == Not equal to != Less than < Greater than > Less than or equal to = Boolean logical operators Conditional OR || Conditional AND && Logical OR |(TRUE: one is true) Logical AND &(FALSE: one is false) Logical XOR ^(FALSE: T & T) Unary logical NOT ! Ex: bolean a=true; bolean b=false; Expression An expression is a construct made up of variables, operators, and method invocations, which are constructed according to the syntax of the language, that evaluates to a single value. Int ans= 1 + 10; Precedence Rule & Associativity Primitive type conversion & casting Assigning a value of one type to a variable of another type is known as Type Casting. Convert.java Widening or Automatic type converion Automatic Type casting take place when, the two types are compatible the target type is larger than the source type Narrowing or Explicit type conversion When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting. Data Input There are 2 ways to take input in Java –JOptionPane class –Scanner class Scanner Class Terminal The java.util.Scanner class is a simple text scanner which can parse primitive types and strings using regular expressions. This Scanner class is found in java.util package. Following are the important points about Scanner: –The Java Scanner class breaks the input into tokens using a delimiter that is white space. –Java Scanner class is widely used to parse text for string and primitive types using regular expression. –A Scanner is not safe for multithreaded use without external synchronization. Scanner Class Terminal It is the simplest way to get input in Java. By the help of Scanner in Java, we can get input from the user in primitive types such as int, long, double, byte, float, short, etc. Scanner Class Terminal How to take Input int n; n = s.nextInt(); // s is object of Scanner class Statement n = s.nextInt(); is used to input the value of an integer variable 'n' from the user. Here, nextInt() is a method of the object s of the Scanner class. Scanner Class Terminal Method Inputs nextInt() Integer nextFloat() Float nextDouble() Double nextLong() Long nextShort() Short next() Single word nextLine() Line of Strings nextBoolean() Boolean The only difference between the methods nextLine() and next() is that nextLine() reads the entire line including white spaces, whereas next() reads only upto the first white space and then stops. Scanner Class Terminal Conditional Statements Java has the following conditional statements: if if-else nested-if if-else-if switch-case Loops Java has following looping constructs: while do-while for for-each For-each loop It starts with the keyword for like a normal for-loop. Instead of declaring and initializing a loop counter variable, you declare a variable that is the same type as the base type of the array, followed by a colon, which is then followed by the array name. In the loop body, you can use the loop variable you created rather than using an indexed array element. It’s commonly used to iterate over an array or a Collections class (eg, ArrayList) It makes the code more readable. It eliminates the possibility of programming errors. For-each loop Syntax: for (type var : array) { statements using var; } is equivalent to: for (int i=0; i0; i--) { System.out.println(numbers[i]);} For-each cannot process two decision making statements at once // cannot be easily converted to a for-each loop for (int i=0; i