Corejava Training in Bangalore Tutorial

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CORE JAVA

Core Java Syllabus
A First Look
A Simple Java Class
Java’s “Hello World” Program
Java Basics
Language and Platform Features
Program Life Cycle
The Java SE Development Kit (JDK)

Class and Object Basics
The Object Model and Object-Oriented Programming
Classes, References, and Instantiation
Adding Data to a Class Definition
Adding Methods (Behavior)
More on Classes and Objects
Accessing data, the “this” variable
Encapsulation and Access Control, public and private
Access
Constructors and Initialization
static Members of a Class
Scopes, Blocks, References to Objects

Flow of Control[briefly due to attendee
experience]
Branching: if, if-else, switch
Iteration: while, do-while, for, break, continue
Strings and Arrays
String, StringBuffer, StringBuilder
Arrays, Primitive Arrays, Arrays of Reference Types
varargs

Packages
Package Overview – Using Packages to Organize Code
import statements
Creating Packages, package Statement, Required
Directory Structure
Finding Classes, Packages and Classpath
Composition and Inheritance
Using Composition to Deal With Complexity
Composition/HAS-A, Delegation
Using Inheritance and Polymorphism to share commonality
IS-A, extends, Inheriting Features, Overriding Methods,
Using Polymorphism
Class Object
Abstract Classes

Advanced Stream Techniques
Buffering
Data Streams
Push-Back Parsing
Byte-Array Streams and String Readers and Writers
Java Serialization
The Challenge of Object Serialization
Serialization API, Serializable Interface
ObjectInputStream and ObjectOutputStream
The Serialization Engine
Transient Fields
readObject and writeObject
Externalizable Interface

Interfaces
Using Interfaces to Define Types
Interfaces and Abstract Classes
Exceptions
Exceptions and the Exception Hierarchy
try and catch
Handling Exceptions
Program Flow with Exceptions
Finally

Java Collections and Generics
The Collections Framework and its API
Collections and Java Generics
Collection, Set, List, Map, Iterator
Autoboxing
Collections of Object (non-generic)
Using ArrayList, HashSet, and HashMap
for-each Loop
Processing Items With an Iterator
More About Generics

The Java Streams Model
Delegation-Based Stream Model
InputStream and OutputStream
Media-Based Streams
Filtering Streams
Readers and Writers
Working with Files
File Class
Modeling Files and Directories
File Streams
Random-Access Files

Comments are almost like C++
• The javadoc program generates HTML API
documentation from the “javadoc” style comments in
your code.
/* This kind comment can span multiple lines */
// This kind is of to the end of the line
/* This kind of comment is a special
* ‘javadoc’ style comment
*/

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
•
•
•
•
•

An example of a class
class Person {
String name;
int age;
Variable
Method
void birthday ( )
{
age++;
System.out.println (name + '
is now ' + age);
}
}

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.

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 */

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++; st2.I+
+
// st1.i == st2.I == 48
// or st1.I++ or

Example
public class Circle {
// A class field
public static final double
PI= 3.14159; constant
// A class method: just
compute a value
// A useful
based on thearguments
public static double
radiansToDegrees(double rads) { return rads *
180 / PI;
}// An instance field
public double r;
circle
// Two methodswhich
an object
// The radius of the
operate on
{
the instance
// Compute
fields of
the area of
public double
the circle
return PI *
area()
r * r;}
public
double
circumference() { // Compute the
circumference of the circle
return 2 * PI * r;
}
}

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

An array is an object
NSIT ,Jetalpur
• Person mary = new Person ( );
• int
• int
myArray[
myArray[
] = new
] = {1, 4, 9,
16,
int[5];
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!

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

Factorial Example
/* This program computes the factorial of a number
*/
public class Factorial {
public static void
main(String[] args) { here
int input =
Integer.parseInt(args[0]); input
double result =
factorial(input); factorial
System.out.println(result); result
}
ends here
// Define a class
// The program
starts
// Get the user's
// Compute the
// Print out the
// The main() method
public static double
computes x!
if (x <
0) return 0.0;
double fact =
1.0; initial value
factorial(int x) { // This method
// Check for bad input
// if bad,
return 0
// Begin with an
while(x > 1)
{ fact = fact *
x;
each time
// Loop until
// multiply
x equals
by x
// and then

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!)

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() {}

Corejava Training in Bangalore Tutorial

Corejava Training in Bangalore Tutorial

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Corejava Training in Bangalore Tutorial