java

1. N ART ADAR SARASAWATHI COLLEGE OF
ART &SCIENCE,Theni

2. METHODS AND CLASSES
 It examies several topics relating to
methods,including overloading,parameter,passing and
recrsion.
 The class , discussing access control , the use of the
keyword staic , and or of java’s most important
built-in classes string.

3. Overloading methods
 When this is the case the methods are said to be
overloading and the process is referred to as method
overloading.
 Thus overloaded methods must may have different
return/or number of their parameters.
 two versions of a method :
Overloaded method
Simply executes method

4.  As you can see test() is overloaded four times.
 at no parameters,
 The first version takes no parameters,
 The second takes integer parameter,s
 Third tat the takes two integer parameters,
 Fourth takes one double parameter.
 The fact that the fourth of test() also return a value is
of no consequence relative to overloaded.
 Since return types do not play a role in overload
resolution.

5. Using objects as parameters
 As you can , see the equal() method inside Test
compares two objects for equality and return the
result.
 If they contain the same values, that then the method
return true.
 Otherwise it return false. Notice that the parameter o
in equals() Test as its type.
 Version of Box allows one object to initialize.

6. A closer look at argument passing
 There are two way is that a language.
 The first way is call-by-value.
 Value of argument into the formal parameter of the
subroutine.
 The second way an argument can be passed is call-
by-reference.
 Not value of the argument.
 Operation that occur inside meth() have no effect on
the values of a and b used in the call;

7. Returning objects
 A method can return any type of data including class
type that you create.
 incrByTen() meyhod.
 As you each time incrByTen() is invoked new object is
created and a reference to is returned to the calling
routine.
 The all object are dynamically allocated using new, you
don’t need to worry about an object going out-of-
scope.

8. recursion
 Java support recursion.
 A method that calls itself is said to be recursive.
 The classic example recursion product of all the whole
numbers between 1 and N of the factorial of number.
 for example 3 factorial 1*2*3, or 6.
 Use println() statements liberally during development
.

9. Introducing Access Control
 As you know encapsulation link data with the code that
manipulates.
 Encapsulation provide another another important
attritube: access control.
 Correctly implemented a class create a “black box inner
working not open to tempering.
 For example consider the stack class end of true the
methods push() and pop()provide a controlled interface to
the stack not enforced.
 Java’s access speccifiers are
public,private,protected.
 Protected applies only when inheritance.

10.  Let’s begin by defining public and private. when a
member of a class is modified a the public specified
then the member can be accessed by any other code.
 Public methods:
 setc() and get().
 Remove the comment symbol from the beginning of
the.
 ob.c=100;

11. Understanding static
 There will be times when you will want to define a class
member that will be used independently of any object of
that class.
 When a member is decleared static it can be accessed
before any objects of class are created.
 Example : static main() decleared as static called before
any objects exist.
 Methods declared as static methods:
 They can only call other static methods.
 They must only access static data.
 They cannot refer to this or super in any way.

12.  static method from outside its class,
classname.method()
• Inside main(),the static method callme() and
static variable b are accessed through class name
staticDemo.

13. Introducing final
 A variable can be declared as final.
 Subsequent parts of your program can now use
FILE_OPEN,etc., as if they were constants,without
fear that a value has been changed.
 Thus final variable is essentially a constant.
 This second usage of final is described in the next
inheritance is described.

14. Array revisited
 Now that you know about classes, an important point
can about about arrays:
 The size of an array-that is the number of element that
an array can hold-is found in its length instance
variable.
 Program create two stacks:
 one five elements other eight element deep.
 array maintain their own length own information
makes easy create stacks of any size.

15.  Inner class named Inner within scope of class Outer.
 Inner can directly access the variable outer_x.
 The main() method of InnerClassDemo creates
an instance of class outer and invokes its test()
method.
 Instance variable of showy().

16. Introducing nested and inner meth
classes
 Such classes are known as nested classes.
 There are two type of nested classess:
 static and non-static.
 The most important type of static nested classes inner
class.
 The class named outer has one instance variable
named outer_x, one instance method named test()
and defines inner called inner.
 Inner class named Inner is defined scope class Outer.

17. Exploring the string class
 String is probably the most commonly used in java’s
class library.
• Even string constants are actually string objects.
• If you need to change a string can always create a new
one that contains the modifications.
• Java defines a peer class String called StringBufffer,
• “I like Java”.

18. Using command-line arguments
 This is accompolihed passing command-line
arguments to main().
 A command –line argument is the information that
directly follow the program’s name on the command
line when is executed.
 The first command line argument is stored at args[0]
 The second a args[1]