Project Report Java Programming

Information Technology

Topic

Wrapper Class and

Nesting of Methods

Submitted By

Deepika Mittal

BCA IInd Year

Dezyne E’cole College

www.dezyneecole.com

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Project Report

On

Java Programming

At

Dezyne E’cole College

Ajmer

Submitted to

Dezyne E’cole College

Towards The

Partial Fulfillment on

Bachelor’s of Computer Application

By

Deepika Mittal

Dezyne E’cole College

106/10, Civil line, Ajmer

Tel:–0145-2624679

www.dezyneecole.com

2016-17

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ACKNOWLEDGMENT

I Deepika Mittal, Student of Dezyne E’cole College, an Externally Grateful

To Each and Every Individual Who Has Contributed In Successful

Completion of My Project. I Express My Gratitude Towards Dezyne E’cole

College For Their Guidance And Constant Supervision As Well As For

Providing The Necessary Information And Support Regarding The

Completion of Project.

Thank You

SYNOPSIS

This Project is a Miner Project Mode, Based on the Theoretical Concepts

of Java. This Project Has Made our Basic Concepts on Java Strong.

Q. What is wrapper class and Methods of Nesting?

Ans.

Wrapper Classes

As pointed out earlier. Vector cannot handle primitive data types like int, float, char, and double.

Primitive data type may be converted into object types by using the wrapper classes contained

in the java.lang Package. Following table shows the simple data types and their corresponding

wrapper class types.

Wrapper Classes For Converting Types:-

Simple Type Wrapper Class Boolean Boolean

Char Character

Double Double

Float Float

Int Integer

Long Long

The wrapper classes have a number of unique methods for handling primitive data type and

objects. They are listed in the following tables.

Converting Primitive Numbers to Object Number Using Constructor

Method:-

Constructor Calling Conversion Action Integer IntVal=new Integer(i); Primitive integer to Integer Object

Float FloatVal=new Float(f); Primitive float to Float Object

Double DoubleVal=new Double(d); Primitive double to Double Object

Long LongVal=new Long(l); Primitive long to Long Object

Converting Object Numbers to Primitive Number Using typeValue()

Method:-

Method Calling Conversion Action int i=IntVal.intValue(); Object to Primitive integer

float f=FloatVal.floatValue(); Object to Primitive float

long l=LongVal.longValue(); Object to Primitive long

double d=DoubleVal.doubleValue(); Object to Primitive double

Converting Numbers to String Using to String () Method:-

Method Calling Conversion Action str= Integer.toString(i); Primitive integer to string

str= Float.toString(f); Primitive float to string

str= Double.toString(d); Primitive double to string

str= Long.toString(l); Primitive long to string

Converting String Objects to Numbers Objects Using the Static Method

valueOf ():-

Method Calling Conversion Action DoubleVal = Double.ValueOf(str); Converts string to Double object

FloatVal = Float.ValueOf(str); Converts string to Float object

IntegerVal = Integer.ValueOf(str); Converts string to Integer object

LongVal = Long.ValueOf(str); Converts string to Long object

Converting Numeric String to Primitive Numbers Using Parsing Methods:-

Method Calling Conversion Action int i= Integer parseInt(str); Converts string to primitive integer

long l= Long parseLong(str); Converts string to primitive long

1. Converting Primitive Numbers to Object Numbers

2. Converting Object Numbers to Primitive Numbers

3. Converting Numbers to String

4. Convert String Object to Numeric Object

5. Converting Numeric String to Primitive Numbers

Autoboxing and Unboxing

The Autoboxing and unboxing feature, introduced in J2SE 5.0, facilitates the process of handling

primitive data types in collections. We can use this feature to convert primitive data types to

wrapper class types automatically. The compiler generates a code implicitly to convert primitive

type to the corresponding wrapper class type and vice-versa. For example, consider the following

statements:

Double d = 98.42;

double dbl = d.doubleValue();

Using the Autoboxing and Unboxing feature, we can rewrite the above code as

:-

Double d = 98.42;

double dbl = d;

How, the java compiler provides restrictions to perform the following conversion:-

Convert from null type to any primitive type.

Convert to the null type other than the identify conversion.

Convert from any class type C to any array type if C is not object.

1. Vector Without using Autoboxing and Unboxing

2. Vector With using Autoboxing and Unboxing

Nesting of Methods

We discussed earlier that a method of a class can be called only by an object of that class (or class

itself, in the case of static methods) using the dot operator. However, there is an exception to

this. A method can be called by using only its name by another method of the same class. This is

known as nesting of methods.

Program illustrates the nesting of methods inside a class. The class Nesting defines one

constructor and two methods, namely largest () and display (). The method display () calls the

method largest () to determine the largest of the two numbers and then displays the result.

1. Nesting of Methods

2. Another Example

A method can call any number of methods. It is also possible for a called method to call another

method. That is, method1 may call method2, which in turn may call method3.

Thank you