CORE JAVA(ch-4->creating user defined static members and wrapper classes )

Hey!guys this is hitesh,and today we'll learn to create user defined static members.

After that we will also see some basic concepts of data conversion using wrapper classes.

How we can create our own static members?

Create some class and create the static reference of your own classes then use anywhere.

import java.io.*;

import java.util.*;

public class My

{

    public static Scanner sc=new Scanner(System.in);

    public static BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

}

import static java.lang.System.*;

import java.io.*;

public class VoterTest1

{

    public static void main(String args[]) throws IOException

    {

        out.print("Name : ");

        String name=My.br.readLine();

        out.print("Age : ");

        int age=My.sc.nextInt();

       

        if(age>=18)

            out.printf("%s you can vote", name);

        else

            err.printf("%s you cannot vote",name);

    }

}

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Wrapper Classes

Special classes corresponding to data types which provides advance functions on the data types and data conversion from string to value types

Data type       Wrapper Class

byte                 Byte

short                Short

int                    Integer

long                 Long

float                 Float

double             Double

char                 Character

boolean           Boolean

Example 1

WAP to input a number and show that number in decimal, octal, hexa and binary

import java.util.Scanner;

public class WrapperTest1

{

    public static void main(String args[])

    {

        Scanner s=new Scanner(System.in);

        System.out.print("Enter a number : ");

        int num=s.nextInt();

        System.out.println("Decimal is : "+num);

        System.out.println("Hexa is : "+Integer.toHexString(num));

        System.out.println("Binar is : "+Integer.toBinaryString(num));

        System.out.println("Octal is : "+Integer.toOctalString(num));

    }

}

Example 2

WAP to input a character and check it to be alphabet, digit or special character

Use read() method of System.in to read a character

            int read() throws IOException

public class WrapperTest2

{

    public static void main(String args[]) throws java.io.IOException

    {

        System.out.print("Enter a character : ");

        char ch=(char)System.in.read();

       

        if(Character.isLetter(ch))

            System.out.printf("%c is an alphabet",ch);

        else if(Character.isDigit(ch))

            System.out.printf("%c is a digit", ch);

        else

            System.out.printf("%c is special character", ch);

    }

}

Data conversion from string to value type

datatype variable=wrapperclass.parseDatatype(stringdata);

Example

WAP to input name and age of a person and check it to be valid voter.

import java.io.*;

public class Voter

{

    public static void main(String args[]) throws IOException

    {

        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

        System.out.print("Name : ");

        String name=br.readLine();

       

        System.out.print("Age : ");

        int age=Integer.parseInt(br.readLine());

       

        if(age>=18)

            System.out.printf("Dear %s you can vote",name);

        else

            System.out.printf("Dear %s you cannot vote",name);

    }

}

THAT's all about wrapper classes and we also learned about static members and to create them.

Thank you

Keep coding :)

Keep learning :)