Java Data Types Array String and its Functions

JAVA have eight fundamental data types divided in four groups:--

Group                                                                                   Data types

Integer                                                                                 byte(8 bits), short(16 bits), int(32bits), long(64 bits)

Floating Point                                                                    float(32 bits), double(64 bits)

Character                                                                            char(16 bits)

Boolean                                                                               boolean(compiler deprndent)

Variable Declaration in Java:--

Syntax :-- 

                                Data_type   variable_name;

                e.g.        int a;         char c;                   float f;

Taking input in java:--

To take input We have to make a object of a Scanner class (Defined  in java.util  package)

import java.util.*; //importing util package to use scanner class

public class abc

{

      public static void main(String as[])

      {

            Scanner in=new Scanner(System.in); //object of scanner class //system.in is for system input

            byte b;

            short s;

            int i;

            long l;

            float f;

            double d;

           

            //taking input using object of scanner class and its function

           

            b=in.nextByte();

            s=in.nextShort();

            i=in.nextInt();

            l=in.nextLong();

            f=in.nextFloat();

            d=in.nextDouble();

            System.out.println("byte value=="+b);

            System.out.println("short value=="+s);

            System.out.println("int value=="+i);

            System.out.println("long value=="+l);

            System.out.println("float value=="+f);

            System.out.println("double value=="+d);

      }

}

Array and String

Declaring Array in java:--

int ar[]=new ar[5];

input in array:--

for(int i=0;i<5;i++)

{

      ar[i]=in.nextInt();//in is object of scanner class

}

Declaring a string in Java:--

String s=new String(); //here String is a class and s is object //of string class

Input in String:--

s=in.nextLine();

coping a string in to other string:--

String s1=new String(“hello”);

String s2=new String(s1);//hello is copied to s2

String s3=new String();

S3=s2;//again hello is copied to s3;

Passing a character array in string:--

char ch[]={'a','b','c','d'};

String ss=new String(ch);//abcd is copied to ss

String functions

import java.util.*; //importing util package to use scanner class

public class abc

{

      public static void main(String as[])

      {

            Scanner in=new Scanner(System.in); //object of scanner class 
//system.in is for system input

            String s1=new String();

            String s2=new String();

            System.out.println("enter any string");

            s1=in.nextLine();

           

            //finding length of string s1

            int l=s1.length();

            System.out.println("length of string=="+l);

           

            //taking a character from any index say 2  index is always less by
 //one to position

            char c=s1.charAt(2);

            System.out.println("character at index two=="+c);

           

            //checking  equality of two string

            s2="abc";

           

            if(s2.equals("Abc"))//equal() returns false because abc is not equal 
//to Abc (A is upper case)

            {

                  System.out.println("string is not equal");

            }

           

            if(s2.equalsIgnoreCase("Abc"))//equalIgnorecase() returns
 //ture because it ignore case

            {

                  System.out.println("strings are equal");

            }

           

            //comparing two string

            l=s2.compareTo(s1);//value of l will be 0 if s1==s2  other wise non
 //zero value

            l=s2.compareToIgnoreCase(s1);//ignore the case

           

            //Adding one string at end of other string

            s1=s1.concat(s2);//s2 will be added at the end of s1

            System.out.println(s1);

           

            //convert string in upper case

            s1=s1.toUpperCase();

            System.out.println(s1);

           

            //convert string in lower case

            s1=s1.toLowerCase();

            System.out.println(s1);

      }

}