Check if string contains valid number example

1. /*
           Check if string contains valid number example.
           This example shows how to check if string contains valid number
           or not using parseDouble and parseInteger methods of
           Double and Integer wrapper classes.
   */
   
   
   public class CheckValidNumberExample {
   
   
           public static void main(String[] args) {
   
   
                   String[] str = new String[]{“10.20”, “123456”, “12.invalid”};
   
   
                   for(int i=0 ; i < str.length ; i ++)
                   {
   
   
                           if( str[i].indexOf(“.”) > 0 )
                           {
   
   
                                   try
                                   {
                                           /*
                                            * To check if the number is valid decimal number, use
                                            * double parseDouble(String str) method of
                                            * Double wrapper class.
                                            *
                                            * This method throws NumberFormatException if the
                                            * argument string is not a valid decimal number.
                                            */
                                           Double.parseDouble(str[i]);
                                           System.out.println(str[i] + ” is a valid decimal number”);
                                   }
                                   catch(NumberFormatException nme)
                                   {
                                           System.out.println(str[i] + ” is not a valid decimal number”);
                                   }
   
   
                           }
                           else
                           {
                                   try
                                   {
                                           /*
                                            * To check if the number is valid integer number, use
                                            * int parseInt(String str) method of
                                            * Integer wrapper class.
                                            *
                                            * This method throws NumberFormatException if the
                                            * argument string is not a valid integer number.
                                            */
   
   
                                           Integer.parseInt(str[i]);
                                           System.out.println(str[i] + ” is valid integer number”);
                                   }
                                   catch(NumberFormatException nme)
                                   {
                                           System.out.println(str[i] + ” is not a valid integer number”);
                                   }
                           }
                   }
   
   
           }
   }
   
   
   
   /*
   Output would be
   10.20 is a valid decimal number
   123456 is valid integer number
   12.invalid is not a valid decimal number
   */

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A program to find whether no. is palindrome or not

Example : Input – 12521 is a palindrome no. Input – 12345 is not a palindrome no. */

class Palindrome
{
public static void main(String args[])
{
int num = Integer.parseInt(args[0]);
int n = num; //used at last time check
int reverse=0,remainder;
while(num > 0)
{
remainder = num % 10;
reverse = reverse * 10 + remainder;
num = num / 10;
}
if(reverse == n)
System.out.println(n+” is a Palindrome Number”);
else
System.out.println(n+” is not a Palindrome Number”);
}
}

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A program to Find whether number is Prime or Not

class PrimeNo
{
public static void main(String args[])
{
int num = Integer.parseInt(args[0]);
int flag=0;
for(int i=2;i<num;i++)
{
if(num%i==0)
{
System.out.println(num+” is not a Prime Number”);
flag = 1;
break;
}
}
if(flag==0)
System.out.println(num+” is a Prime Number”);
}
}

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Display Triangle as follow

1 2 3 4 5 6 7 8 9 10 … N */

class Output1{
public static void main(String args[])
{
int c=0;
int n = Integer.parseInt(args[0]);
loop1: for(int i=1;i<=n;i++)
{
loop2: for(int j=1;j<=i;j++)
{
if(c!=n)
{
c++;
System.out.print(c+” “);
}
else
break loop1;
}
System.out.print(“\n”);
}
}
}

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A program to find average of consecutive N Odd no. and Even no

class EvenOdd_Avg{
public static void main(String args[]){
int n = Integer.parseInt(args[0]);
int cntEven=0,cntOdd=0,sumEven=0,sumOdd=0;
while(n > 0){
if(n%2==0){
cntEven++;
sumEven = sumEven + n;
}
else{
cntOdd++;
sumOdd = sumOdd + n;
}
n–;
}
int evenAvg,oddAvg;
evenAvg = sumEven/cntEven;
oddAvg = sumOdd/cntOdd;
System.out.println(“Average of first N Even no is “+evenAvg);
System.out.println(“Average of first N Odd no is “+oddAvg);
}
}

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A program to generate Harmonic Series

Example : Input – 5 Output – 1 + 1/2 + 1/3 + 1/4 + 1/5 = 2.28 (Approximately) */
 
class HarmonicSeries
{
public static void main(String args[])
{
int num = Integer.parseInt(args[0]);
double result = 0.0;
while(num > 0)
{
result = result + (double) 1 / num;
num–;
}
System.out.println(“Output of Harmonic Series is “+result);
}
}

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Switch case demo

Example : Input – 124 Output – One Two Four */

class SwitchCaseDemo{
public static void main(String args[])
{
try
{
int num = Integer.parseInt(args[0]);
int n = num; //used at last time check
int reverse=0,remainder;
while(num > 0)
{
remainder = num % 10;
reverse = reverse * 10 + remainder;
num = num / 10;
}
String result=””; //contains the actual output
while(reverse > 0)
{
remainder = reverse % 10;
reverse = reverse / 10;
switch(remainder)
{
case 0 :
result = result + “Zero “;
break;
case 1 :
result = result + “One “;
break;
case 2 :
result = result + “Two “;
break;
case 3 :
result = result + “Three “;
break;
case 4 :
result = result + “Four “;
break;
case 5 :
result = result + “Five “;
break;
case 6 :
result = result + “Six “;
break;
case 7 :
result = result + “Seven “;
break;
case 8 :
result = result + “Eight “;
break;
case 9 :
result = result + “Nine “;
break;
default:
result=””;
}
}
System.out.println(result);
}catch(Exception e){
System.out.println(“Invalid Number Format”);
}
}
}

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A program to find whether given no. is Armstrong or not

Example : Input – 153 Output – 1^3 + 5^3 + 3^3 = 153, so it is Armstrong no. */

class Armstrong
{
public static void main(String args[])
{
int num = Integer.parseInt(args[0]);
int n = num; //use to check at last time
int check=0,remainder;
while(num > 0)
{
remainder = num % 10;
check = check + (int)Math.pow(remainder,3);
num = num / 10;
}
if(check == n)
System.out.println(n+” is an Armstrong Number”);
else
System.out.println(n+” is not a Armstrong Number”);
}
}

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A program to Display Invert Triangle using while loop

Example: Input – 5 Output : 5 5 5 5 5 4 4 4 4 3 3 3 2 2 1
class InvertTriangle
{
public static void main(String args[])
{
int num = Integer.parseInt(args[0]);
while(num > 0)
{
for(int j=1;j<=num;j++)
{
System.out.print(” “+num+” “);
}
System.out.print(“\n”);
num–;
}
}
}
 

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A program to convert given no. of days into months and days.(Assume that each month is of 30 days)

Example : Input – 69 Output – 69 days = 2 Month and 9 days */

class DayMonthDemo

{
public static void main(String args[])

{
int num = Integer.parseInt(args[0]);
int days = num%30;
int month = num/30;
System.out.println(num+” days = “+month+” Month and “+days+” days”);
}

}

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A program to Swap the values

class Swap{
public static void main(String args[]){
int num1 = Integer.parseInt(args[0]);
int num2 = Integer.parseInt(args[1]);
System.out.println(“\n***Before Swapping***”);
System.out.println(“Number 1 : “+num1);
System.out.println(“Number 2 : “+num2); //Swap logic
num1 = num1 + num2;
num2 = num1 – num2;
num1 = num1 – num2;
System.out.println(“\n***After Swapping***”);
System.out.println(“Number 1 : “+num1);
System.out.println(“Number 2 : “+num2);
}
}

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A program to find SUM AND PRODUCT of a given Digit

class Sum_Product_ofDigit{
public static void main(String args[]){
int num = Integer.parseInt(args[0]); //taking value as command line argument.
int temp = num,result=0; //Logic for sum of digit
while(temp>0){
result = result + temp;
temp–;
}
System.out.println(“Sum of Digit for “+num+” is : “+result); //Logic for product of digit
temp = num;
result = 1;
while(temp > 0){
result = result * temp;
temp–;
}
System.out.println(“Product of Digit for “+num+” is : “+result);
}
}

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A program to display a greet message according to Marks obtained by student

class SwitchDemo{
public static void main(String args[]){
int marks = Integer.parseInt(args[0]); //take marks
as command line argument.
switch(marks/10){
case 10:
case 9:
case 8:
System.out.println(“Excellent”);
break;
case 7:
System.out.println(“Very Good”);
break;
case 6:
System.out.println(“Good”);
break;
case 5:
System.out.println(“Work Hard”);
break;
case 4:
System.out.println(“Poor”);
break;
case 3:
case 2:
case 1:
case 0:
System.out.println(“Very Poor”);
break;
default:
System.out.println(“Invalid value Entered”);
}
}
}

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A Program that will read a float type value from the keyboard and print the following output

/*Small Integer not less than the number. Given Number. Largest Integer not greater than the number. */
class ValueFormat{
public static void main(String args[]){
double i = 34.32; //given number
System.out.println(“Small Integer not greater than the number :”+Math.ceil(i));
System.out.println(“Given Number : “+i);
System.out.println(“Largest Integer not greater than the number :”+Math.floor(i));
}

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To Find Minimum of Two Numbers using conditional operator

/* To find minimum of 2 Numbers using ternary operator */
class Minoftwo{
public static void main(String args[]){ //taking value as command line argument. //Converting String format to Integer value
int i = Integer.parseInt(args[0]);

int j = Integer.parseInt(args[1]);
int result = (i<j)?i:j;
System.out.println(result+” is a minimum value”);
}
}

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Find Maximum of Two Numbers

/* To Find Maximum of 2 Numbers using if else */
class Maxoftwo{
public static void main(String args[]){  
//taking value as command line argument. //Converting String format to Integer value
 
int i = Integer.parseInt(args[0]);
int j = Integer.parseInt(args[1]);
if(i > j)
System.out.println(i+” is greater than “+j);
else
System.out.println(j+” is greater than “+i);
}
}

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pyramid of numbers using for loops

/* Generate Pyramid For a Given Number Example This Java example shows how to generate a pyramid of numbers for given number using for loop example. */
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class GeneratePyramidExample {
public static void main (String[] args) throws Exception{
BufferedReader keyboard = new BufferedReader (new
InputStreamReader(System.in));
System.out.println(“Enter Number:”);
int as= Integer.parseInt (keyboard.readLine());
System.out.println(“Enter X:”);
int x= Integer.parseInt (keyboard.readLine());
int y = 0;
for(int i=0; i<= as ;i++){
16
for(int j=1; j <= i ; j++){
System.out.print(y + “\t”);
y = y + x;
}
System.out.println(“”);
}
}
} /* Output of this example would be Enter Number: 5 Enter X: 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 ———————————————- Enter Number: 5 Enter X: 2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 ———————————————- Enter Number: 5 Enter X: 3 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 */

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Factorial of a number using recursion

/*This program shows how to calculate Factorial of a number using recursion function. */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class JavaFactorialUsingRecursion {
public static void main(String args[]) throws NumberFormatException,
IOException{
System.out.println(“Enter the number: “); //get input from the user
BufferedReader br=new BufferedReader(new
InputStreamReader(System.in));
int a = Integer.parseInt(br.readLine()); //call the recursive function to generate factorial
int result= fact(a);
System.out.println(“Factorial of the number is: ” + result);
}
static int fact(int b)
{
if(b <= 1) //if the number is 1 then return 1
return 1;
else //else call the same function with the value – 1
return b * fact(b-1);
}
} /* Output of this Java example would be Enter the number: 5 Factorial of the number is: 120 */

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Calculate Circle Area using radius

This program shows how to calculate
area of circle using it’s radius.
 
Example:-
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class CalculateCircleAreaExample {
public static void main(String[] args) {
int radius = 0;
System.out.println(“Please enter radius of a circle”);
try
{
//get the radius from console
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
radius = Integer.parseInt(br.readLine());
}
//if invalid value was entered
catch(NumberFormatException ne)
{
System.out.println(“Invalid radius value” + ne);
System.exit(0);
}
catch(IOException ioe)
{
System.out.println(“IO Error :” + ioe);
System.exit(0);
}
/*
* Area of a circle is
* pi * r * r
* where r is a radius of a circle.
*/
//NOTE : use Math.PI constant to get value of pi
double area = Math.PI * radius * radius;
System.out.println(“Area of a circle is ” + area);
}
}

---

Output:-
Please enter radius of a circle
19
Area of a circle is 1134.1149479459152

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Nested Switch

This example shows how to use nested switch statements in a
java program.
Example:-
public class NestedSwitchExample {
public static void main(String[] args) {
/*
* Like any other Java statements, switch statements
* can also be nested in each other as given in
* below example.
*/
int i = 0;
int j = 1;
switch(i)
{
case 0:
switch(j)
{
case 0:
System.out.println(“i is 0, j is 0”);
break;
case 1:
System.out.println(“i is 0, j is 1”);
break;
default:
System.out.println(“nested default
case!!”);
}
break;
default:
System.out.println(“No matching case found!!”);
}
}
}

---

Output:-
i is 0, j is 1

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Reversed pyramid using for loops & decrements operator

Java Pyramid 5 Example
This Java Pyramid example shows how to generate pyramid or triangle
like given below using for loop.
12345
1234
123
12
1

Example:-
public class JavaPyramid5 {
public static void main(String[] args) {
for(int i=5; i>0 ;i–){
for(int j=0; j < i; j++){
System.out.print(j+1);
}
System.out.println(“”);
}
}
}

---

Output:-
12345
1234
123
12
1

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Pyramid of stars using nested for loops

/*
Java Pyramid 1 Example
This Java Pyramid example shows how to generate pyramid or triangle
like given below using for loop.
*
**
***
****
*****
*/

Example:-
public class JavaPyramid1 {
public static void main(String[] args) {
for(int i=1; i<= 5 ;i++){
for(int j=0; j < i; j++){
System.out.print(“*”);
}
//generate a new line
System.out.println(“”);
}
}
}

---

Output:-
*
**
***
****
*****

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Generate prime numbers between 1 & given number

Prime Numbers Java Example
This Prime Numbers Java example shows how to generate prime numbers
between 1 and given number using for loop.

Example:-
public class GeneratePrimeNumbersExample {
public static void main(String[] args) {
//define limit
int limit = 100;
System.out.println(“Prime numbers between 1 and ” + limit);
//loop through the numbers one by one
for(int i=1; i < 100; i++){
boolean isPrime = true;
//check to see if the number is prime
for(int j=2; j < i ; j++){
if(i % j == 0){
isPrime = false;
break;
}
}
// print the number
if(isPrime)
System.out.print(i + ” “);
}
}
}
Output:-
Prime numbers between 1 and 100
1 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 8

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Palindrome Number

/*
This program shows how to check for in the given list of numbers
whether each number is palindrome or not
*/
public class JavaPalindromeNumberExample {
public static void main(String[] args) {
//array of numbers to be checked
int numbers[] = new int[]{121,13,34,11,22,54};
//iterate through the numbers
for(int i=0; i < numbers.length; i++){
int number = numbers[i];
int reversedNumber = 0;
int temp=0;
/*
* If the number is equal to it’s reversed number, then
* the given number is a palindrome number.
*
* For ex,121 is a palindrome number while 12 is not.
*/
//reverse the number
while(number > 0){
temp = number % 10;
number = number / 10;
reversedNumber = reversedNumber * 10 + temp;
}
if(numbers[i] == reversedNumber)
System.out.println(numbers[i] + ” is a palindrome”);
else
System.out.println(numbers[i] + ” not a palindrome “);
}
}
}
/*
Output:-
121 is a palindrome number
13 is not a palindrome number
34 is not a palindrome number
11 is a palindrome number
22 is a palindrome number
54 is not a palindrome number
*/

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Fibonacci Series

/* Fibonacci Series Java Example
This Fibonacci Series Java Example shows how to create and print
Fibonacci Series using Java.
*/
public class JavaFibonacciSeriesExample {
public static void main(String[] args) {
//number of elements to generate in a series
int limit = 20;
long[] series = new long[limit];
//create first 2 series elements
series[0] = 0;
series[1] = 1;
//create the Fibonacci series and store it in an array
for(int i=2; i < limit; i++){
series[i] = series[i-1] + series[i-2];
}
//print the Fibonacci series numbers
System.out.println(“Fibonacci Series upto ” + limit);
for(int i=0; i< limit; i++){
System.out.print(series[i] + ” “);
}
}
}
/*
Output:-
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181
*/

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Compare Two Numbers using else-if

/*
Compare Two Numbers Java Example
This Compare Two Numbers Java Example shows how to compare two numbers
using if else if statements.
*/
public class CompareTwoNumbers {
public static void main(String[] args) {
//declare two numbers to compare
int num1 = 324;
int num2 = 234;
if(num1 > num2){
System.out.println(num1 + ” is greater than ” + num2);
}
else if(num1 < num2){
System.out.println(num1 + ” is less than ” + num2);
}
else{
System.out.println(num1 + ” is equal to ” + num2);
}
}
}
/*
Output:-
324 is greater than 234
*/

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Factorial of a number

This program shows how to calculate Factorial of a number.
*/
public class NumberFactorial {
public static void main(String[] args) {
int number = 5;
/*
* Factorial of any number is! n.
* For example, factorial of 4 is 4*3*2*1.
*/
int factorial = number;
for(int i =(number – 1); i > 1; i–)
{
factorial = factorial * i;
}
System.out.println(“Factorial of a number is ” + factorial);
}
}
/*
Output of the Factorial program would be
Factorial of a number is 120
*/

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If , else and nested if/else Statement

• If statement is a compare a statement and equality two number.
• Here, we are check a if / else condition.

Example:-
<?php
$number1=10;
$number2=20;
if($number1==$number2)
{
echo “Two number are equal <br>”;
}
else if ($number2>$number1)
{
echo “number2 is greater than number1 <br>”;
}
else
{
echo”Two number are not equal <br>”;
}
?>

OUTPUT:-
number2 is greater than number1

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Arithmetic operation

• In arithmetic operation we are use a four operator

             —>ADD (+)
             —>SUBTRACT (-)
             —>PRODUCT(*)
             —>DIVIDE (/)

• Here we are see a perform all operation.

Example:-
<?php
$number1=1009;
$number2=2003;
echo”ADD<br>”;
echo $number1+$number2 .'<br>’;
echo”SUBTRACT<br>”;
echo $number1-$number2.'<br>’;
echo”PRODUCT<br>”;
echo $number1*$number2.'<br>’;
echo”DIVIDE<br>”;
echo $number1/$number2.'<br>’;
?>

OUTPUT:-
ADD
3012
SUBTRACT
-994
PRODUCT
2021027
DIVIDE
0.50374438342486

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Concatenation operator and Escape sequences

Here, we are use a Google link through a “HTML”

Example:-
<?php
$value=25;
$name=”Castor Classes”;
echo “Hello=$name <br>”;    //<br> is use for a next line.
echo ‘Hello=’ . $name . ‘<br>’;
$google=’Google Link’;
echo ‘<a href="http://www.google.com">’.$google.'</a> <br>’;  //This is a HTML code.
echo ‘It’s a nice day’;
?>

OUTPUT:-
Hello=Castor Classes
Hello=Castor Classes
Google Link
It’s a nice day

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Variable Declare

• PHP variable must begin with a “$” sign.
• Case-sensitive ($Boo!=$b00 !=$BOo)
• Global and locally-scoped variable

            Global variable can be used anywhere
            Local variable restricted to a function or class

• certain variable names reserved by PHP

            Form variable ($_POST,$_GET)
            Server variable ($_SERVER)
            Etc.



Example:-
<?php
$value=25;
$name=”Castor Classes”;
$value=($value*8);
echo “$name”;
echo $name,$value;
?>

OutPut:-
Castor ClassesCastor Classes200

Here, $value is use for integer variable and $name is string variable.

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List of even numbers

List Even Numbers Java
This List Even Numbers Java Example shows how to find and list even
numbers between 1 and any given number.
 
*/
public class ListEvenNumbers {
public static void main(String[] args) {
//define limit
int limit = 50;
System.out.println(“Printing Even numbers between 1 and ” +
limit);
for(int i=1; i <= limit; i++){
// if the number is divisible by 2 then it is even
if( i % 2 == 0){
System.out.print(i + ” “);
}
}
}
}
/*
Output of List Even Numbers Java Example would be
Printing Even numbers between 1 and 50
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

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Recursion

–>Recursion is a process in which a method calls itself continuously. 
A method in java that calls itself is called recursive method.

–>Syntax:-
returntype methodname()
{
//code to be executed
methodname();          //calling same method
}

Example:-
Public Class MyClass
{
// N!=N*(N-1)*(N-2)*………*1.
// 5=5*4*3*2*1
public static int factorial (int N)
{
if(N<=1)
return 1;
else (N*factorial(N-1));     //Call itself method
}
public static void main(string[] args)
System.out println(factorial(5));
}
}

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Difference between ArrayList and LinkedList

ArrayList	LinkedList
1) ArrayList internally uses dynamic array to store the elements.	LinkedList internally uses doubly linked list to store the elements.
2) Manipulation with ArrayList is slow because it internally uses array. If any element is removed from the array, all the bits are shifted in memory.	Manipulation with LinkedList is faster than ArrayList because it uses doubly linked list so no bit shifting is required in memory.
3) ArrayList class can act as a list only because it implements List only.	LinkedList class can act as a list and queue both because it implements List and Deque interfaces.
4) ArrayList is better for storing and accessing data.	LinkedList is better for manipulating data.

Example:-
 Public Class MyClass{
public static void main(String args[])
{
List<String> MyList=new ArrayList<String>();   //creating arraylist    
MyList.add(“Ravi”);        //Adding object in arraylist    
MyList.add(“Vijay”);
MyList.add(“Ravi”);
MyList.add(“Ajay”);
List<String> MyList2=new LinkedList<String>();       //creating linkedlist    
MyList2.add(“James”);     //adding object in linkedlist   
MyList2.add(“Serena”);
MyList2.add(“Swati”);
MyList2.add(“Junaid”);
System.out.println(“arraylist: “+MyList);
System.out.println(“linkedlist: “+MyList2);                                                                                            }

}

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