import java.util.Scanner;

public class Factorial {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		System.out.print("Enter Number : ");
		int input = scanner.nextInt();
		
		System.out.println("Factorial Of " + input + " = " + factorial(input));
	}
	
	public static long factorial(int limit){
		long temp = 1;
		for(int i = 1; i <= limit; i++){
			temp = temp * i;
		}
		return temp;
	}

}

import java.util.ArrayList;

public class ArrayListToArray
{
    public static void main(String[] args)
    {
        ArrayList al = new ArrayList();

        //Add Elements
        al.add(new Integer(1));
        al.add(new Integer(10));
        al.add(new Integer(21));

        //Show contents
        System.out.println("Contents of Arraylist : " + al);

        //Get Array
        Object[] arr = al.toArray();

        //Print Array
        int sum = 0;
        for(Object x : arr)
        {
            System.out.println(x);
            sum += ((Integer)x).intValue(); //Converting object to int
        }

        System.out.println("Sum = " + sum);
    }
}

import java.util.*;

public class ArrayListDemo
{
    public static void main(String[] args)
    {
        ArrayList al = new ArrayList();
        System.out.println("Initial Size Of ArrayList : " + al.size());

        //Add elements to array list
        al.add("i");
        al.add("h");
        al.add("u");
        al.add("m");
        al.add("a");
        al.add("n");
        al.add("o");
        al.add("i");
        al.add("d");
        al.add(".");
        al.add("s");

        System.out.println("Size of ArrayList after additions : "+ al.size());

        //Contsnt of ArrayList
        System.out.println("Contents of ArrayList : " + al);

        //Remove Elements From ArrayList
        al.remove(".");
        al.remove(6);

        //Contents of ArrayList after removal
        System.out.println("Size of arraylist after removal : " + al.size());
        System.out.println("Contents After Removal : " + al);
    }
}

* A new instance of an Array can be created using the new keyword

* The elements in an Array can be sorted using sort() function

* An array element(s) can be modified using the fill() function. Fill function can be used with different constructors. Here we used to change the value of an array from index 2 to 6 by a value -1 as you can see in line 21.

import java.util.*;

public class ArrayDemo
{
    public static void main(String[] args)
    {
        int[] arr =new int[10];
        for(int i = 0; i < 10; i++)
        {
            arr[i] = -3 * i;
        }

        //Display, Sort, Display
        System.out.println("Original Contents Of Array");
        display(arr);
        Arrays.sort(arr);
        System.out.println("\nSorted Array");
        display(arr);

        //Fill & Display
        Arrays.fill(arr,2,6,-1);
        System.out.println("\nArray After Fill");
        display(arr);

        //Again Sorting
        Arrays.sort(arr);
        System.out.println("\nSorted Array");
        display(arr);

        //Location Of -9
        int index = Arrays.binarySearch(arr, -9);
        System.out.print("\n-9 is at location : " + index + "\n");

    }

    public static void display(int[] array)
    {
        for(int i = 0; i < array.length; i++)
        {
            System.out.print(array[i] + " ");
        }
    }
}

public class CommandLine
{
    public static void main(String[] args)
    {
        System.out.println("Arguments are");
        for(int i = 0; i<args.length; i++)
        {
            System.out.println(args[i]);
        }
    }
}

Save file as “CommandLine.java”
Compile the program as “javac CommandLine.java”
run program as “java CommadLine Hello World”
(All without quotes)

Here we entered the string “Hello World” as command line argument to the application while invoking it.  And this string will store in string array variable args[] that we just declared in our main method. We can pass  as many arguments as we wanted; just put a space between arguments.

class Addition
{
     public static void main(String[] args)
     {
           int a = 10;
           int b = 20;
           int c = a + b;

           System.out.println("Sum of " + a + " and b is : " + c);
     }
}

//Prints Hello World in console window
class HelloWorld
{
     public static void main(String[] args)
     {
           System.out.println("Hello World");
     }
}