biginteger in java

// Java program to find large factorials using BigInteger 
import java.math.BigInteger; 
import java.util.Scanner; 
public class Example 
    // Returns Factorial of N 
    static BigInteger factorial(int N) 
        // Initialize result 
        BigInteger f = new BigInteger("1"); // Or BigInteger.ONE 
        // Multiply f with 2, 3, ...N 
        for (int i = 2; i <= N; i++) 
            f = f.multiply(BigInteger.valueOf(i)); 
        return f; 
    // Driver method 
    public static void main(String args[]) throws Exception 
        int N = 20; 
import java.math.BigInteger;
BigInteger f = new BigInteger("1");import java.math.BigInteger;public class ReplaceAllExample{  
public static void main(String args[]){  
String s1="Google is a very good website";  
String replaceString=s1.replaceAll("a","e");//replaces all occurrences of "a" to "e"  
}}  public static void arraycopy(Object source_arr, int sourcePos,
                            Object dest_arr, int destPos, int len)
Parameters : 
source_arr : array to be copied from
sourcePos : starting position in source array from where to copy
dest_arr : array to be copied in
destPos : starting position in destination array, where to copy in
len : total no. of components to be copied.