How to make this program efficient?

Question

Hola Amigos, I'm trying to explore all the possibilities about comparing two arrays. I know the following code is O(n^2) is it possible to make it O(n) without recursion or is recursion the only way. I ask this because we are being taught recursion and I don't quite understand it. I don't see the relation from recursion taught in Discrete Math with the one taught in programming, Thanks.....
public class twoArrays
     public static int max = -1;
     public static int findMax(int oneArray [], int twoArray [])
          for (int i = 0 ; i < oneArray.length ; i ++)
               for ( int j = 0; j < twoArray.length ; j++)
                    max = Math.max(max,Math.max(oneArray,twoArray[j]));     
          return max;
     public static void main (String [] args)
          int[] a = {1,5,8,30,80,99,140,160,170,180,190,200};
          int[] b = {2,4,7,45,60,85,98,150,155,175,195,205};
          findMax(a,b);
          System.out.println("The highest value is: " + max);
Ah, one more thing the word "static" how can I call a method from a non-static context. Very confussing for me, thanks again.

Answer 1

To call a non-static method you can use an instance of the class.
Example:
public class twoArrays {
public static int max = -1;
public int findMax(int oneArray [], int twoArray []){//non-static
     for (int i = 0 ; i < oneArray.length ; i ++){
     for ( int j = 0; j < twoArray.length ; j++)                    max = Math.max(max,Math.max(oneArray,twoArray[j]));          }
     return max;
public static void main (String [] args)     {          
int[] a = {1,5,8,30,80,99,140,160,170,180,190,200};
int[] b = {2,4,7,45,60,85,98,150,155,175,195,205};
( new twoArrays() ).findMax(a,b);/*through an anonymous instance of the class, you can call findMax method */
System.out.println("The highest value is: " + max);          
Hope it will help you.
p.d.: max is initialized -1 cause then into findmax, you asure that max will never again has value -1 (the two arrays contains numbers > -1 )so max at least will be higher than -1.
Sorry for my english.
Saludos