Example of a method:

The codes:

import java.util.Scanner;

public class Sum
{
   public static void main(String[] args)
   {
    Scanner input = new Scanner(System.in);
    
    int [] A = {7,3,6,9,1,2,8,5,0,4};
    int [] B = new int[5];    
  
    System.out.println("Enter 5 numbers."); 
    for(int i=0; i < 5; i++)
           B[i]=input.nextInt();
    
    int maxA = getMax(A);  //Save a return value in a variable
                           //print it after you save the result
    System.out.printf("The maximum of A array is %d.\n", maxA);
    
    //You can call a method and print the return value immediately 
    System.out.printf("The maximum of B array is %d.\n", getMax(B));

   }
   
   /** Client provide any int array with any length
       getMax method will find the max number from the array
       and return it to client.
   */
   public static int getMax(int[] arr)
   {
       int n = arr.length;  //the number of elements in arr
       int max = arr[0];    //initialize max as the first element
       for(int i=1; i<n; i++) //Check from the second element
       {
           if(arr[i] > max)   //if element is larger than max,
              max = arr[i];   //overwrite the max
       }
       return max;
   }
}

Adding two more methods as below:

Call from main method:

The code:

   public static int getSum(int[] x)
   {
      int n = x.length;
      int sum = 0;
      for(int i=0; i<n; i++)
          sum +=x[i];
      return sum;
   }

   public static double getAvg(int[] y)
   {
       int n = y.length;
       int sum = getSum(y);
       double avg = (double) sum / n;
       return avg;
   }