To figure out what method does

hello
i am currently trying to figure out what a certain method does so as to proceed to annotate it, providing a post condition and loop invariant.
what i figured out:
on a positive and negative array and all positive x becomes positive upon the first time the minimum is encountered but when the array is all negative x and y are the sum of the elements
anyone see another approach to analyzing to this method?
thank you for your time

Code:

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public class funA{
    public static void functionOfA( int a[]){
        int MAXINT= Integer.MAX_VALUE;
        int x= MAXINT;
        int y= MAXINT;
        int i= 0;
        int n= a.length;

        while( i!= n){ 
            if( y== MAXINT){
                //y= MAXINT
                y= a[i];
                //y= a[i]
                x= min( x, y);
                //x= min(x,y)
                System.out.println("x: " +x + " y: "+ y);
                i= i+1;
                //y= a[i-1];
            } else{
                y= min( y+ a[i], a[i]);
                // y= min( y+ a[i], a[i]);
                x= min( x, y);
                //x= min( x, y);
                System.out.println("x: " +x + " y: "+ y);
                i= i+1;
                // y= min( y+ a[i-1], a[i-1]);
            } 
        }
        System.out.println( x+ " "+ y);
    }

    public static int min( int x, int y){
        if( x< y){
            return x;
        }
        else{
            return y;
        }
    }

    public static void main ( String args[]){
        int a[]= new int[] {0,-9,3,2,-4,3,-12,3,1};
        functionOfA( a);
        for( int i= 0; i< a.length; i++){
            System.out.print( a[i]+ " ");
        }
        System.out.println();
        System.out.println();
        int a2[]= new int[] {-9,-3,-10,-4,-2};
        functionOfA( a2);
        for( int i2= 0; i2< a2.length; i2++){
            System.out.print( a2[i2]+ " ");
        }
    }
}

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by the way this was the given:
1. int x = MAXINT; int y = MAXINT; int i = 0;
2. int a[n];
3. while i != n {
4. y = min(y + a[i], a[i]);
5. x = min(x, y);
6. i = i + 1;
7. }