TestScores Critique

/** 
    Inputs 'n' test scores, then outputs the lowest
    (minimum), highest test score (maximum), average
    test score(average).
 
    Robert Studenic
    rs.nibbles at gmail.com
 */
 
import java.util.Scanner;
 
public class TestScores {
 
    public static void main(String[] args) {
 
	Scanner input = new Scanner(System.in);
 
	// Input # of tests and test scores.
	System.out.println("Input the number of tests to calculate: ");
	int testNum = input.nextInt();
	int i = 1;
	double max = 0;
	double min = 0;
	double avg = 0;
 
	while( i <= testNum){
	System.out.println("Input score for Test " + i + " : ");
        double test = input.nextDouble();
 
	// Test 'test' to see if it is a valid input.
	if(test < 0){
	    System.out.println("This is not a valid input. Program exiting.");
	    return;
	}	    
 
	// Test variables to check if this is initial while run.
	if(i == 1){
	    max = test;
	    min = test;
	    avg = test;
	}
 
	// Testing 'test' if it is lower than the current value for min.
	if(test < min)
	    min = test;
 
	// Testing 'test' if it is higher than the current value for max.
	if(test > max)
	    max = test;
 
	// Adding 'test' to the value of avg.
	if(i == 1);
	else 
	    avg += test;
 
	++i;
 
	}
	// Calculating average.
	avg = avg / testNum;
 
	// Output min, max, and avg.
	System.out.printf("The minimum for the " + testNum + " tests is " + min + ".\n");
	System.out.printf("The average for the " + testNum + " tests is " + avg + ".\n");
	System.out.printf("The maximum for the " + testNum + " tests is " + max + ".\n");
 
    }
}