java程序设计求最值和均值

public class Test1 {
public static void main(String args[]){
int i;
double sum=0.0;
double max=0.0;

double a[]=new double[20];
for(i=0;i<20;i++){
a[i]=Math.random()*100;
System.out.printf("    %.2f",a[i]);
if((i+1)%3==0)
System.out.println();
sum+=a[i]/20;
}
System.out.println();
System.out.printf("平均成绩是:%.2f.",sum);
System.out.println();
for(i=0;i<20;i++){
if(a[i]>max)
max=a[i];
}
System.out.printf("最高分是：%.2f.",max);
System.out.println();
double min=a[0];
for(i=1;i<20;i++){
if(a[i]<min)
min=a[i];
}
System.out.printf("最低分是：%.2f.",min);
}