public class Main {
public static double average(double[] array) {
double temp = 0;
double sum = 0;
for (int i = 0; i < array.length; i++) {
sum = sum + array[i];
}
temp = sum / array.length;
return temp;
}
public static void main(String[] args) {
File file = new File("C:/Users/15002/Desktop/文件/gongzuo.xlsx");
ArrayList<ArrayList<Object>> result = ExcelUtil.readExcel(file);
ArrayList<Double> result2 = null;
double rand[] = new double[50];
double av;
java.util.Random r = new java.util.Random();
for (int j = 0; j < 10000; j++) {
for (int i = 0; i < 50; i++) {
try {
rand[i] = Double.valueOf(result.get(r.nextInt(62080)).get(0).toString()).doubleValue();
} catch (NumberFormatException e) {
e.printStackTrace();
}
System.out.println(rand[i]);
av = average(rand);
System.out.print("平均值为:" + av);
result2.add(av);
}
}
}
}
运行结果:
12.0
Exception in thread "main" 平均值为:0.24java.lang.NullPointerException
at Main.main(Main.java:35)