java系统模块路径未与源代码14一起设置

Question

当我运行一个程序时，它要求用户输入（双数据类型），并在NetBeans中显示它们的平均值

System.out.println("Enter three numbers: ");
double num1 = sc.nextDouble();
double num2 = sc.nextDouble();
double num3 = sc.nextDouble();
double avg = (num1+num2+num3)/3.0;
System.out.println("The average of numbers " + num1 +" , " + num2 + " and " + num3 + " is :" + avg);```