当我尝试解析字符串数组索引时出现空指针异常。我该如何解决?谢谢
public class studentclass {
public static void main(String[] args){
Scanner scan = new Scanner(System.in);
String[][] student = new String[10][];
Double[][] results = new Double[10][];
Double[] total = new Double[10];
String tableln = "";
for(int index = 0; index < student.length; index++){
System.out.println("\nPlease enter student " + (index+1) + "'s details");
String userinput = scan.nextLine();
student[index] = userinput.split(",");
//converts string array in to double array but receiving null pointer exception
results[index][0] = Double.parseDouble(student[index][2]);
results[index][1] = Double.parseDouble(student[index][3]);
results[index][2] = Double.parseDouble(student[index][4]);
results[index][3] = Double.parseDouble(student[index][5]);
total[index] = (results[index][0]*0.1+results[index][1]*0.4+
results[index][2]*0.3+results[index][3]*0.2);