可以帮我看看吗？运行不了

Question

import java.util.Arrays;import java.util.Scanner;public class test5{ private static final long[] StuFirstThree = null; public static void main(String[] args){ Scanner input=new Scanner(System.in); System.out.println("请输入学员个数："); int numStu=input.nextInt(); int[] StuFirstThree=new int[numStu]; test5 guigod=new test5(); guigod.InputNum(numStu); } } public void InputNum(int length){ for(int i=0;i<=StuFirstThree.length;i++){ System.out.println("请输入第"+i+"个学生的成绩"); Scanner input=new Scanner(System.in); int numStua=input.nextInt(); StuFirstThree[i]=numStua; }} public void FirstNum(){ Arrays.sort(StuFirstThree); int k=0; for(int j=StuFirstThree.length-1;j>0;j--){ if(StuFirstThree[j]>100||StuFirstThree[j]<0){ continue; if(k>3){ break; } } }}