为什么会出现提示输入的乱码呢

而且有时有有时能正常输出，dos里面那个错误我知道，搞不懂27行eclipse为什么会报

代码被吃了

import java.util.*;
public class Stu {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("请输入学生人数");
int renshu = in.nextInt();
System.out.println("请输入课程数目");
int courseNum = in.nextInt();// 课程数
String[] name = new String[renshu];// 接受姓名
String[] course = new String[courseNum];// 接受课程名
int[][] number = new int[renshu][courseNum];// 二维数组接受学生每门成绩
int[] sum = new int[renshu];
int[] avg = new int[renshu];
String[]str=new String[renshu];
for (int i = 0; i < course.length; i++) {
System.out.println("请输入第" + (i + 1) + "门课程的名字");
course[i] = in.next();
}
for (int i = 0; i < renshu; i++) {
int S = 0;
System.out.println("请输入学生的姓名");
name[i] = in.next();
String str11="";
for (int j = 0; j < courseNum; j++) {
System.out.println("请输入" + name[i] + course[j] + "的成绩");
number[i][j] = in.nextInt();// 存储特定学生特定成绩
S += number[i][j];
str11+=number[i][j]+"\t";
}
sum[i] = S;
avg[i] = S / courseNum;
str[i]=name[i]+"\t"+str11+sum[i]+"\t"+avg[i];
}
for(int i=0;i<sum.length-1;i++)
{
for(int j=0;j<sum.length;j++) {
int r=sum[j]; String r1=str[j];
sum[j]=sum[j+1]; str[j]=str[j+1];
sum[j+1]=r; str[j+1]=r1;
}
}
System.out.print("学生");
for (int i = 0; i < course.length; i++) {
System.out.print("\t" + course[i]);
}
System.out.print("\t总分\t平均分\t排行");
System.out.println();
for (int i = 0; i < renshu; i++) {
System.out.println(str[i]+"\t第"+(i+1)+"名");
/*System.out.print(name[i]);
for (int j = 0; j < courseNum; j++) {
System.out.println("\t" + number[i][j]);
}
System.out.print("\t" + sum[i]);
System.out.print("\t" + avg[i]);
System.out.print("\t" + avg[i]);
*/
}
}
}