import java.util.*;

public class StudentEbo {
    Student[] arr=new Student[0];
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        System.out.println("请输入学生人数：");
        StudentEbo.add(in.nextInt());
    }
    public static void add(int num){
        if(arr.length<num){
            Student[] tempArr=new Student[arr.length+1];
            Scanner in=new Scanner(System.in);
            Student st=new Student();
            System.out.println("请输入学生姓名：");
            st.setName(in.next());
            System.out.println("请输入学生年龄：");
            st.setAge(in.nextInt());
            st.setOn(arr.length+1);
            tempArr[arr.length]=st;
            arr=tempArr;
            printAll();
        }
    }
    public static void printAll(){
        System.out.println("\t编号\t姓名\t年龄\tjava\tC#\thtml\tsql\t总分\t平均分");
        for(int i=0;i<arr.length;i++){
            System.out.println("\t"+arr[i].getOn()+"\t"+arr[i].getName()+"\t"+arr[i].getAge()+"\t"+arr[i].getJava()+"\t"+arr[i].getC_shar()
                    +"\t"+arr[i].getHtml()+"\t"+arr[i].getSql()+"\t"+arr[i].getSum()+"\t"+arr[i].getAvg());
        }
    }
}

但是把tempArr的值赋给他了，该应会有tempArr的值才对啊..

这已经是一段完整的代码了..