java二重循环

若有3个班级各4名学员参赛，如何计算每个班级参赛学员的平均分？

        int total=0;
        int[] calss=new int[3];
        for (int i=0;i<3;i++)
        {
            Scanner scanner=new Scanner(System.in);
            System.out.println("请输入第"+(i+1)+"的班级成绩");
//            calss[i]=scanner.nextInt();
            int[] score=new int[4];
            for (int z=0;z<4;z++)
            {
                Scanner scanner1=new Scanner(System.in);
                System.out.println("请输入第"+(z+1) +"学员的考试成绩");
                score[z]=scanner.nextInt();
                total=total+score[z];
            }
            System.out.println(total/4);
        }

如何用*打印矩形图案？

        for (int i=0;i<5;i++)
        {
            for (int z=0;z<5;z++)
            {
                System.out.print("*\t");
            }
            System.out.println("");
        }

打印倒直角三角形

        for (int m=5;m>0;m--)
        {
            for (int i=0;i<m;i++)
            {
                System.out.print("*\t");
            }
            System.out.println(" ");
        }

打印九九乘法表

       for (int i=0;i<9;i++)
        {
            for (int z=0;z<1+i;z++)
            {
                System.out.print((i+1)+"*"+(z+1)+"="+(i+1)*(z+1)+"\t");
            }
            System.out.println("  ");