用一段代码记住一个知识点

public class Test_04 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Random r = new Random();
        System.out.println("请输入班级总组数:");
        int team = sc.nextInt();
        System.out.println("请输入每组人数:");        
        int member = sc.nextInt();
        //定义四个变量来记录全班的不及格数和,总分组最高平均分,全班平均分;
        double result;
        double max=0;
        int fail=0;
        int sum = 0;
        //定义一个二维数组
        int [][] arr =new int[team][member];
        for(int j = 0;j<team;j++){
                int sum1=0;
                int fail1=0;
                double every=0;
                for (int i =0; i<member; i++){
                    arr[j][i]=r.nextInt(101);
                    
                    if (arr[j][i]<=60){
                        fail1++;
                    }
                    sum1+=arr[j][i];
                    every = sum1/(member*1.0);
                    max = max>every?max:every;
                }
                System.out.println("第"+(j+1)+"组不及格人数:"+fail1+'
'+"第"+(j+1)+"组平均分:"+every);
                fail+=fail1;
                sum += sum1;
        }
        System.out.println("班级中单组最高平均分为:"+max);
        System.out.println("班级中不及格人数为:"+fail);
        //System.out.println("班级总平均分为:"+(sum/(team*member*1.0)));
        result=(sum/(team*member*1.0));
        String re =String.format("%.2f",result);
        System.out.println("班级总平均分为:"+re);
    }
}

其中 String re = String.format("%.2f",result);

运用String的函数完成小数点之后的精确输出.

此知识点我要牢牢记住,今天就给忘了.