How to specify the number of input data sets. (Java)-CodePudding

The first line is the number of data sets.

The second line is the data, where the first is the amount of data. and after that is data . such as

1 after specify amount of set. we have to input data 1 set follow below.

3 1 2 3 first number is How many data you have to input, for second ,third, and fourth is input.

And other example :

2

2 1 2

3 2 3 4

My problem : I don't now how to make input after I specify amount if set(first line) . I don't know how to do after input first line.

import java.util.Scanner;
public class average {
public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int  set = sc.nextInt();

    int count = 0, i = 1;
    double sum = 0 ;
    double avg;
    String str_num = sc.nextLine();
    String[] arr = str_num.split(" ");

    while (Integer.parseInt(arr[i]) != -1){
        sum  = Integer.parseInt(arr[i]);
        i  ;
        count  ;
    }
    avg = sum / count;
    System.out.printf("%.3f", avg);
 }
}

CodePudding user response：

public class Average {

    public static void main(String... args) {
        Scanner scan = new Scanner(System.in);
        List<int[]> data = readData(scan);
        double avg = calcAvg(data);
        System.out.format(Locale.ENGLISH, "%.3f\n", avg);
    }

    private static List<int[]> readData(Scanner scan) {
        int total = scan.nextInt();
        List<int[]> data = new ArrayList<>(total);

        for (int i = 0; i < total; i  ) {
            int[] dataLine = new int[scan.nextInt()];

            for (int j = 0; j < dataLine.length; j  )
                dataLine[j] = scan.nextInt();

            data.add(dataLine);
        }

        return data;
    }

    private static double calcAvg(List<int[]> data) {
        int sum = 0;
        int count = 0;

        for (int[] dataLine : data) {
            count  = dataLine.length;
            sum  = Arrays.stream(dataLine).sum();
        }

        return count == 0 ? 0 : (double)sum / count;
    }

}

Demo:

CodePudding user response：

I have written the instructions to get input, modify the needed data type and perform needed operations

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        // number of dataSets
        int dataSets = sc.nextInt();
        
        // getting input for each dataSet
        for(int i = 0; i < dataSets ; i  ) {
            // number of data in each dataset
            int n = sc.nextInt();
                
            int[] arr = new int[n 1];
            arr[0] = n; // first data indicates number of data in that dataset
                
            for(int j = 1 ; j < arr.length ; j  ) {
                // getting the input data 
                arr[j] = sc.nextInt(); 
            }
                
            System.out.println(Arrays.toString(arr));
        }
    }
}