finding average of numbers by passing elements of an array through console

Question

Actually I'm new to this group and also new to Java and I wanna know about how to pass array parameters through console and I ended up programming like this :

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class Average
  {
    public static void main(String []args)
    {
      int numbers[];

      try
       {
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      numbers =Integer.parseInt( br.readLine());
       }
      catch(NumberFormatException ne)
            {
                    System.out.println("Invalid input: " + ne);
                    System.exit(0);
            }
            catch(IOException ioe)
            {
                    System.out.println("I/O Error: " + ioe);
                    System.exit(0);
            }
        System.out.println(methodAverage());
            }


        public static int methodAverage(int...numbers)
        {
         int sum=0;
         int avg=0;

         for(int x:numbers)
         {
          sum+=x;
          avg=sum/numbers.length;
          return avg;
          }
          }
          }

and the error is

Average.java:13: error: incompatible types
numbers =Integer.parseInt( br.readLine());
         ^
required: int[]
found:    int
  1 error

I know that would come but I just tried
So I just wanna know about how to pass those numbers through console?

Answer 1

int numbers[];

As array is an object, you need to allocate it on heap using new as int numbers[] = new int[size]; .

Average.java:13: error: incompatible types
numbers =Integer.parseInt( br.readLine());

--> Integer.parseInt() returns integer and not an array, instead you can use :

for(int index=0; index<size; index++) {
    numbers[index] =Integer.parseInt( br.readLine()); // add exception handling code as above
}

You are using BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); to read values from console instead I recommend you to use Scanner class. Have a look on java.util.Scanner .

Answer 2

如果您使用它来运行该应用程序，则可以通过这种方式在命令行或终端中传递值数组

java SomeJavaFile.java 1,2,3,4,5

Answer 3

numbers = Integer.parseInt(br.readLine());

parserInt() returns a single integer, and numbers is an array. You need a loop.

As to your average() method, you might want to consider using floating-point maths. Otherwise, the average of 1 1 1 1 1 1 0 will come out as zero.

Answer 4

use ArrayList<Integer> numbers = new ArrayList<Integer> instead of int[] numbers ; and change numbers =Integer.parseInt( br.readLine()); to numbers.add(Integer.parseInt( br.readLine())); this aloows you nto read single integre each input line.

If you have a single line with more than one integer as input:

String[] nums = br.readLine().split(" ");
int[] numbers = new int[nums.length];
for(int i = 0; i < nums.length; i++) {
 numbers[i] = Integer.parseInt(nums[i]);
}

Answer 5

Please find the modified program to get the average.
I have used space as a separator when user enters the inputs.

package Test;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class Average
  {
    public static void main(String []args)
    {
     // int numbers;
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      String ip = null;
    try {
        ip = br.readLine();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
      String[] items=ip.split(" ");
      int[] results = new int[items.length];
      try
       {


      for (int i = 0; i < items.length; i++) {
          try {
              results[i] = Integer.parseInt(items[i]);
          } catch (NumberFormatException nfe) {};
      }
       }
      catch(NumberFormatException ne)
            {
                    System.out.println("Invalid input: " + ne);
                    System.exit(0);
            }
        System.out.println(methodAverage(results));
            }


        public static int methodAverage(int...numbers)
        {
         int sum=0;
         int avg=0;

         for(int x:numbers)
         {
          sum+=x;
          avg=sum/numbers.length;
          }
        return avg;
          }
          }