Why is System.out.println not giving any output?

Question

I wrote a simple java program but it isn't giving any output. It just has to take array input and then print it but on running the program it doesn't produce any output and it is also consuming 60 MB of memory.

import java.util.*;
public class TestClass {
public static void main(String[] args) { 
    Election obj = new Election();
    obj.getVotes();
    obj.displayResult();
    }
}

class Election
{
  int num;
  int[] votes=new int[num];
  void getVotes()
  {
    Scanner sc=new Scanner(System.in);
    num=sc.nextInt();
    //for(int i:votes)
    for(int i=0;i<votes.length;i++)
      votes[i]=sc.nextInt();
  }
  void displayResult()
  {
    //for(int i:votes)
    for(int i=0;i<votes.length;i++)
    {
      System.out.println(votes[i]);
    }
  }
}

You don't initialize `num`, so it's 0. With that your loops run zero times, reading zero inputs, and producing zero output. — Robert, Feb 27 '18 at 21:19
`int num; int[] votes=new int[num];` What value do you think num is here? How many items can you put into that array? — takendarkk, Feb 27 '18 at 21:19

score 4 · Answer 1 · answered Feb 27 '18 at 21:19

This:

int num;
int[] votes=new int[num];

Creates an array with 0 elements. This code in getVotes():

Scanner sc=new Scanner(System.in);
num=sc.nextInt();

does not resize the array which was created when the Election class was instantiated.

So in displayResult() you have an empty votes array and, accordingly, no output.

score 0 · Answer 2 · answered Feb 27 '18 at 22:38

You have just to give a length to array you create.Below is the same code but I have initialyzed votes array with a lentgh of 5 Look below

public class testClass {

    public static void main(String[] args) {
         Election obj = new Election();
         obj.getVotes();
         obj.displayResult();
   }

}

 class Election
 {
  int num=5;
  int[] votes=new int[num];

  void getVotes()
  {
   Scanner sc=new Scanner(System.in);
   // num=sc.nextInt();
   //for(int i:votes)
     for(int i=0;i<votes.length;i++){
     votes[i]=sc.nextInt();
  }
 }
 void displayResult()
  {
  //for(int i:votes)
   for(int i=0;i < votes.length;i++)
     {
  System.out.println("the result " +votes[i]);
   }

 }
}

Why is System.out.println not giving any output?

2 Answers2