Member Avatar for Onlineshade

How to take input in a array in Java? my code is....

String[] array=null;
		Scanner sc = new Scanner(System.in);
                System.out.println("How many Numbers:");
                String r = sc.nextLine();
                Scanner sc1 = new Scanner(System.in);
		System.out.println("Enter Number:");
		for (int m = 0; m < r.length(); m++)
                    array=sc1.next();

I cant do this.
Please help.

  • 5 Contributors
  • 6 Replies
  • 133 Views
  • 1 Day Discussion Span
  • Latest Post Latest Post by Ezzaral

Dani AI

Generated

's original snippet failed for two linked reasons: the array variable was never initialized and the "how many" answer was read as a String and then iterated with r.length() (which counts characters, not number items). and pointed to the core fixes — allocate the container and use a numeric type for numeric input — and showed a working example that prints the result.

A few practical tips not yet covered in the thread:

  • Use a single Scanner on System.in. Creating multiple Scanners can make input behave oddly and closing one can close the underlying stream.
  • Beware mixing nextInt() and nextLine(); a leftover newline can be consumed unexpectedly. Consume the rest of the line explicitly when switching modes.
  • Validate input and catch NumberFormatException/InputMismatchException to handle bad tokens gracefully.
  • If the number of inputs is unknown or dynamic, prefer ArrayList<Integer> (resizable) over a fixed array.

A simple alternative pattern: read one line of space-separated numbers, split it, parse tokens, and collect them into a list or an int array. This avoids count parsing and many common Scanner pitfalls.

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

try (Scanner sc = new Scanner(System.in)) {
    String line = sc.nextLine().trim();       // read all numbers on one line
    String[] tokens = line.split("\\s+");
    List<Integer> nums = new ArrayList<>();
    for (String t : tokens) {
        try { nums.add(Integer.parseInt(t)); } catch (NumberFormatException ex) { /* skip or log */ }
    }
    int[] arr = nums.stream().mapToInt(Integer::intValue).toArray();
    System.out.println(java.util.Arrays.toString(arr));
}

Note: try-with-resources requires Java 7+. Also check for negative sizes or other edge cases if a count-based approach is used.

Recommended Answers

All 6 Replies

Member Avatar for Onlineshade

I can do it in c++, like....

cout<<"How many numbers?";
cin>>n;
for(int i=0;i<n;i++)
cin>>array[i];

But how to do this in Java?

Member Avatar for NormR1

Your code does not give a real value to the array variable: array
You need to use the new statement to give it a value:
array = new String[2000]; // create an array with 2000 slots

After creating the array, you need to assign values to each of its slots:
array = new String(); // put a String object into the array
or
array = "an item";
or
array = <refToObject>.methodThatReturnsString();

Edited by NormR1 because: n/a
Member Avatar for Rameshwar Soni

You want to enter numbers in an array then why are you declaring an String array. Go for an integer array. You can do it this way

int[] num;  // declaring an integer array
Scanner s=new Scanner(System.in);
System.out.println("How many numbers ?");
int how_many=s.nextInt();
num=new int[how_many]; // creating the array of the specified size
for(int i=0;i<num.length;i++)
{
   num[i]=s.nextInt();
}

Please import the Scanner class.........i.e. import java.util.Scanner; at the top of the code

Edited by Rameshwar Soni because: n/a
Member Avatar for Onlineshade

Thanks. I will try it.

Member Avatar for sameerRKO

i have just done it,hope it helps

import java.util.Arrays;
import java.util.Scanner;


public class ArraySum {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("Enter size of the array : ");
		Scanner sc=new Scanner(System.in);//scanner for size of array
		int n = sc.nextInt();
		int[] arrayA = new int[n];
		
		
		Scanner sa=new Scanner(System.in);//scanner for array A
		
		
		System.out.println("Enter num for array A: ");
		for (int i=0;i<n;i++){
			arrayA[i]=sa.nextInt();
		}
		System.out.println("arrayA: "+Arrays.toString(arrayA));
		

	}

}
Edited by Ezzaral because: Fixed code tag.
Member Avatar for Ezzaral

@sameer: Do not simply post solutions to peoples' homework assignments. That is not the point of these forums. We are here to help people learn - not do the work for them.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.