Not asking for second input

Question

Code:

public class Adddemo {

    public static void main(String[] args) throws IOException {
        int i, j, k;
        System.out.println("enter value of i: ");
        i = (int) System.in.read();
        System.out.println("enter value of j: ");
        j = (int) System.in.read();

        k = i + 1;

        System.out.println("sum is: " + k);
    }
}

Is System.in.read used for multiple inputs?

What do you mean? Your question is code-only. What is the behavior you expect, and what does it do instead? — RealSkeptic, Jun 11 '15 at 12:47
output: enter value of i: 5 enter value of j: /*it does not wait for my input for j*/ sum is: 54 — Max410, Jun 11 '15 at 12:52
This is an explanation also: http://stackoverflow.com/questions/15446689/what-is-the-use-of-system-in-read-in-java — Surely, Jun 11 '15 at 12:56
@psychocoder if your problem is it doesn't ask 2nd value then try adding `System.in.read()` before statement `j=System.in.read();` — Madhawa Priyashantha, Jun 11 '15 at 12:57
Similar problem with `read` in `BufferedReader`: http://stackoverflow.com/questions/30687153/use-int-as-input-for-gregoriancalendar-but-am-not-able-to-continue-scanning-java — Pshemo, Jun 11 '15 at 13:10

Uma Kanth · Answer 1 · 2015-06-11T13:02:29.750

3

System.in.read() is used to read a character.

suppose you enter 12, then i becomes 1(49 ASCII) and j becomes 2(50 ASCII).

suppose you enter 1 and then press enter, i becomes (ASCII 49) and enter(ASCII 10), even enter is considered a character and hence skipping your second input.

use a scanner or bufferedReader instead.

Using a scanner

Scanner sc = new Scanner(System.in);
int i = sc.nextInt();
int j = sc.nextInt();
int k = i + j; 
System.out.println(k);

Using a BufferedReader

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int i = Integer.parseInt(reader.readLine());
int j = Integer.parseInt(reader.readLine());
int k = i + j;
System.out.println(k);

edited Jun 11 '15 at 13:02

answered Jun 11 '15 at 12:53

Uma Kanth

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If u print only value of j than it displays 10. and also it doesn't even ask for the input of j... thats confusing to me.. – Max410 Jun 11 '15 at 13:01
because 10 is the ASCII value of new line. Please check the [ASCII Table](http://www.asciitable.com/). – Uma Kanth Jun 11 '15 at 13:02
David and Pshemo did the right search, they gave you the right question [here](http://stackoverflow.com/questions/30687153/use-int-as-input-for-gregoriancalendar-but-am-not-able-to-continue-scanning-java). – Uma Kanth Jun 11 '15 at 13:05
@psychocoder you cannot read integer values using `System.in.read()`, you will need some extra help(`Scanner` or `BufferedReader`). Every character is considered an input using `System.in.read()`. – Uma Kanth Jun 11 '15 at 13:14
Yeah. I got it. Thank you. and I will use Scanner instead. – Max410 Jun 11 '15 at 13:15

score 1 · Answer 2 · answered Jun 11 '15 at 13:38

System.in.read() doesn't read a number, it reads one byte and returns its value as an int.

If you enter a digit, you get back 48 + that digit because the digits 0 through 9 have the values 48 through 57 in the ASCII encoding.

To read a number from System.in you should use a Scanner.

nafas · Answer 3 · 2015-06-11T12:53:42.573

0

use Scanner class instead:

 import java.util.Scanner;
 public class Adddemo {

    public static void main(String[] args) throws IOException {
        Scanner read=new Scanner(System.in);
        int i,j,k;
        System.out.println("enter value of i: ");
        i=(int)read.nextInt();
        System.out.println("enter value of j: ");
        j=(int)read.nextInt();

        k=i+1;

        System.out.println("sum is: "+k);
    }    
 }

edited Jun 11 '15 at 12:53

answered Jun 11 '15 at 12:50

nafas

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Yeah, `InputStream.read()` only reads a single byte at a time. If your console is using a multi-byte character encoding (such as UTF-16) then it won't work. – Phylogenesis Jun 11 '15 at 12:52
I want to read the second value. It doesn't even ask for that. And i know Scanner class. I have to use System.in.read(). – Max410 Jun 11 '15 at 13:03
@psychocoder `System.in.read()` reads only a single byte. It sounds like you're pressing enter after typing the first number (you shouldn't). – Phylogenesis Jun 11 '15 at 13:08
Yeah. I got it. Thank you. – Max410 Jun 11 '15 at 13:16

score 0 · Answer 4 · answered Jun 11 '15 at 13:20

System.in.read() reads 1 byte at a time.

if you want to feed your input values for i and j , do this
Leave one space between 1 and 2 while giving input in console
1 will be taken as value for i
2 will be taken as value for j

giving input as 12 (no spaces) will also yield the same result, cuz each byte is considered as an input

program
    int i,j;
        char c,d;
        System.out.println("enter value of i: ");
        i=(int)System.in.read();
        System.out.println("enter value of j: ");
        j=(int)System.in.read();

        System.out.println("i is: "+i);
        System.out.println("j is: "+j);

Output:
enter value of i,j: 
1 2          //leave one space 

i is: 1
j is: 2

let me know if you didn't understand yet

commonly we use System.in.read() to read one byte at a time during file read scenarios — divine, Jun 11 '15 at 13:26

Not asking for second input

4 Answers4

Using a scanner

Using a BufferedReader

Linked