What is wrong with my bash script that uses my java code?

Question

I am writing a simple java and bash program, but it is not working. Let me know where is wrong.

Bash:

    for i in [1..100]; do 
         echo $i
         java prob2 $i 
    done

Java:

import java.io.*;

public class prob2
{
    public static void main( String[] args )
    {
            int l = args.length;
            if ( l == 1 )
            {
                    int num = Integer.parseInt(args[0]);
                    while ( num != 0 && num != 1)
                            num = num - 2;
                    if ( num == 0 )
                            System.out.println("Even");
                    else if ( num == 1 )
                            System.out.println("Odd");
            }
    }
}

The error I'm getting is:

Exception in thread "main" java.lang.NumberFormatException: For input string: "[1..100]" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) at java.lang.Integer.parseInt(Integer.java:492) at java.lang.Integer.parseInt(Integer.java:527) at prob2.main(prob2.java:10)

Exception in thread "main" java.lang.NumberFormatException: For input string: "[1..100]" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) at java.lang.Integer.parseInt(Integer.java:492) at java.lang.Integer.parseInt(Integer.java:527) at prob2.main(prob2.java:10) — user1559897
– user1559897, Commented Nov 10, 2012 at 20:44
The exception shows that bash doesnt interpret [1..100] as a sequence but passes it as only value in the list, try for i in $(seq 1 10);. — rsp
– rsp, Commented Nov 10, 2012 at 20:46
I removed the Java tag because there is no Java in this problem. — Marko Topolnik
– Marko Topolnik, Commented Nov 10, 2012 at 20:47
Not related to your problem, but you need to look up how to use the modulo operator. — Frank Pavageau
– Frank Pavageau, Commented Nov 10, 2012 at 20:48

Reese Moore · Accepted Answer · 2012-11-10 20:45:36Z

4

That's not how you would do a bash loop. Try this:

for i in `seq 1 100`; do 
     echo $i
     java prob2 $i 
done

As an aside, a faster algorithm for determining if a number is odd or even is to take it modulo 2:

if (num % 2 == 0) {
    System.out.println("Even");
} else {
    System.out.println("Odd");
}

answered Nov 10, 2012 at 20:45

Reese Moore

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2 Comments

user1559897 Over a year ago

so my algorithm is O(n)...what is modulo?

Reese Moore Over a year ago

"In computing, the modulo operation finds the remainder of division of one number by another." - en.wikipedia.org/wiki/Modulo_operation

P.P · Accepted Answer · 2012-11-10 20:47:26Z

4

You have to use curly braces, not array brackets:

 for i in {1..100}; do 
         echo $i
         java prob2 $i 
    done

answered Nov 10, 2012 at 20:47

P.P

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