ArrayOutOfIndex error when accessing value from splitted string?

Question

I am trying to split a string in the following format: AND 1 0.

The logic method below takes in a String read using .nextLine().

While I am able to split the String into Array using the split method and \\s+ regex, I run into an ArrayOutOfBound error whenever I try to access the second value of the array.

The second and third index of the Array should contain the values '1' and '2' respectively - why does this yield an error?

Code:

import java.util.*;

public class HelloWorld {

  public static int logic(String operator){
    String[] splitted = operator.split("\\s+");
    int val = 0;

    System.out.println(splitted.length); //Returns 3
    System.out.println(operator); //Returns AND 1 0
    System.out.println(splitted[0]); //Returns AND
    System.out.println(splitted[2]);  //ERROR
    return val;
  }

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int val = sc.nextInt(); //Error lies here, should be parsed as String.

        if(val == 1){
            int no_times = sc.nextInt();
            for(int i = 0 ; i < no_times; i++){
                System.out.println(logic(sc.nextLine()));
            }
            sc.close();
        }
    }
}

Input:

OR 1 1
AND 0 1
AND 1 0
OR 0 0
AND 0 0
OR 1 0
OR 0 1
OR 0 1
OR 1 1
OR 1 0

what is the output of `System.out.println("Length = %d",splitted.length)` ? — Vineet Bhat, Jan 18 '18 at 05:12
you can debug this issue. i think it's fine. check splitted's length. — Shen Yudong, Jan 18 '18 at 05:12
I've run the code. It gave the correct output. Maybe the string you are sending has a problem. — Sai Kishore, Jan 18 '18 at 05:17
The code is correct and should run without any error. Unless the space is anything other than ASCII space (0x20).. One of the possible values oxff. — Zaki Anwar Hamdani, Jan 18 '18 at 05:17
Is that _really all_ of the input? Your code seems to be expecting one line at the beginning containing `1` followed by the number of lines to be processed. Please [edit] your post and include the COMPLETE stack trace, formatted as `code`. — Jim Garrison, Jan 18 '18 at 06:13

score 1 · Answer 1 · answered Jan 18 '18 at 05:16

1

I have try running your code, and it produce the correct output without errors.

However when I try to replace the space between "AND", "1", "0" with some strange char(maybe in Chinese call "SBC case" space, those chars cannot be recognized by \\s+), it reproduce your error. So I advice you check whether there is a english space char(which can be recognized by \\s+) between "AND", "1", "0".

answered Jan 18 '18 at 05:16

firesurfing

145
3

That was my first suspicion, but the input file is correctly spaced. – Carrein Jan 18 '18 at 05:25

Upendra Shah · Answer 2 · 2018-01-18T06:07:11.357

Try this. you get that error because splitted's length is less than you want to print.

First Method

    public static int logic(String operator){
        String[] splitted = operator.split("\\s+");
        int val = 0;
        System.out.println(operator); //Prints "AND 1 0"
        System.out.println("splitted length :: "+splitted.length()); 
        for (String str:splitted) {
            System.out.println(str); //Prints "AND"
        }
        // System.out.println(splitted[1]); //ERROR
        return val;
    }

Second Method

    public static int logic(String operator){
        String[] splitted = operator.split("\\s+");
        int val = 0;
        System.out.println(operator); //Prints "AND 1 0"
        System.out.println("splitted length :: "+splitted.length()); 
        for (int i = 0; i<splitted.length();i++) {
            System.out.println(splitted[i]); //Prints "AND"
        }
        // System.out.println(splitted[1]); //ERROR
        return val;
    }

This works, but I would like to perform operations on the splitted string rather than just printing them out. — Carrein, Jan 18 '18 at 05:29
Check edited answer using second method you can perform operation which you want. — Upendra Shah, Jan 18 '18 at 06:02

score 0 · Answer 3 · answered Jan 18 '18 at 05:11

I am not able to see the error,the code snippet provided by you should work. Though you can use below to avoid exception:

public static int logic(String operator){
        String[] splitted = operator.split("\\s+");
        int val = 0;
        System.out.println(operator); //Prints "AND 1 0"
        for(String split : splitted) {
            System.out.println(split);
        }
        return val;
      }

score 0 · Answer 4 · answered Jan 18 '18 at 06:22

You really should make the intention of your code more clear, especially when asking for help. As for your problem, this is a duplicate of Scanner is skipping nextLine() after using next() or nextFoo()?

Scanner#nextInt doesn't consume the \n after the input, so the nextLine() is just receiving \n.

Fixed code:

public static void main(String[] args) {
    System.out.print("Type 1 to continue: ");
    Scanner sc = new Scanner(System.in);
    int val = sc.nextInt();

    if(val == 1){
        System.out.print("\nHow many tests do you want to run? ");
        int no_times = sc.nextInt();
        sc.nextLine();
        for(int i = 0 ; i < no_times; i++){
            System.out.print("\nLogic: ");
            System.out.println(logic(sc.nextLine()));
        }
        sc.close();
    }
}

score 0 · Answer 5 · answered Jan 18 '18 at 06:44

The nextLine method is reading the value from current cursor location to till the end of the line and it includes the delimiter as well. So when we read the first line of input it takes the space which is delimiter here. For example, if our first is like 1 1 OR 1 1

then first nextInt returns 1 then second nextInt return 1 then nextLine returns ' OR 1 1' and length of it is 4. I guess, your first input is wrong may be you are missing something there. one simple solution is just change the following line your code.

String[] splitted = operator.split("\\s+");

to

String[] splitted = operator.trim().split("\\s+");

Just trim before splitting. so that, trailing spaces are removed. It may solve your problem.

score -1 · Answer 6 · answered Jan 18 '18 at 05:36

-1

The full input takes in two integer first. This two integers were parsed by nextInt() rather than nextLine(), hence the given argument for the logic method was not taking in a complete String - hence the splitting fails.

answered Jan 18 '18 at 05:36

Carrein

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ArrayOutOfIndex error when accessing value from splitted string?

6 Answers6