java.lang.NumberFormatException: For input string: "100" while executing MapReduce

Question

I'm writing a MapReduce job for finding common friends on facebook.

This is the input for my mapper :

100, 200 300 400 500 600
200, 100 300 400
300, 100 200 400 500
400, 100 200 300
500, 100 300
600, 100

And this is part of my mapper code:

map{
        String line = value.toString();
        String[] LineSplits = line.split(",");


        String[] friends = LineSplits[1].trim().split(" ");
        for(int i =0; i<friends.length;i++) {
            int friend2 = Integer.parseInt(friends[i]);
            System.out.println(friend2);
        }

        int friend1 = Integer.parseInt(LineSplits[0]);
        System.out.println(friend1);
}

When I execute this,I am getting correct values in friend2. (Intege.parseInt is working fine here). The variable friend1 is supposed to get the value as '100'. But Integer.ParseInt is not working and I am getting an error like this:

java.lang.Exception: java.lang.NumberFormatException: For input string: "100"
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:354)
Caused by: java.lang.NumberFormatException: For input string: "100"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:580)
    at java.lang.Integer.parseInt(Integer.java:615)
    at com.hadoop.CFMapper.map(CFMapper.java:29)
    at com.hadoop.CFMapper.map(CFMapper.java:1)
    at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:430)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:366)
    at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:223)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

So I got stuck here. Why am I getting a NumberFormatException for this? and how can I rectify this?

That is weird. If there were any funny hidden characters like `\n` or `\r`, I would expect the error message to reflect that. Can you do a print of `LineSplits[0].length()` before you parse it? What does it give you? — sstan, Jun 16 '15 at 15:06
Try printing of the code that is causing an error. Logic says that when trying to parse "100" it should work - However there might be some hidden characters such as "100\n\r". You could always just String.replace them out of the string. — Sh4d0wsPlyr, Jun 16 '15 at 15:08
Ah! Now can you print out `(int)LineSplits[0].charAt(n)`, where `n` is 0, 1, 2 and 3. This way we can see what characters are hidden. You don't only have digits there. And tell us what you get for the 4 characters. — sstan, Jun 16 '15 at 15:11
@nafas I want that to be an int so that I could use it later in the map code. — MChirukuri, Jun 16 '15 at 15:11
@Mounika_22 yes , I understand, but you need to find out why its giving you an error first. just print the string as everyone else suggested, if you print the string out then u know if its an integer or not — nafas, Jun 16 '15 at 15:13
@nafas: printing the string won't be enough. the error message he gets already prints `"100"` as the string that it can't parse. But clearly, that string looks good. So we need to examine it character by character. — sstan, Jun 16 '15 at 15:14
@sstan how do you know if the string looks good? there could be many reason that the input file is not the same as the above. — nafas, Jun 16 '15 at 15:15
@Mounika_22 here is your problem mate, "65279" it looks like some sort of encoding, you should have recieved 49 48 48 as the output — nafas, Jun 16 '15 at 15:17
what if you simply `trim()` all Strings before parsing? `int friend2 = Integer.parseInt(friends[i].trim());` for example — Hovercraft Full Of Eels, Jun 16 '15 at 15:22
@Mounika_22 before I give any other suggestion, can you try `int friend1 = Integer.parseInt(LineSplits[0].tirm());` first — nafas, Jun 16 '15 at 15:22
@Mounika_22 try `int friend1 = new Scanner(LineSplits[0]).nextInt();` <-- generally not recommended. but if it works we know how to fix the issue — nafas, Jun 16 '15 at 15:26

score 7 · Accepted Answer · edited May 23 '17 at 12:06

7

Your file has an invalid Unicode Character 'ZERO WIDTH NO-BREAK SPACE' (U+FEFF). you need to get rid of that.

The character is not visible. So it's understandable that you didn't realize that it was there. You probably copy pasted in there by mistake. you'll have to see where you copied your data from.

I should mention that trimming your string in code won't work to get rid of that character. You really need to go in your input file and fix it from there.

You will find suggestions on how to get rid of the character in this thread.

Otherwise, if your file is not too big, why not start a fresh new file, and type in your values manually to be safe. :)

edited May 23 '17 at 12:06

Community

1
1

answered Jun 16 '15 at 15:18

sstan

35,425
6
48
66

there u see, the file is not always as it looks :) – nafas Jun 16 '15 at 15:19
I edited the input file. All I did was I backspaced the first line. So that invisible character was removed. Now everything works file. Thanks for the help. – MChirukuri Jun 16 '15 at 15:34

Ankur Anand · Answer 2 · 2015-06-16T15:31:37.880

0

Edit: As you mentioned in comment the length you are getting is 4

Maybe you can Trythis .

LineSplits[0].replace(u'\ufeff', '') and then try to parse and see what happens

If you look at the Integer.parseInt() jsl it says

Throws:

NumberFormatException - if the string does not contain a parsable integer.

So what if when the string: "100" reaches the ENDOFLINE . It can have character like \r\n or \n i.e line termination or null if the end of the stream has been reached, Which is clearly not "parsable integer". So you need to check for these before parsing.

edited Jun 16 '15 at 15:31

answered Jun 16 '15 at 15:00

Ankur Anand

3,873
2
23
44

You missed part of the code regarding the first split. he splits it on the coma first, then on the spaces for the second half. E.g. "100" and " 200 300 400 500 600". Then splits the second string on spaces. – Sh4d0wsPlyr Jun 16 '15 at 15:11

java.lang.NumberFormatException: For input string: "100" while executing MapReduce

2 Answers2