Java Array parsing

Question

I have read a file into an array but am wondering how to parse certain values from that array.

My code:

        ...
        try{
             ...
             String strLine;
             String delims= "[ ]+";
             //parsing it
             ArrayList parsedit = new ArrayList();
             while((strLine=br.readLine())!=null){
                 System.out.println("Being read:");
                 System.out.println(strLine);
                 parsedit.add(strLine.split(delims));
             }
             System.out.println("Length:" + parsedit.size());
             in.close();   
             ...

The files that I am reading in are like this:

a b c d e f g
1 2 3 4 5 6 7
1 4 5 6 3 5 7
1 4 6 7 3 2 5

Which makes the output like this:

How many files will be input? 1
Hey, please write the full path of the input file number1! 
/home/User/Da/HA/file.doc
Being read:
a b c d e f g 
Being read:
1 2 3 4 5 6 7 
...
Length:4

I would like to parse out this data and just have the first and fifth values remaining, so that it would read like this instead:

a e
1 5

Does anyone have a recommendation on how to go about it? EDIT: Following some of the suggestions I have changed my code to:

public static void main(String[] args) {
        System.out.print("How many files will be input? ");
        Scanner readIn=new Scanner(System.in);
        int input=readIn.nextInt();
        int i=1;
        while(i<=input){
            System.out.println("Hey, please write the full path of the input file number" + i + "! ");
            Scanner fIn=new Scanner(System.in);
            String fileinput=fIn.nextLine();
          try{
             FileInputStream fstream=new FileInputStream(fileinput);
             DataInputStream in=new DataInputStream(fstream);
             BufferedReader br=new BufferedReader(new InputStreamReader(in));
             String strLine;
             String delims= "[ ]+";
             ArrayList parsedit = new ArrayList();
             while((strLine=br.readLine())!=null){
                 System.out.println("Being read:");
                 System.out.println(strLine);
                 parsedit.add(strLine.split(delims));
             }
             String[] splits=strLine.split(delims);
             System.out.println("Length:" + splits.length);
             in.close();   
        }
        catch(Exception e){
            System.err.println("Error: " + e.getMessage());
        }
        i++;
    }
  }
}

This doesn't give back any errors but it doesn't seem to be working all the same. Am I missing something silly? The output is this:

How many files will be input? 1
Hey, please write the full path of the input file number1! 
/home/User/Da/HA/file.doc
Being read:
a b c d e f g 
Being read:
1 2 3 4 5 6 7 
...

But despite the fact that I have a line to tell me the array length, it never gets printed, which tells me I just ended up breaking more than I fixed. Do you know what it is that I may be missing/forgetting?

Instead of BufferedReader.readLine() you could try using BufferedReader.read() to read character by character to find what you're looking for. — Shaded
– Shaded, Commented Aug 23, 2012 at 14:51
Please don't use DataInputStream to read text vanillajava.blogspot.co.uk/2012/08/… Its more confusing than useful. — Peter Lawrey
– Peter Lawrey, Commented Aug 23, 2012 at 14:52
Remove it, you don't need it. For a better alternative use FileReader as suggested in the article. — Peter Lawrey
– Peter Lawrey, Commented Aug 23, 2012 at 16:04

Razvan · Accepted Answer · 2012-08-23 16:07:28Z

1

The split() function returns an array of strings representing the tokens obtained from the original String.

So, what you want is to keep only the first and the 5th token (splits[0] & splits[4]):

  String[] splits = strLine.split(delims); 
  //use the splits[0] & splits[4] to create the Strings you want

Regarding your update, replace this:

 while((strLine=br.readLine())!=null){
             System.out.println("Being read:");
             System.out.println(strLine);
             parsedit.add(strLine.split(delims));
 }

With this:

 while((strLine=br.readLine())!=null){
             System.out.println("Being read:");
             String splits[] = strLine.split(delims);
             System.out.println(splits[0]+" "+splits[4]);
             parsedit.add(splits);
 }

edited Aug 23, 2012 at 16:07

answered Aug 23, 2012 at 14:51

Razvan

10.2k6 gold badges41 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Keppil Over a year ago

I changed your splits[5] to splits[4], and apparently destroyed your concurrent edit. Sorry.

Stephopolis Over a year ago

This would go after the "parsedit.add(strLine.split(delims));" line?

Razvan Over a year ago

It depends on your requirements. splits = strLine.splits(delims) returns the array of strings. => splits = {a,b,c,d,e...} , for the next line splits = {1,2,3,4...} and so on

Stephopolis Over a year ago

I am horribly sorry, but I am not sure I understand. Do you mind if I update my question so I can get further help?

Stephopolis Over a year ago

The question has been updated. If you et a chance to have another look I would be more than grateful. Thanks so much!

Anurag Ramdasan · Accepted Answer · 2012-08-23 14:51:37Z

0

You can try this

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

This way all your elements will be stored in a sequence in the array line. This will allow you to access whatever element you want.

answered Aug 23, 2012 at 14:51

Anurag Ramdasan

4,3305 gold badges34 silver badges53 bronze badges

2 Comments

Stephopolis Over a year ago

Are you suggesting doing this instead of: parsedit.add(strLine.split(delims)); ?

Anurag Ramdasan Over a year ago

what i am suggesting is to read the entire page into the String s. and then split the characters of string into an array.

nhahtdh · Accepted Answer · 2012-08-23 14:52:36Z

0

You just need to get the first and the fifth value out of the String[] returned by strLine.split(delims).

(I am assuming you know what you are doing in your current code. You are assuming that each line will contains the same number of "columns", delimited by at least 1 space character. It is a fair assumption, regardless.)

answered Aug 23, 2012 at 14:52

nhahtdh

56.9k15 gold badges131 silver badges164 bronze badges

2 Comments

Stephopolis Over a year ago

But how do you recommend going about getting the first and the fifth value?

nhahtdh Over a year ago

@User: The split() function returns an array, which you can get the 1st and 5th value @ index 0 and 4.

Collectives™ on Stack Overflow

Java Array parsing

3 Answers 3

5 Comments

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

5 Comments

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related