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?

Answer 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);
 }