Read specific lines from a file in Java

Question

I am relatively new to Java programming and I have an assignment which I am finding difficult to understand. Its is basically an I/O program with string manipulation.

I have one input file, pb.txt, which looks like this;

01/23/16  -22  32- 34- 40- 69  PB 19  X4  01/13/16  -27  29- 34- 41- 44  PB  2  X3  
01/20/16  -5  39- 44- 47- 69  PB 24  X5  01/09/16  -12  31- 43- 44- 57  PB 11  X2  
01/16/16  -3  51- 52- 61- 64  PB  6  X2  01/06/16  -6  37- 39- 45- 55  PB 33  X3

Here is the Problem statement;

• Open the file pb.txt.
• Read the string lines.
• Extract the 5 winning numbers and the PB number
• Save them as integers n1, n2, n3, n4, n5, and pb.
• Assign an integer variable dateIndex for the date, which starts at 1 and is incremented by one for each date.

Output the data file pbo.txt will look as follows:

dateIndex  n1  n2  n3  n4  n5  pb

1   22  32  34  40  69  19

Note that spaces must separate the numbers.

I have done simple file I/O programs myself, but this one is tricky for me. I am unable to understand how I should separate the required lines from the file as there is other things written in the file as well, but I have to separate only the ones which are stated above. I appreciate any kind of help that I can get regarding this.

This is my first time posting on Stack Overflow so forgive me if I did something wrong.

Regards.

Answer 1

If the file is not too big, you can read all the lines as described in the accepted answer here.

If the file can be big, it would be better to use any other API to read a file line by line.

This first step shouldn't be so difficult.

On each line, you can then use a regular expression to find the necessary information.

The following link shows an example of a regular expression that matches your input: Regex

You cannot use it exactly as is, but it is a starting point.