A Good Method to read files in Java

Question

I Really would appreciate it if someone can help me with this. I am trying to do external sorting and I am stuck on the part of merging. I get how I should merge it just not sure what function to use.

Right now I am trying to read in the first words of multiple small text files and store them in a string array of the size of the amount of files. So basically I will have a string array of the first word of each file. Then I determine which one is the smallest alphabetically wise and write that to a new file, after that I would read the next word of the file of that smallest word. This word would be placed in the position of the smallest word that got outputted in string array and compare it to the rest of the first word from the other file. This will keep repeating till all words are sorted.

The main problem I am running into is the fact that I was using scanner and after the first run of comparing it cant switch the smallest word with the next word in the file because scanner don't keep a point of what it has read. I know readline do but since my files are all words separated by only a white space I can't use readline. Can someone please guide me to a sufficient reading function that can't help me solve this problem.

  for (int i = 0; i<B;i++)
  {
  try
  {
    BufferedReader ins = new BufferedReader(new FileReader(Run-"+ i + ".txt"));
    Scanner scanner2 = new Scanner(ins);
    temp3[i] = scanner2.next();

                System.out.println(temp3[i]);
            }
            catch(IOException e)
            {   
            }
        }
        for(int i=0;i<N;i++)
        {
            String smallest = temp3[0];
            int smallestfile = 0;
            for(j=0;j<B;j++)
            {
                int comparisonResult = smallest.compareTo(temp3[j]);
                if(comparisonResult>0)
                {
                smallest = temp3[j];
                smallestfile = j;
                }
            }
            BufferedReader ins = new BufferedReader(new FileReader("C:/Run-"+ smallestfile + ".txt"));
            Scanner scanner2 = new Scanner(ins);
            if(scanner2.hasNext())
            {
                temp3[smallestfile]=scanner2.next();
            }
        }
}
catch(Exception e)
{
}

Answer 1

If the files are small enough read the entire file to memory, and use String.split() to separate the strings in arrays and do your magic.

If the the files are bigger, keep then open and read each byte until you find and space, then do it for all the files, compare the strings, do your magic and repeat until all the files reach the end.

EDIT :

• how to read the files with BufferedReader
• how to split the lines with String.split()

String line = readeOneLineFromTheCurrentFile(); String[] words = line.split(" ");