Question

Possible Duplicate:
How do I compare strings in Java?

Consider the following 2D array of Strings a[5][5],

I store three values in the first three blocks in the array “a”.
When I print my array, I get the following output.

ABC

null

DEF

null

These values are present in a file and I retrieve the values and store them in an array of strings.

The file (“file.txt”)looks like this,

A B C

D E F

Here is my code,

Declaration:

static String [][] a= new String [4][4];
public static String newline = System.getProperty("line.separator");
private static int i,j;

Main code:

i=j=0;
        FileInputStream fin;
        fin = new FileInputStream("file.txt");
        DataInputStream in = new DataInputStream (fin);
        BufferedReader br = new BufferedReader (new InputStreamReader (in));
        while((c = (char)br.read()) != (char)-1)
        {
            if (c != '  ' && c != (char)'\n')
            {
                a[i][j] = Character.toString(c);
                j++;
            }
            else if (c == '\n')
            {
                i++;
                j = 0;
            }
        }
        for (int i=0;i<5;i++)
        {
            for (int j=0;j<5;j++)
            {
                if (newline.equals(a[i][j]))
                {
                    mainArray[i][j] = null;
                }
            }
        }

Here is how I print my array,

        for (int i=0;i<5;i++)
        {
            for (int j=0;j<5;j++)
            {
                System.out.print(a[i][j]);
            }
           System.out.println("");
        }

My desired output should be,

ABCnullnull

DEFnullnull

Is there a better way to work on this problem??

Answer 1

BufferedReader has a readLine() method that will return a string with all the chars preceding the \n or \r. It also returns null at the end of the stream.

FileInputStream fin;
fin = new FileInputStream("file.txt");
DataInputStream in = new DataInputStream (fin);
BufferedReader br = new BufferedReader (new InputStreamReader (in));
List<String> list = new ArrayList<String>();
String line;
while ((line= br.readLine())!=null)
{
  list.add(line);  
}

This will cope with any number of returns and arbitrary length strings.

Or if you must have each line as and array

        FileInputStream fin;
        fin = new FileInputStream("file.txt");
        DataInputStream in = new DataInputStream(fin);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        List<char[]> list = new ArrayList<char[]>();
        String line;
        while ((line = br.readLine()) != null) {
            if(!line.isEmpty()) list.add(line.toCharArray());
        }

Reading your file should result in a List size of two each containing and array of 5 chars. [‘A’,’ ‘,’B’,’ ‘,’C’] then [‘D’,’ ‘,’E’,’ ‘,’F’]