Fastest way to read a file line by line with 2 set

问题:

What is the fastest way I can read line by line with each line containing two Strings. An example input file would be:

Fastest, Way
To, Read
One, File
Line, By Line
.... can be a large file

There are always two sets of strings on each line that I need even if there are spaces between the String e.g. "By Line"

Currently I am using

FileReader a = new FileReader(file);
            BufferedReader br = new BufferedReader(a);
            String line;
            line = br.readLine();

            long b = System.currentTimeMillis();
            while(line != null){

Is that efficient enough or is there a more efficient way using standard JAVA API (no outside libraries please) Any help is appreciated Thanks!

回答1:

It depends what do you mean when you say "efficient." From the point of view of performance it is OK. If you are asking about the code style and size, I pesonally do almost you do with a small correction:

        BufferedReader br = new BufferedReader(new FileReader(file));
        String line;
        while((line = br.readLine()) != null) {
             // do something with line.
        }

For reading from STDIN Java 6 offers you yet another way. Use class Console and its methods

readLine() and readLine(fmt, Object... args)

回答2:

import java.util.*;
import java.io.*;
public class Netik {
    /* File text is
     * this, is
     * a, test,
     * of, the
     * scanner, I
     * wrote, for
     * Netik, on
     * Stack, Overflow
     */
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(new File("test.txt"));
        sc.useDelimiter("(\\s|,)"); // this means whitespace or comma
        while(sc.hasNext()) {
            String next = sc.next();
            if(next.length() > 0)
                System.out.println(next);
        }
    }
}

The result:

C:\Documents and Settings\glowcoder\My Documents>java Netik
this
is
a
test
of
the
scanner
I
wrote
for
Netik
on
Stack
Overflow

C:\Documents and Settings\glowcoder\My Documents>

回答3:

If you want separate two sets of String you can do this in that way:

BufferedReader in = new BufferedReader(new FileReader(file));
String str;
while ((str = in.readLine()) != null) {
    String[] strArr = str.split(",");
    System.out.println(strArr[0] + " " + strArr[1]);
}
in.close();