File Reading Last Line

Question

I am having this code in Java to read from a file and pass the values to a vector but it seems not to consider the last line.

int lines = 0;
Vector<String> vc = new Vector<String>();
BufferedReader in = new BufferedReader(new FileReader(FILE_NAME));      
while(in.readLine() != null){
    if(lines >= 1){
        vc.addElement(in.readLine());       
    }

    lines++;
}

System.out.println(vc.size());

for(int i = 0; i< vc.size(); i++){          
    System.out.println(vc.get(i));
}

The elements of a file are

4
fdgdfs
sdfg
sdfg
sfdg
sdfg

for example and I want to read from the second line and add them in the vector. The results printing are

3
sdfg
sfdg
null

What seems to be the problem?

Eating code may be hazardous to health. Jokes apart, `lines>=1` is going to skip the first line since `lines` is initialized to 0. — Chetan Kinger, Apr 26 '15 at 12:28
You're calling in.readLine() twice per iteration. Call it once. Also, stop using Vector. It's obsolete for 15 years. And consider using http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#readAllLines%28java.nio.file.Path,%20java.nio.charset.Charset%29 — JB Nizet, Apr 26 '15 at 12:28
Also.. do you really need a `Vector` instead of `ArrayList`? — Maroun, Apr 26 '15 at 12:28
@MadConan I wouldn't say "*don't*", recall that `Vector`s are synchronized, sometimes you do want them. — Maroun, Apr 26 '15 at 12:32
Why `Vector` in 2015? Why `File` in 2015? Java 7+ has `Files.readAllLines()` — fge, Apr 26 '15 at 12:32
@MarounMaroun when you need a synchronized list, there is `Collections.synchronizedList()`. — JB Nizet, Apr 26 '15 at 12:33
@JBNizet Indeed, it's more efficient. I still hate to say "don't". — Maroun, Apr 26 '15 at 12:34
@MarounMaroun There really isn't any good reason to use `Vector` any more. Lots of good info out there. Here's a very popular one: http://stackoverflow.com/a/1386288/2919971 — MadConan, Apr 26 '15 at 13:17

Isuru Gunawardana · Answer 1 · 2015-04-26T12:36:21.653

2

Change:

while(in.readLine()!=null)

to:

 while((line = in.readLine())!=null)

Where line is a String you should define before the while loop.

Then use line variable as follows to add element,

vc.addElement(line);

As suggested in comments, you can use arraylist instead of vector, read this it explains why you should do it.

edited Apr 26 '15 at 12:36

answered Apr 26 '15 at 12:29

Isuru Gunawardana

2,847
6
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A.B. · Answer 2 · 2015-04-26T14:08:05.380

Use this code:

package stackoverflow;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;

public class FileReadingLastLine {

    private static final String FILE_NAME = "test";

    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<String>();
        try {
            BufferedReader in = new BufferedReader(new FileReader(FILE_NAME));
            String line = "";
            int lines = 0;
            while ((line = in.readLine()) != null) {
                if (lines >= 1) {
                    list.add(line);
                }
                lines++;
            }

            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        System.out.println("Size: " + list.size() + "\n");

        for (Iterator<String> iterator = list.iterator(); iterator.hasNext();) {
            String string = (String) iterator.next();
            System.out.println(string);
        }
    }
}

The output is:

Size: 5

fdgdfs
sdfg
sdfg
sfdg
sdfg

The content of the file named test is:

4
fdgdfs
sdfg
sdfg
sfdg
sdfg

File Reading Last Line

2 Answers2