Put .txt file data in array

Question

I'm new at java I would like to know how to read a .txt file and then put every single line in an array cell. .txt file must be formatted as shown:

car //goes in array[0]
boat //goes in array[1]
ship //goes in array[2]
airplane //goes in array[3]
//...and so on..

I've already tried to create a ReadFile class implemented in this way:

import java.io.*;
import java.util.*;
public class ReadFile {
    private Scanner x;

public void open(){
    try{
        x = new Scanner(new File("time_table_data.txt"));
    }catch(Exception e){
        System.out.println("Could Not Create The File");
    }
}

public String read(){
    String s = "";
    while(x.hasNext()){
        String a = x.next();
        s = a.format("%s\n",a);
    }
    return s;
}


public void close(){
    x.close();
}


}

What exact problem are you facing? You forgot to ask a question. Questions normally end with question marks. — Paul Samsotha
– Paul Samsotha, Commented Dec 28, 2013 at 11:13
Where is the code where you use this class and call its methods? — Paul Samsotha
– Paul Samsotha, Commented Dec 28, 2013 at 11:14
@peeskillet I think OP is asking for that class which is not here.. — AJ.
– AJ., Commented Dec 28, 2013 at 11:16
Also it would help to actually have an array in the class, since that is the requirement. Also make use of that array in your read method — Paul Samsotha
– Paul Samsotha, Commented Dec 28, 2013 at 11:16

Martijn Courteaux · Accepted Answer · 2013-12-28 11:18:07Z

2

The problem is that you don't know how many words there are coming. To solve that, you could use an ArrayList.

List<String> entries = new ArrayList<String>();
while (scanner.hasNext())
{
    entries.add(scanner.nextLine());
}
System.out.println(entries);

Access them using the get(int index) method:

String test = entries.get(0); // This will be "car"

answered Dec 28, 2013 at 11:18

Martijn Courteaux

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1 Comment

Thijser Over a year ago

And if you wish to convert it back to an array you can use entries.toArray();

keisar · Accepted Answer · 2013-12-28 11:24:30Z

2

if you're willing to use Apache Commons IO then you can do this really easy:

import org.apache.commons.io.FileUtils;

String[] linesArr = new String[0];
List<String> lines = FileUtils.readLines(new File("FILE_NAME.txt"));
if (lines != null) {
     linesArr = lines.toArray(linesArr);
}

answered Dec 28, 2013 at 11:24

keisar

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2 Comments

Giannis Over a year ago

Im a strong supporter of using libraries, although I am not sure if its good for total beginners. I would think that its better to first understand how you can do something, and from that point on use a library that will probably do it better than you.

keisar Over a year ago

@Giannis I agree, but I thought it should be here because it makes life much simpler after you learn the basics. If someone really wants to know the basics I would suggest writing it without even the java.util.Scanner class, i.e. read using FileInputStream, read the bytes and divide to lines, that would be the best learning exercise.

Tim B · Accepted Answer · 2013-12-28 11:18:32Z

1

Just do:

List<String> lines = new ArrayList<String>();

try (BufferedReader br = new BufferedReader(new FileReader(file))) {
    String line;
    while ((line = br.readLine()) != null) {
       lines.add(line); // Add line to list
    }
} // Try-with-resources closes reader

You don't need the scanner or anything else fancy when you just looking for whole lines.

If you really need an array not a list at the end you can just read out the array from the final List.

answered Dec 28, 2013 at 11:18

Tim B

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Comments

Rakesh KR · Accepted Answer · 2013-12-28 11:22:35Z

Make a method that reads all data from file and stores in a List as follows.

public ArrayList<String> fileRead(String fileName){
        File           f;
        String         s;
        FileReader     fr = null;
        BufferedReader br = null;
        ArrayList<String>   sl = new ArrayList<String>();
        try {
            f  = new File(fileName); 
            fr = new FileReader(f);
            br = new BufferedReader(fr);
            while((s=br.readLine())!=null){
                sl.add(s);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
                try {
                    if(br!=null)
                        br.close();
                    if(fr!=null)
                        fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }
        return sl;
}

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