Store text file content line by line into array

Question

all,I'm now facing the problem of no idea on storing the content in text file into the array. The situation is like, text file content:

abc1
xyz2
rxy3

I wish to store them into array line by line, is that possible? What I expect is like this:

arr[0] = abc1
arr[1] = xyz2
arr[2] = rxy3

I've try something like this, but seem like not work for me. If anyone can help me, really thanks a lot.

The code is:

BufferedReader in = new BufferedReader(new FileReader("path/of/text"));
        String str;

        while((str = in.readLine()) != null){
            String[] arr = str.split(" ");
            for(int i=0 ; i<str.length() ; i++){
                arr[i] = in.readLine();
            }
        }

*"but seem like not work for me"* What error or exception resulted? Copy/paste it to the forum as an [edit to the question](http://stackoverflow.com/posts/16100175/edit). — Andrew Thompson, Apr 19 '13 at 08:15
If you want the entire line in each array element, why are you splitting it? — NilsH, Apr 19 '13 at 08:15
i thought the split(" ") can help me differentiate the next line? so that it can become lien 1,2,3.. — salemkhoo, Apr 19 '13 at 08:17
@salemkhoo `in.readLine()` has already read the line for you. — NilsH, Apr 19 '13 at 08:19

score 25 · Accepted Answer · edited Nov 10 '16 at 03:20

25

I would recommend using an ArrayList, which handles dynamic sizing, whereas an array will require a defined size up front, which you may not know. You can always turn the list back into an array.

BufferedReader in = new BufferedReader(new FileReader("path/of/text"));
String str;

List<String> list = new ArrayList<String>();
while((str = in.readLine()) != null){
    list.add(str);
}

String[] stringArr = list.toArray(new String[0]);

edited Nov 10 '16 at 03:20

dimid

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answered Apr 19 '13 at 08:16

Kevin Bowersox

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Thanks for your guidance, Kevin, you really help me a lots, thanks! – salemkhoo Apr 19 '13 at 08:25
hi Kevin, thanks for your answer, my doubt is how I can print the stringArr when I tried to print the stringArr i am getting some output like [Ljava.lang.String;@17bd8e. Can anyone suggest me what is the correct way to print the contents of stringArr. – Chinmoy Jun 10 '16 at 11:49
Use Arrays.toString(stringArr) to print the content of array. – Praveen Kishor Jul 08 '19 at 09:27

Evgeniy Dorofeev · Answer 2 · 2013-04-19T08:31:30.733

13

The simplest solution:

List<String> list = Files.readAllLines(Paths.get("path/of/text"), StandardCharsets.UTF_8);
String[] a = list.toArray(new String[list.size()]);

Note that java.nio.file.Files is since 1.7

edited Apr 19 '13 at 08:31

answered Apr 19 '13 at 08:21

Evgeniy Dorofeev

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score 3 · Answer 3 · edited Nov 04 '14 at 05:37

3

This should work because it uses List as you don't know how many lines will be there in the file and also they may change later.

BufferedReader in = new BufferedReader(new FileReader("path/of/text"));
String str=null;
ArrayList<String> lines = new ArrayList<String>();
while((str = in.readLine()) != null){
    lines.add(str);
}
String[] linesArray = lines.toArray(new String[lines.size()]);

edited Nov 04 '14 at 05:37

dotnetom

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answered Apr 19 '13 at 08:20

IndoKnight

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hi Guys, thanks for the answer, my doubt is how I can print the linesArray when I tried to print the linesArray i am getting some output like [Ljava.lang.String;@d8dc5a. Can anyone suggest me what is the correct way to print the contents of linesArray. – Chinmoy Jun 10 '16 at 10:39

score 3 · Answer 4 · edited Jun 20 '20 at 09:12

3

JAVA 8 :

Files.lines(new File("/home/abdennour/path/to/file.txt").toPath()).collect(Collectors.toList());

edited Jun 20 '20 at 09:12

Community

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answered Jun 11 '15 at 07:18

Abdennour TOUMI

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Rahul · Answer 5 · 2013-04-19T08:29:37.443

2

You need to do something like this for your case:-

int i = 0;
while((str = in.readLine()) != null){
    arr[i] = str;
    i++;
}

But note that the arr should be declared properly, according to the number of entries in your file.

Suggestion:- Use a List instead(Look at @Kevin Bowersox post for that)

edited Apr 19 '13 at 08:29

answered Apr 19 '13 at 08:17

Rahul

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score 2 · Answer 6 · answered Apr 19 '13 at 08:20

2

Just use Apache Commons IO

List<String> lines = IOUtils.readLines(new FileInputStream("path/of/text"));

answered Apr 19 '13 at 08:20

Zutty

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Achintya Jha · Answer 7 · 2013-04-19T08:28:48.907

1

Try this:

String[] arr = new String[3];// if size is fixed otherwise use ArrayList.
int i=0;
while((str = in.readLine()) != null)          
    arr[i++] = str;

System.out.println(Arrays.toString(arr));

edited Apr 19 '13 at 08:28

answered Apr 19 '13 at 08:16

Achintya Jha

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score 1 · Answer 8 · answered Apr 19 '13 at 08:17

When you do str = in.readLine()) != null you read one line into str variable and if it's not null execute the while block. You do not need to read the line one more time in arr[i] = in.readLine();. Also use lists instead of arrays when you do not know the exact size of the input file (number of lines).

BufferedReader in = new BufferedReader(new FileReader("path/of/text"));
String str;

List<String> output = new LinkedList<String>();

while((str = in.readLine()) != null){
    output.add(str);
}

String[] arr = output.toArray(new String[output.size()]);

score 1 · Answer 9 · answered Nov 23 '16 at 09:16

You can use this full code for your problem. For more details you can check it on appucoder.com

class FileDemoTwo{
    public static void main(String args[])throws Exception{
        FileDemoTwo ob = new FileDemoTwo();
        BufferedReader in = new BufferedReader(new FileReader("read.txt"));
        String str;
        List<String> list = new ArrayList<String>();
        while((str =in.readLine()) != null ){
            list.add(str);
        }
        String[] stringArr = list.toArray(new String[0]);
        System.out.println(" "+Arrays.toString(stringArr)); 
    }

}

score 0 · Answer 10 · answered Apr 19 '13 at 12:29

0

Suggest use Apache IOUtils.readLines for this. See link below.

http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/IOUtils.html

answered Apr 19 '13 at 12:29

yogiam

168
7

score 0 · Answer 11 · answered Jul 26 '20 at 11:26

0

You can use this code. This works very fast!

public String[] loadFileToArray(String fileName) throws IOException {
    String s = new String(Files.readAllBytes(Paths.get(fileName)));
    return Arrays.stream(s.split("\n")).toArray(String[]::new);
}

answered Jul 26 '20 at 11:26

Mirzoxid Ulugmurodov

46
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score 0 · Answer 12 · answered Oct 24 '22 at 20:40

0

String a =  "John\n" +
            "Michael Kai\n" +
            "Susan Elrond";
    String[] b = a.split(System.getProperty("line.separator"));
    System.out.println(Arrays.toString(b));

answered Oct 24 '22 at 20:40

oskan001

11
1

Store text file content line by line into array

12 Answers12

JAVA 8 :

Linked