I really new to Java so I'm having some trouble figuring this out. So basically I have a text file that looks like this:
1:John:false
2:Bob:false
3:Audrey:false
How can I create an ArrayList from the text file for each line?
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2Do you even try anything before posting a query on stackoverflow?uncaught_exception– uncaught_exception2016-04-06 03:21:47 +00:00Commented Apr 6, 2016 at 3:21
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Thankyou all so much!!!!Audrey– Audrey2016-04-06 03:24:20 +00:00Commented Apr 6, 2016 at 3:24
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yea i do i have all my code if you wanna see itAudrey– Audrey2016-04-06 03:25:41 +00:00Commented Apr 6, 2016 at 3:25
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1I was asking to encourage you to look up tutorials, books and documentation before posting on stackoverflow. That is a better way to learn.uncaught_exception– uncaught_exception2016-04-06 03:29:41 +00:00Commented Apr 6, 2016 at 3:29
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5 Answers
Read from a file and add each line into arrayList. See the code for example.
public static void main(String[] args) {
ArrayList<String> arr = new ArrayList<String>();
try (BufferedReader br = new BufferedReader(new FileReader(<your_file_path>)))
{
String sCurrentLine;
while ((sCurrentLine = br.readLine()) != null) {
arr.add(sCurrentLine);
}
} catch (IOException e) {
e.printStackTrace();
}
}
2 Comments
Audrey
Thankyou so much! this helped I had to specify what type of array i needed other than that perfect thankyou!
Priyansh Goel
Ohh Yes. I missed it . Sorry. Can you please accept this answer? <Click on the tick to accept>
While the answer above me works, here's another way to do it. Make sure to import java.util.Scanner.
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<String>();
Scanner scan = new Scanner("YOURFILE.txt");
while(scan.hasNextLine()){
list.add(scan.nextLine());
}
scan.close();
}
Comments
If you know how to read a file line by line, either by using Scanner or by using BufferedReader then reading a text file into ArrayList is not difficult for you. All you need to do is read each line and store that into ArrayList, as shown in following example:
BufferedReader bufReader = new BufferedReader(new
FileReader("file.txt"));
ArrayList<String> listOfLines = new ArrayList<>);
String line = bufReader.readLine(); while (line != null)
{
listOfLines.add(line);
line = bufReader.readLine();
}
bufReader.close();
Just remember to close the BufferedReader once you are done to prevent resource leak, as you don't have try-with-resource statement
Comments
This will be help to you.
List<String> list = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new FileReader("list.txt"));
String line;
while ((line = reader.readLine()) != null) {
list.add(line);
}
reader.close();
Then you can access those elements in the arraylist.
Comments
java 8 lets you do this
String fileName = "c://lines.txt";
List<String> list = new ArrayList<>();
try (Stream<String> stream = Files.lines(Paths.get(fileName))) {
list = stream
.map(String::toUpperCase)
.collect(Collectors.toList());
} catch (IOException e) {
e.printStackTrace();
}
list.forEach(System.out::println);
