CODEWITHSUNDEEP
java
Runeony1
Runeony1

Reputation: 229

Read a file and convert it to an array (Java)

So I have a collection of phrases that are separated by newlines and I would like to populate an array with these phrases. This is what I have so far:

   Scanner s;
   s = new Scanner(new BufferedReader(new FileReader("Phrases.txt")));
   for(i = 0; i < array.length;i++)
   {
   s.nextLine() = array[i];
   }

Is there a fast and simple way to just populate an array with phrases separated by newlines?

Upvotes: 3

Views: 4218

Answers (6)

durron597
durron597

Reputation: 32343

Don't waste your time with Scanner. BufferedReader is just fine. Try this:

BufferedReader br = new BufferedReader(new FileReader("Phrases.txt")));
LinkedList<String> phrases = new LinkedList<String>();
while(br.ready()) {
    phrases.add(br.readLine());
}
String[] phraseArray = phrases.toArray(new String[0]);

By the way it's important to use LinkedList not ArrayList if the file is large. That way you only create one array at the end. Otherwise you will have a lot of large array creation and wasted memory.

Upvotes: 1

amit
amit

Reputation: 178521

It can be done with a 1 liner with apache commons and specifically FileUtils.readLines()

FileUtils.readLines(myFile).toArray(new String[0]);

Upvotes: 1

jma127
jma127

Reputation: 1432

You have the assignment operation inverted (array[i] should be set to s.nextLine(), not the other way around. Also, it would be best to modify the for loop to terminate when no more lines exist:

for(i = 0; i < array.length && s.hasNextLine() ;i++) {
     array[i] = s.nextLine()
}

Upvotes: 1

Brian Agnew
Brian Agnew

Reputation: 272417

Since you don't know how many phrases you're likely to have (I suspect), I would populate an ArrayList<String> and convert it to an array using ArrayList.toArray() once you're done. I'd perhaps keep it as a Java collection, however, for greater flexibility.

Upvotes: 1

Rohit Jain
Rohit Jain

Reputation: 213391

The assignment should be reverse: -

array[i] = s.nextLine();

And, I think you should fill your array based on the input received from the file. Here you are receving input based on the length of your pre-declared array. I mean, since you are using an array, your size is fixed. So you can only populate it with a fixed number of phrases.

A better way would be to use an ArrayList.

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

Now, you can populate your arraylist, based on the phrases you get from your file. You don't need to pre-define the size. It increases in size dynamically.

And to add phrases, you would do: -

phrases.add(s.nextLine());

With a while loop to read till EOF.

while (s.hasNextLine()) {
    phrases.add(s.nextLine());
}

Upvotes: 4

PermGenError
PermGenError

Reputation: 46428

you are doing it wrong. it has to be 

for(i = 0; i < array.length;i++)
   {
   array[i]=s.nextLine();
   }

array[i] = value; // the value would be assigned into the array at index i.

However, a better option would be to use a List implementing classes such as ArrayList which gives you an advantage of dynamic size.

 List<String> list = new ArrayList<>();
 list.add(s.nextLine(());

Upvotes: 0

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