CODEWITHSUNDEEP
javaregexparsingjava.util.scanner
Nick
Nick

Reputation: 2970

Read data from text file with scanner and multiple delimiters in JAVA

I have a text file containg the following data:

20;
1: 39, 63;
2: 33, 7;
16: 33, 7;
3: 45, 27;
4: 8, 67;
5: 19, 47;
6: 15, 40;
...
20: 65, 54;

first integer is the amount of entries in the list.

Each line is an entry. So entry 1 has x y coordinates 39 and 63 respectively. I understand that I can use different delimiters to read the data, but i'm not quite sure how to achieve that. Currently I'm using split().

The following code reads each line, but this obviously doesn't work since the delimiters are not set propperly. Is there a good way to get this to work?

String[] temp = sc.next().split(";");
int productAmount = Integer.parseInt(temp[0]);
sc.nextLine();

for (int i = 0; i < productAmount; i++) {
    int productID = sc.nextInt();
    int x = sc.nextInt();
    int y = sc.nextInt();
    Product product = new Product(x, y, productID);
    productList.add(product);
}

Upvotes: 0

Views: 2833

Answers (3)

Farmer Joe
Farmer Joe

Reputation: 6070

Very similar to what Croo said, but I get a compilation error when I use his method.

In order to avoid matching empty strings by including spaces as delimiters, it makes more sense to me to allow them and use a call to trim to get rid of them.

Also it be useful to know that the Scanner can be given a regex expression as a delimiter and then calls to next can be used to navigate the input.

sc.useDelimiter("[,:;]");
int productAmount = Integer.parseInt(sc.next());
int x, y, productID, i;
for (i = 0; i < productAmount; i++) {
    productID = Integer.parseInt(sc.next().trim());
    x = Integer.parseInt(sc.next().trim());
    y = Integer.parseInt(sc.next().trim());
    productList.add(new Product(x,y,productID));
}

Upvotes: 0

Croo
Croo

Reputation: 1371

If you use

String[] temp = sc.next().split("[ ,:;]");

then your temp variable will hold only the numbers. The string "[ ,:;]" is a regular expression, and it means any character in the square brackets will be a delimiter.

Upvotes: 1

user2030471
user2030471

Reputation:

All of the tokens can be converted to integers after removing the last character from them. You can make use of this property of the given data. Define a method like this:

int integerFromToken(String str) {
    return Integer.valueOf(str.substring(0, str.length() - 1));
}

which returns the integer part of a token (39, returns 39, 63; returns 63 etc.). Now use the method to get integer values from tokens (obtained with sc.next()):

int productID = integerFromToken(sc.next());
int x = integerFromToken(sc.next());
int y = integerFromToken(sc.next());

Upvotes: 1

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