Java Read Comma Separated File Into Arraylist
How to split a comma separated String in Coffee? Regular Expression Case
You can use theCord.split up() function or StringTokenizer grade to split a comma-separated String in Java. Since splitting a String is a very common functionality, Coffee designers take provided a couple of carve up() methods on coffee.lang.String form itself. These split() function takes a regular expression and split the String accordingly. In social club to parse a comma-delimited String, y'all tin but provide a "," as a delimiter and it will return an array of Cord containing individual values. The separate() function internally uses Java's regular expression API (java.util.regex) to practice its job.
If y'all are non very familiar with the regular expression then you tin also utilize the StringTokenizer class, which can also separate a comma-delimited String merely StringTokenizer is an one-time class and non recommended.
You should ever endeavor to utilise the carve up() function from java.lang.Cord class, as whatever performance improvement will probable happen on this method than the StringTokenizer class. Allow's see a couple of examples to split a comma-separated String in Coffee.
By the way, if yous are a complete beginner into Regular expression and don't understand these magical symbols then I highly recommend you join these all-time Regular expression courses. It'south a great collection of online courses to learn everything about RegEx yous want to know.
Divide a comma-delimited String into an Array - Example
This is the simplest example of splitting a CSV String in Coffee. All you lot need to do is call the separate() function with delimiter as shown in the following case. This method splits the String-based upon given regular expression and returns a String array with private Cord values.
package beginner; import java.util.Arrays; /** * Java Program to split a CSV String into individual Cord values. This * program shows two ways to carve up the CSV String and create a String array out * of it, first by using String.split() method and 2nd, past using * StringTokenizer grade. * * @writer WINDOWS * */ public class HelloWorldApp { public static void principal(String... args) { Cord CSV = "Google,Apple,Microsoft"; Cord[] values = CSV.split(","); System.out.println(Arrays.toString(values)); } } Output :[Google, Apple tree, Microsoft]
Y'all can too create an ArrayList by splitting a comma-separated Cord every bit shown below:
ArrayList list = new ArrayList(Arrays.asList(values)
If your comma-separated String too contains whitespace between values like "Google, Microsoft, Apple" then yous tin can use the following regular expression to split the CSV string besides as go rid of the leading and abaft whitespaces from private values.
String CSV = "Google, Apple, Microsoft"; String[] values = CSV.separate("\\s*,\\south*"); System.out.println(Arrays.toString(values));
Here \\due south* is the regular expression to observe goose egg or more infinite. \s is the metacharacter to find whitespace including tabs. since \ (forward slash) requires escaping in Java it becomes \\ (double slash) and \s becomes \\s.
Now coming to * (star or asterisk), it'south another special character in regular expression which means any number of times. So \\south* means space whatever number of times.
Dissever Comma Separated Cord using StringTokenizer in Coffee
And, hither is an example of how you can utilise StringTokenizer to split a comma-separated String into a String array. StringTokenizer is a utility class in java.util package, which accepts a String and breaks into tokens.
By default, StringTokenizer breaks the String on whitespace but you can pass the token yous want to employ. For example, to break a comma-separated String into private tokens, we can pass comma (,) as a token as shown in the following instance.
One time you exercise that, you can just iterate over StringTokenizer using hasMoreTokens() and retrieve values using nextToken(), similar to how you lot iterate over ArrayList using Iterator.
public class HelloWorldApp { public static void main(String... args) { Cord CSV = "Google,Apple tree,Microsoft"; StringTokenizer tokenizer = new StringTokenizer(CSV, ","); while (tokenizer.hasMoreTokens()) { System.out.println(tokenizer.nextToken()); } } } Output Google Apple Microsoft
That'due south all about how to split a comma-separated String in Coffee. Y'all can apply the carve up() function to parse comma-delimited String. Just remember that it takes regular expression only to break CSV string, y'all just need to pass "," if your String is like "a,b,c" i.e. there is no space betwixt 2 values. If there is space between values and then you tin utilize the regular expression "\\southward*,\\due south*" to remove the space around individual values.
Other Coffee String tutorials from this weblog:
- How to reverse String in Coffee using recursion? (solution)
- How to compare ii Sring in Coffee? (solution)
- How to format Cord in Coffee? (example)
- How to convert double to String in Java? (solution)
- How to check if two Cord are Anagram? (solution)
- How to convert Date to Cord in Java? (respond)
- How String in switch instance works in Java? (answer)
- 21 String interview questions with answers (questions)
- 100+ data construction interview questions (answers)
- 25 Recursion exercise for Beginners (recursion questions)
- x Dynamic Programming interview questions (DP questions)
- 10 Microservice questions with answers (microservices)
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Source: https://javarevisited.blogspot.com/2015/12/how-to-split-comma-separated-string-in-java-example.html
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