Java Split CSV String – Convert String to List Example

Learn to split string by comma or space and store in array or arraylist. Use given Java program to convert string to List in Java.

1. Convert String to List Using Regular Expression

We can use regular expression "\\s*,\\s*" to match comma in CSV string and then do Java string split with String.split() method to convert string to list.

import java.util.Arrays;
import java.util.List;

public class CSVSplitExample 
{
	public static void main(String[] args) 
	{
		String alpha = "how, to, do, in, java";

		//Remove whitespace and split by comma
		List<String> result = Arrays.asList(alpha.split("\\s*,\\s*"));

		System.out.println(result);
	}

}

Program Output.

[how, to, do, in, java]

This resulting ArrayList is a fixed-size unmodifiable read-only list backed by the array. It means you cannot add or remove elements from this list. If you want a modifiable list then use next approach.

Notice split() function returns string array. So you can modify above example to split string to array as well.

2. Convert CSV to Mutable ArrayList

To get the mutable arraylist, copy all elements from read-only list received from above example into a new ArrayList object.

import java.util.Arrays;
import java.util.List;

public class CSVSplitExample2 
{

	public static void main(String[] args) 
	{
		String alpha = "how, to, do, in, java";

		//Typecast to ArrayList
		List<String> result = new ArrayList<String>( Arrays.asList(alpha.split("\\s*,\\s*")) );

		System.out.println(result);

		result.add("com");

		System.out.println(result);
	}
}

[how, to, do, in, java, com]

3. Convert List to CSV String – Java 8

If we want to convert list to CSV, then we can use String.join() method provided by Java 8.

import java.util.Arrays;
import java.util.List;

public class JavaListToStringExample 
{
	public static void main(String[] args) {
		 
		List<String> list = Arrays.asList("how", "to", "do", "in", "java");

		String result = String.join("-", list);		//delimited by comma
		System.out.println(result);
		
		String result2 = String.join(" ", list);	//delimited by space
		System.out.println(result2);
    }
}

Output: 

Program Output.

how-to-do-in-java
how to do in java

Above examples will help you to convert String to List and also convert List to String in Java.

Happy Learning !!

Read More:

Read/Write CSV file with OpenCSV
Read/Write CSV file with SuperCSV
3 examples to parse CSV files
Join String in Java 8