Assemble a single string with several strings from an ArrayList in Java

Question:

How can I take in a simplified way several Strings from an ArrayList and join them in just one variable of type String? I'm new to Java and I'm having trouble completing this change in a simplified way, avoiding unnecessary and long lines of code.

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

 Saída: ["Campo1, Campo2, Campo3"]

My String variable should look like this:

String fields = "Campo1 Campo2 Campo3";

Answer:

Use o método join() da classe String:

String fields = String.join(" ", fields_list);

_{Note: Requires JAVA 8}