Java:String和List互相转换

package demo;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ListDemo {
    public static void main(String[] args) {
        String str = "A,B";
    // 字符串转List
        List<String> list = new ArrayList<>(Arrays.asList(str.split(",")));
        list.add("C");
        // List转字符串
        String line = String.join(",", list);
        System.out.println(line);
        // A,B,C
    }
}