List of String

List<String> list = Arrays.asList("1", "2", "3");
System.out.println(String.join(", ", list));

Output:

1, 2, 3

List of Object

List<Object> list = Arrays.asList(new Object(), new Object(), new Object());
System.out.println(Arrays.toString(list.toArray()));

Output:

[java.lang.Object@1b6d3586, java.lang.Object@4554617c, java.lang.Object@74a14482]