関連ワード:  how to check if list empty java    how to check if list is empty javascript    how to check if list is not empty java    how to check if list is null or empty java    how to check if linked list is empty java    how to check if list is empty in java 8 using optional    how to check if list string is not empty java    how to check if array list is empty java    how to check for empty list in java    how to check for empty list in javascript