标签： java email imap javamail
答案 0 :(得分：3)
答案 1 :(得分：2)
请注意：
Folder.HOLDS_MESSAGES == 1
Folder.HOLDS_FOLDERS == 2
Folder.HOLDS_FOLDERS & Folder.HOLDS_MESSAGES == 0（总是）
Folder.HOLDS_FOLDERS & Folder.HOLDS_MESSAGES == 0
您可以尝试：Folder.HOLDS_FOLDERS | Folder.HOLDS_MESSAGES等于3
Folder.HOLDS_FOLDERS | Folder.HOLDS_MESSAGES