In the poem "Bad Man " by Langston Hughes, what literary devices does he use? Also what is the main theme in his poem?

In his poem titled “Bad Man,” Langston Hughes uses a
number of literary devices to help contribute to the effectiveness of the poem.  Among
these devices are the following:

• Simple,
  colloquial language.  The poem is easily accessible and its phrasing is easy to
  understand.


• Repetition for emphasis, as in the repeated
  word “bad” in line 1 and the repeated phrase “I’m a bad, bad man” in lines 1 and
  3.


• Dialect, as in such words as “Everbody” (4) and
  “heaben” (18). Such phrasing helps make the poem sound authentic and also helps it to
  suggest that the speaker is an African American of a lower social class. These words,
  then, help specify the circumstances of the speaker and may help to explain why he
  characterizes himself as he does.


• Movement from general
  to specific. In the first stanza, the speaker announces merely that he is a “bad man”
  but doesn’t say how. In the second stanza, however, he gives particular examples of his
  badness:

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I beats ma’ wife,
an’

I beats ma side gal too.
(7-8)

• Possible
  irony. In the first stanza, the speaker says that he is bad simply “Cause everbody tells
  me so” (2). This phrasing may suggest that the speaker doesn’t actually believe that he
  is genuinely bad.  However, in the second stanza, he ironically offers particular
  examples of his badness (adultery and physical
  abuse).


• Emphatic stress on verbs, as in the repeated and
  metrically emphasized word “beats” in stanza
  2.


• Ambiguity, as in the speaker’s statement in line 2
  that he doesn’t know why he beats his wife and his
  mistress.


• Paradox, as in his claim in stanza three that
  he doesn’t even want to be good; this makes the poem more intriguing and
  mysterious.


• A somewhat shocking climax, as in the claim
  (in the final two lines) that not only is the speaker going to be a “devil” but that he
  wouldn’t go to heaven if he could.  This is another example of paradox, and it also adds
  to the intrigue and mystery of the poem.


• Lack of comment
  by any voice other than the speaker’s.  A different kind of poet might have made the
  speaker more self-pitying; instead, Hughes makes the speaker defiant and unapologetic. 
  Likewise, a different kind of poet might have used the speaker’s words as an opportunity
  to offer moralistic commentary. However, Hughes refrains from indulging in such
  moralizing, letting the speaker speak for himself and letting readers draw their own
  conclusions about him.


• Rhythm, language, and repetition
  that link the poem to the “blues” tradition in
  music.