咨询：new Handler()与new Handler(Looper.myLooper())是否存在差异？

Short answer: In almost all practical scenarios, these two lines of code are completely equivalent — they end up associating the Handler with the same Looper from the current thread. Let me break down why:

• First, let's look at how the no-argument Handler constructor works under the hood. Internally, it directly delegates to the constructor that takes a Looper parameter, passing in exactly Looper.myLooper() as the argument. So new Handler() is just syntactic sugar for new Handler(Looper.myLooper()).
• As you noted, Looper.myLooper() returns the Looper instance tied to the current thread, or null if the thread hasn't initialized a Looper (e.g., a regular worker thread that never called Looper.prepare()). In either case, both constructor calls will behave identically:
  • If there's a valid Looper for the current thread, both will create a Handler linked to that Looper's message queue.
  • If there's no Looper (returns null), both will throw a RuntimeException with a message like "Can't create handler inside thread that has not called Looper.prepare()".

The only real difference is readability: explicitly passing Looper.myLooper() makes your intent clearer for other developers reading the code, whereas the no-argument constructor is more concise. But functionally, they do exactly the same thing.

内容的提问来源于stack exchange，提问作者d3xter