A handler is basically a message queue. You post a message to it, and it will eventually process it by calling its run method and passing the message to it. Since these run calls will always occur in the order of messages received on the same thread, it allows you to serialize events..
Hereof, what is the use of handler?
A Handler allows communicating back with UI thread from other background thread . This is useful in android as android doesn't allow other threads to communicate directly with UI thread. A Handler allows you to send and process Message and Runnable objects associated with a thread's MessageQueue.
Also Know, does handler create a new thread? Handler is part of the Android system's framework for managing threads. A Handler object receives messages and runs code to handle the messages. Normally, you create a Handler for a new thread, but you can also create a Handler that's connected to an existing thread.
Also asked, what is a handler in Java?
A handler is basically a message queue. You post a message to it, and it will eventually process it by calling its run method and passing the message to it. Since these run calls will always occur in the order of messages received on the same thread, it allows you to serialize events.
What is the difference between thread and handler thread in Android?
Threads are generic processing tasks that can do most things, but one thing they cannot do is update the UI. Handlers on the other hand are background threads that allow you to communicate with the UI thread (update the UI).
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A Handler allows you to send and process Message and Runnable objects associated with a thread's MessageQueue . Each Handler instance is associated with a single thread and that thread's message queue. 
