The relationship between Looper, Handler, and MessageQueue in Android is as follows:
Looper is responsible for creating a message loop for a thread. It retrieves messages from the MessageQueue and dispatches them to the appropriate Handler[1][2][3].
MessageQueue is a queue that stores the messages to be processed by the Looper. Messages are added to the queue by Handlers[1][2][4].
Handler is used to send and process messages and runnables. It enqueues messages into the MessageQueue associated with the Looper of the thread it was created in[1][2][3].
The relationship can be summarized as:
Looper creates a MessageQueue and enters a message dispatch loop, waiting for messages to be added to the queue[2][4].
Handler is used to post messages and runnables to the MessageQueue associated with the Looper of the thread it was created in[1][3].
