Câu hỏi phỏng vấn Android
Câu hỏi

What is Handler and what is it used for?

Câu trả lời

A Handler in Android is used to send and process messages and runnables on a specific thread's message queue. It allows you to interact with the main thread (also known as the UI thread) from a background thread, such as a worker thread or a separate process[1][3].

The main use cases for Handler are:

  1. Updating the UI from a background thread: Since you cannot directly update the UI from a background thread, you can use a Handler to post UI updates to the main thread's message queue[1][4].

  2. Scheduling delayed tasks or periodic work: A Handler can be used to schedule tasks to be executed at a specific time in the future or repeatedly at a fixed interval[5].

  3. Communicating between threads: By posting messages to a Handler, you can safely pass data between threads and ensure thread-safe communication[3].

Here's how a Handler works:

  1. A Handler is associated with a thread's message queue and the Looper that processes messages from that queue[3].

  2. When you create a Handler, i...

middle

middle

Gợi ý câu hỏi phỏng vấn

middle

What is RenderScript and when should we (really) use it?

junior

What is the Dalvik Virtual Machine?

middle

What is the difference between ListView and RecyclerView ?

Bình luận

Chưa có bình luận nào

Chưa có bình luận nào