Services are components that run in the background to perform long-running tasks. They have a lower priority than activities and exist beyond the lifetime of the current activity. Services are implemented by extending the Service class and providing an onBind implementation. Services have a distinct lifecycle including onCreate, onDestroy, and onStartCommand. The easiest service to implement is an on-demand service, which is started by the first request and remains running as long as requests are being processed, terminating once the requested processing is complete.

1. Android Services

2. Services
• Services are components that run in background
• Exist to perform long-running operations
• Service run until it completes it work
• Lower priority the current Activity
• Services are about component lifetime not threading
• Services are component concept
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3. Implement a Service
• Services are implemented by extending the Service class
• Must always provide onBind implementation
• A service has distinct lifecycle
• onCreate
• onDestroy
• onStartCommand for search Intent
• List in manifest with <services> element
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4. On-Demand Services
• Easiest Service to implement is an on-demand service
• Android starts service on first request
• Service remains running as long as requests are being processed
• Service terminates as soon as requested processing completes
• Android provides an identifier for each request
• onStartCommand receives a unique startId with each request
• Indicate that request is complete by calling to stopSelfResult
• Pass startId corresponding to the request you’ve completed
• If Android has passed additional requests, Service remains running
• If that startId is from the most recent request, Service is terminated
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5. Handling unexpected termination
• Android may kill Service prematurely if under resource pressure
• Android can later restart Service
• onStartCommantd return values indicate restart needs
• START_REDELIVER_INTENT
• Start service with intent
• START_STICKY
• START_NOT_STICKY
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6. DEMO
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7. ANY QUESTIONS?
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