A modern programming language that makes developers happier.

kotlinlang

`Day18`
• Finish lesson 4
    ◦ Activity Life Cycle
        ▪︎ _onCreate_ - one time initializations, layout inflations /_onDestroy_ - destroy everything
        ▪︎ _onStart_ - start objects that only run when activity is on screen / _onRestart_ - anything that runs only if not being created / _onStop_ - stop objects that only run when activity is on screen. permanently save data
        ▪︎ _onPause_ - called when activity loses focus / _onResume_ - called when activity gains focus
    ◦ Fragment Life Cycle (states are the same, but the callbacks are different)
        ▪︎ _onCreate / onCreateView / onStop / onAttach / onActivityCreated / onStart / onResume / onDestroyView / onDestroy / onDetach_ - be aware of fragment specific cautions.. (ex. should inflate layout xmls in onCreateView not in onCreate)
    ◦ Using LifecycleObserver
    ◦ _Process shutdown_ (Android OS takes the state of some of your views and saves them to a _bundle, to RAM_ when you navigate away.)
        ▪︎ _onSaveInstanceState_ - safely save in case app process is torn down by OS. 
            • Should call super method to automatically save basic informations such as backstack info &amp; some data values. 
            • To manually add data to bundle, call putXX methods with key and value. Key must be string. 
            • size of _bundle_ is restricted, varies by device
    ◦ _Configuration changes_ causes the activity to be rebuilt
        ▪︎ example of config change -  user changes device language, plugs in physical device, rotates device
`Self-Comment`
• It’s quite amazing when design pattern I’ve learned in class(but just went through my ear..) appear again. Good to see u observer pattern.
• Managing life cycles seems to be important. For all this time I just used onCreate for initialization, without knowing anything about all these.:face_with_rolling_eyes:
`Goals Tomorrow`
• Halfway to lesson 5 &amp; googling for android ble