شیوه درست صدا زدن Superclass ها در Activity اندروید:
// Called after onCreate has finished, use to restore UI state
@Override
public void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState); // Always call the superclass method at FIRST.
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
// Will only be called if the Activity has been
// killed by the system since it was last visible.
}
// Called before subsequent visible lifetimes for an activity process.
@Override
public void onRestart()
{
super.onRestart(); // Always call the superclass method at FIRST.
// Load changes knowing that the Activity has already
// been visible within this process.
}
// Called at the start of the visible lifetime.
@Override
public void onStart()
{
super.onStart(); // Always call the superclass method at FIRST.
// Apply any required UI change now that the Activity is visible.
}
// Called at the start of the active lifetime.
@Override
public void onResume()
{
// Resume any paused UI updates, threads, or processes required
// by the Activity but suspended when it was inactive.
super.onResume(); // Always call the superclass method at LAST.
}
// Called to save UI state changes at the end of the active lifecycle.
@Override
public void onSaveInstanceState(Bundle savedInstanceState)
{
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate and
// onRestoreInstanceState if the process is
// killed and restarted by the run time.
super.onSaveInstanceState(savedInstanceState); // Always call the superclass method at LAST.
}
// Called at the end of the active lifetime.
@Override
public void onPause()
{
// Suspend UI updates, threads, or CPU intensive processes
// that don't need to be updated when the Activity isn't
// the active foreground Activity.
super.onPause(); // Always call the superclass method at LAST.
}
// Called at the end of the visible lifetime.
@Override
public void onStop()
{
super.onStop(); // Always call the superclass method at FIRST.
// Suspend remaining UI updates, threads, or processing
// that aren't required when the Activity isn't visible.
// Persist all edits or state changes
// as after this call the process is likely to be killed.
}
// Sometimes called at the end of the full lifetime.
@Override
public void onDestroy()
{
// Clean up any resources including ending threads,
// closing database connections etc.
super.onDestroy(); // Always call the superclass method at LAST.
}
خلاصه مطب: در متد های onRestoreInstanceState، onStop, onRestart, onStart، ابتدا باید Superclass صدا زده بشه و بعد کدهای شما قرار بگیره. اما در متدهای onDestroy, onPause, onSaveInstanceState, onResume ابتدا باید کدهای شما قرار بگیره و بعد متد Superclass صدا زده بشه.
عدم رعایت این اولویت ها گاهی باعث کندی، crash کردن، memory leak، ناهماهنگی در UI، باگهای DataSaving و امثالش میشه... پس حتماً رعایت کنید.
(شاید درصد کمی از برنامه ها باشند که از این قائده پیروی نمی کنند، اما اون هم با آگاهی کامل از محتوا و مکانیسم Superclass ها.)
منبع: پروفسور Andrew T. Campbell (و گوگل)
http://www.cs.dartmouth.edu/~campbell/cs65/lecture05/lecture05.html
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