令人困惑的 Android Activity 生命周期行为
我通过重写每个生命周期方法编写了一个简单的程序，除了 onRestoreInstanceState(Bundle savingInstanceState) 之外，一切都按我的预期工作。
我重写了该方法，
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Toast.makeText(getBaseContext(), "onRestoreInstanceState - Activity1 ", Toast.LENGTH_SHORT).show();
}
但它永远不会被调用。
我也覆盖了 onSaveInstanceState(Bundle outState)，我可以看到系统调用它，但看不到 onRestoreInstanceState(Bundle savingInstanceState)。当我按后退按钮左右时，我可以看到系统调用 onRestore()、OnStart() 和 onResume()，并且UI（仅两个按钮）正确显示。
不调用onRestoreInstanceState(Bundle savingInstanceState)怎么可能恢复UI？我只做 setContentView(R.layout.main) 是 onCreate(savedInstanceState)。那么它如何在不调用 onCreate() 或 onRestoreInstanceState() 的情况下恢复 UI？
非常感谢有人对此有所了解。
谢谢。
I did a simple program by overriding each of the lifecycle methods and everything works as I'd expect, except for onRestoreInstanceState(Bundle savedInstanceState).
I overrode the method as
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
Toast.makeText(getBaseContext(), "onRestoreInstanceState - Activity1 ", Toast.LENGTH_SHORT).show();
}
But it never gets called.
I overrode onSaveInstanceState(Bundle outState) too and I can see the system calling it, but never the onRestoreInstanceState(Bundle savedInstanceState). When I press back button or so, I can see that the system calls onRestore(), OnStart() and onResume(), and the UI (just two buttons) are displayed correctly.
How is it possible that the UI is restored without calling onRestoreInstanceState(Bundle savedInstanceState)? I only do setContentView(R.layout.main) is onCreate(savedInstanceState). So how does it restore the UI without calling either onCreate() or onRestoreInstanceState()?
Would really appreciate somebody shedding some light on this.
Thank you.
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这里的文档有点令人困惑，但我认为这个方法只是作为 onCreate 处理存储状态的一种替代，发生在循环的后期。仅当活动被销毁并使用状态重新创建时才会调用它；这最常发生在方向改变期间。它无意于处理活动之间的普通转换期间的状态。
另请参阅onSaveInstanceState () 和 onRestoreInstanceState ()
The documentation here is a bit confusing, but I think this method is only intended as a kind of stand-in for onCreate's handling of stored state, occurring later in the cycle. It's only called if the activity is destroyed and re-created with state; this would most commonly happen during an orientation change. It's not intended to handle state during ordinary transitions between activities.
See also onSaveInstanceState () and onRestoreInstanceState ()