横竖屏切换onSaveInstanceState() 和 onRestoreInstanceState()
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Activity的 onSaveInstanceState() 和 onRestoreInstanceState()并不是生命周期方法,它们不同于 onCreate()、onPause()等生命周期方法,它们并不一定会被触发。当应用遇到意外情况(如:内存不足、用户直接按Home键)由系统销毁一个Activity时,onSaveInstanceState() 会被调用。但是当用户主动去销毁一个Activity时,例如在应用中按返回键,onSaveInstanceState()就不会被调用。因为在这种情况下,用户的行为决定了不需要保存Activity的状态。通常onSaveInstanceState()只适合用于保存一些临时性的状态,而onPause()适合用于数据的持久化保存。
例如,如果activity B启用后位于activity A的前端,在某个时刻activity A因为系统回收资源的问题要被杀掉,A通过onSaveInstanceState将有机会保存其用户界面状态,使得将来用户返回到activity A时能通过onCreate(Bundle)或者onRestoreInstanceState(Bundle)恢复界面的状态。
1.先在onSaveInstanceState里保存横竖屏切换要保留的数据。
protected void onSaveInstanceState(Bundle outState) {super.onSaveInstanceState(outState);outState.putParcelable(KEY_HOSPITAL_INTRODUCTION, mHospitalInfo2);outState.putParcelableArrayList(KEY_DEPTLIST, Deptlist);}
然后再activity的onCreate()方法里得到刚刚保存的数据,这样横竖屏切换的时候就不会出现页面空白了,这样就说明你保存了数据。
protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);if(null != savedInstanceState)mInfo = savedInstanceState.getParcelable(KEY_HOSPITAL_INTRODUCTION); mList = savedInstanceState.getParcelableArrayList(KEY_DEPTLIST);}setContentView(R.layout.main);}
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