onCreate(Bundle SavedInstanceState) SavedInstanceState保存activity状态

//定义
public static final String BUNDLE_KEY_IS_PLAY_BEEP = “mainActivityIsPlayBeep”;
private boolean mIsPlayBeep =false;
当Activity 变得容易被销毁时，Activity的onSaveInstanceState 就会被执行

除非是 用户自己按了back按键

保存的参数 putBoolean（key , value）；

@Override
protected void onSaveInstanceState(Bundle outState)
{
    outState.putBoolean(BUNDLE_KEY_IS_PLAY_BEEP, mIsPlayBeep);
    super.onSaveInstanceState(outState);
}

onCreat 的时候 恢复状态

从savedInStanceState.getBoolean（key ，value）中取出销毁时候存储的数据

当savedInstanceState 为空时，通过getIntent.getBooleanExtra（key ，value） 设置初始的值

protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mApplication = FG8KWApplication.getInstance();

    if (savedInstanceState != null) {
        mIsPlayBeep = savedInstanceState.getBoolean(BUNDLE_KEY_IS_PLAY_BEEP, false);
    }
    else {
        mIsPlayBeep = getIntent().getBooleanExtra(BUNDLE_KEY_IS_PLAY_BEEP, false);
    }

参考：
https://blog.csdn.net/initphp/article/details/11973651
https://blog.csdn.net/da_xin/article/details/79289562