Question

这是我的问题：在选择i调用finish（）关闭活动后，我启动了一个活动来选择日期。下一步我重新打开相同的活动，我发现活动没有调用oncreate方法。有没有人可以告诉我为什么？

这是清单文件和样式中的活动。

<activity android:name=".activity.CalendarViewActivity"
      android:theme="@style/calendarview_activity"/>

<style name="calendarview_activity" parent="Theme.AppCompat.Dialog">
    <item name="android:windowBackground">@drawable/calendarview_act_bg</item>
    <item name="colorAccent">@color/blue_toolbar_title</item>
    <item name="android:textColor">@color/colorBlack</item>
    <item name="android:windowShowWallpaper">true</item>
    <item name="windowNoTitle">true</item>
</style>

这是活动代码

public class CalendarViewActivity extends BaseActivity
        implements View.OnClickListener, OnDateSelectedListener, OnMonthChangedListener {
    private MaterialCalendarView mMaterialCV;
    DatabaseReference mTimesheetDailyStatusRef;
    private CalendarDay mMonthDate;
    private TextView tvYear;
    private TextView tvDay;
    private static final int SUBMITTED = 2;
    private static final int UN_SUBMITTED = 1;
    private static final int RESULT_CODE = 200;
    private ValueEventListener mStatusListener;
    private DatabaseReference statusRootRef;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_calendarview_activity);
        initView();
        initData();
    }

    private void initData() {
        statusRootRef = FirebaseDatabase.getInstance().getReference().child(Constants
                .COLLECTION_ENGINEER_ROOT).child(Constants.COLLECTION_TIMESHEETS_STATUS).child
                (getUid());
        mTimesheetDailyStatusRef = statusRootRef
                .child(String.valueOf(Calendar.getInstance().get(Calendar.YEAR)))
                .child(String.valueOf(Calendar.getInstance().get(Calendar.MONTH)));
        CalendarDay calendarDay = CalendarDay.from(Calendar.getInstance());
        setStatus(calendarDay);
    }

    @Override
    protected void onResume() {
        super.onResume();
    }

    private void initView() {
        setSize();
        mMaterialCV = (MaterialCalendarView) findViewById(R.id.calendarview_timesheet);
        mMaterialCV.setWeekDayTextAppearance(getResColor(R.color.colorBlack));
        mMaterialCV.setHeaderTextAppearance(getResColor(R.color.colorBlack));
        mMaterialCV.setOnDateChangedListener(this);
        mMaterialCV.setOnMonthChangedListener(this);
        mMaterialCV.setCurrentDate(Calendar.getInstance());
        Intent intent = getIntent();
        mMonthDate = intent.getParcelableExtra(Constants.KEY_SELECTED_DATE);
        if (mMonthDate != null) {
            mMaterialCV.setSelectedDate(mMonthDate);
            mMaterialCV.setCurrentDate(mMonthDate);
        } else {
            setCurrentDate();
        }
        tvDay = (TextView) findViewById(R.id.calendarview_day);
        tvYear = (TextView) findViewById(R.id.calendarview_year);
        setSelectDataToTop(mMonthDate);
        TextView tvOK = (TextView) findViewById(R.id.choose_day_ok);
        TextView tvCancel = (TextView) findViewById(R.id.choose_day_cancel);
        tvCancel.setTypeface(fontMedium);
        tvOK.setTypeface(fontMedium);
        tvCancel.setOnClickListener(this);
        tvOK.setOnClickListener(this);
    }

    private void setCurrentDate() {
        Calendar c = Calendar.getInstance();
        mMonthDate = CalendarDay.from(c);
    }

    private void setSize() {
        WindowManager m = getWindowManager();
        Display d = m.getDefaultDisplay();
        WindowManager.LayoutParams p = getWindow().getAttributes();
        p.height = (int) (d.getHeight() * 0.85);
        p.width = (int) (d.getWidth() * 0.9);
        p.alpha = 1.0f;
        p.dimAmount = 0.0f;
        getWindow().setAttributes(p);
        getWindow().setGravity(Gravity.TOP);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.choose_day_cancel:
                finish();
                break;
            case R.id.choose_day_ok:
                Intent backIntent = new Intent();
                backIntent.putExtra(Constants.KEY_SELECTED_DATE, mMonthDate);
                setResult(RESULT_CODE, backIntent);
                finish();
                break;
            default:
                break;
        }
    }

    private void setSelectDataToTop(CalendarDay mMonthDate) {
        tvYear.setText(String.valueOf(mMonthDate.getYear()));
        int dayOfWeek = mMonthDate.getCalendar().get(Calendar.DAY_OF_WEEK);
        String monthAndDay = TimeFormatUtil.getDate(mMonthDate.getCalendar().getTimeInMillis());
        tvDay.setText(TimeFormatUtil.getWeekSimple(dayOfWeek) + ", " + monthAndDay);
    }

    @Override
    public void onDateSelected(@NonNull MaterialCalendarView widget, @NonNull CalendarDay date,
                               boolean selected) {
        mMonthDate = date;
        setSelectDataToTop(date);
        mMaterialCV.invalidateDecorators();
    }

    @Override
    public void onMonthChanged(MaterialCalendarView widget, CalendarDay date) {
        mTimesheetDailyStatusRef.removeEventListener(mStatusListener);
        mTimesheetDailyStatusRef = null;
        mStatusListener = null;
        mMonthDate = date;
        setStatus(mMonthDate);
    }

    private void setStatus(final CalendarDay calendarDay) {
        mTimesheetDailyStatusRef = statusRootRef.child(String.valueOf(calendarDay.getYear())).child
                (String.valueOf(calendarDay.getMonth()));
        mStatusListener = new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                ArrayList<CalendarStatusDay> days = new ArrayList<>();
                for (DataSnapshot child : dataSnapshot.getChildren()) {
                    CalendarStatusDay day = child.getValue(CalendarStatusDay.class);
                    days.add(day);
                }
                if (isFinishing()) {
                    return;
                }
                Calendar calendar = Calendar.getInstance();
                ArrayList<CalendarDay> unSubmittedDays = new ArrayList<>();
                unSubmittedDays.clear();
                ArrayList<CalendarDay> submittedDays = new ArrayList<>();
                submittedDays.clear();
                for (CalendarStatusDay day : days) {
                    if (day.getStatus() == SUBMITTED) {
                        calendar.set(calendarDay.getYear(), calendarDay.getMonth(),
                                day.getDayOfmonth());
                        submittedDays.add(CalendarDay.from(calendar));
                    } else if (day.getStatus() == UN_SUBMITTED) {
                        calendar.set(calendarDay.getYear(), calendarDay.getMonth(),
                                day.getDayOfmonth());
                        unSubmittedDays.add(CalendarDay.from(calendar));
                    }
                }
                mMaterialCV.addDecorators(
                        new EventDecorator(getDrawable(R.drawable.submitted_selector),
                                submittedDays));
                mMaterialCV.addDecorator(
                        new EventDecorator(getDrawable(R.drawable.unsubmitted_selector),
                                unSubmittedDays));
                mMaterialCV.addDecorators();
                unSubmittedDays.clear();
                unSubmittedDays = null;
                submittedDays.clear();
                submittedDays = null;
                days.clear();
                days = null;

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        };
        mTimesheetDailyStatusRef.addValueEventListener(mStatusListener);
    }

}

Answer 1

因为活动已在后台运行。如果您正在寻找动作回调，则可以使用startActivityForResult方法并在调用活动的onActivityResult中获得回调。

如果您确实要打开同一活动的新实例，请查找launchMode参数并将其添加到清单参考this

中的活动代码

Answer 2

如果您使用startActivityForResult获取SELECTED DATE，那么您需要覆盖onActivityResult中的Actvity方法。因为当setResult如下所示代码控制转到{之前onActivityResult中的{1}}方法。

Actvity

回调方法从其他活动

获取消息

Intent backIntent = new Intent();
backIntent.putExtra(Constants.KEY_SELECTED_DATE, mMonthDate);
setResult(RESULT_CODE, backIntent);
finish();

重新打开活动，活动不会调用oncreate

2 个答案: