Android example source code file (DateTimeView.java)

This example Android source code file (DateTimeView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, broadcastreceiver, content, contentobserver, context, dateformat, datetimeview, intentfilter, override, show_month_day_year, show_time, simpledateformat, string, tag, text, time, uri, util, utilities, utils

The DateTimeView.java Android example source code

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.BroadcastReceiver;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.Handler;
import android.text.format.Time;
import android.util.AttributeSet;
import android.util.Log;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.widget.TextView;
import android.widget.RemoteViews.RemoteView;

import com.android.internal.R;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

//
// TODO
// - listen for the next threshold time to update the view.
// - listen for date format pref changed
// - put the AM/PM in a smaller font
//

/**
 * Displays a given time in a convenient human-readable foramt.
 *
 * @hide
 */
@RemoteView
public class DateTimeView extends TextView {
    private static final String TAG = "DateTimeView";

    private static final long TWELVE_HOURS_IN_MINUTES = 12 * 60;
    private static final long TWENTY_FOUR_HOURS_IN_MILLIS = 24 * 60 * 60 * 1000;

    private static final int SHOW_TIME = 0;
    private static final int SHOW_MONTH_DAY_YEAR = 1;

    Date mTime;
    long mTimeMillis;

    int mLastDisplay = -1;
    DateFormat mLastFormat;

    private boolean mAttachedToWindow;
    private long mUpdateTimeMillis;

    public DateTimeView(Context context) {
        super(context);
    }

    public DateTimeView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onDetachedFromWindow();
        registerReceivers();
        mAttachedToWindow = true;
    }
        
    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        unregisterReceivers();
        mAttachedToWindow = false;
    }

    @android.view.RemotableViewMethod
    public void setTime(long time) {
        Time t = new Time();
        t.set(time);
        t.second = 0;
        mTimeMillis = t.toMillis(false);
        mTime = new Date(t.year-1900, t.month, t.monthDay, t.hour, t.minute, 0);
        update();
    }

    void update() {
        if (mTime == null) {
            return;
        }

        long start = System.nanoTime();

        int display;
        Date time = mTime;

        Time t = new Time();
        t.set(mTimeMillis);
        t.second = 0;

        t.hour -= 12;
        long twelveHoursBefore = t.toMillis(false);
        t.hour += 12;
        long twelveHoursAfter = t.toMillis(false);
        t.hour = 0;
        t.minute = 0;
        long midnightBefore = t.toMillis(false);
        t.monthDay++;
        long midnightAfter = t.toMillis(false);

        long nowMillis = System.currentTimeMillis();
        t.set(nowMillis);
        t.second = 0;
        nowMillis = t.normalize(false);

        // Choose the display mode
        choose_display: {
            if ((nowMillis >= midnightBefore && nowMillis < midnightAfter)
                    || (nowMillis >= twelveHoursBefore && nowMillis < twelveHoursAfter)) {
                display = SHOW_TIME;
                break choose_display;
            }
            // Else, show month day and year.
            display = SHOW_MONTH_DAY_YEAR;
            break choose_display;
        }

        // Choose the format
        DateFormat format;
        if (display == mLastDisplay && mLastFormat != null) {
            // use cached format
            format = mLastFormat;
        } else {
            switch (display) {
                case SHOW_TIME:
                    format = getTimeFormat();
                    break;
                case SHOW_MONTH_DAY_YEAR:
                    format = getDateFormat();
                    break;
                default:
                    throw new RuntimeException("unknown display value: " + display);
            }
            mLastFormat = format;
        }

        // Set the text
        String text = format.format(mTime);
        setText(text);

        // Schedule the next update
        if (display == SHOW_TIME) {
            // Currently showing the time, update at the later of twelve hours after or midnight.
            mUpdateTimeMillis = twelveHoursAfter > midnightAfter ? twelveHoursAfter : midnightAfter;
        } else {
            // Currently showing the date
            if (mTimeMillis < nowMillis) {
                // If the time is in the past, don't schedule an update
                mUpdateTimeMillis = 0;
            } else {
                // If hte time is in the future, schedule one at the earlier of twelve hours
                // before or midnight before.
                mUpdateTimeMillis = twelveHoursBefore < midnightBefore
                        ? twelveHoursBefore : midnightBefore;
            }
        }
        if (false) {
            Log.d(TAG, "update needed for '" + time + "' at '" + new Date(mUpdateTimeMillis)
                    + "' - text=" + text);
        }

        long finish = System.nanoTime();
    }

    private DateFormat getTimeFormat() {
        int res;
        Context context = getContext();
        if (android.text.format.DateFormat.is24HourFormat(context)) {
            res = R.string.twenty_four_hour_time_format;
        } else {
            res = R.string.twelve_hour_time_format;
        }
        String format = context.getString(res);
        return new SimpleDateFormat(format);
    }

    private DateFormat getDateFormat() {
        String format = Settings.System.getString(getContext().getContentResolver(),
                Settings.System.DATE_FORMAT);
        if (format == null || "".equals(format)) {
            return DateFormat.getDateInstance(DateFormat.SHORT);
        } else {
            try {
                return new SimpleDateFormat(format);
            } catch (IllegalArgumentException e) {
                // If we tried to use a bad format string, fall back to a default.
                return DateFormat.getDateInstance(DateFormat.SHORT);
            }
        }
    }

    private void registerReceivers() {
        Context context = getContext();

        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_TIME_TICK);
        filter.addAction(Intent.ACTION_TIME_CHANGED);
        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
        filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
        context.registerReceiver(mBroadcastReceiver, filter);

        Uri uri = Settings.System.getUriFor(Settings.System.DATE_FORMAT);
        context.getContentResolver().registerContentObserver(uri, true, mContentObserver);
    }

    private void unregisterReceivers() {
        Context context = getContext();
        context.unregisterReceiver(mBroadcastReceiver);
        context.getContentResolver().unregisterContentObserver(mContentObserver);
    }

    private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (Intent.ACTION_TIME_TICK.equals(action)) {
                if (System.currentTimeMillis() < mUpdateTimeMillis) {
                    // The update() function takes a few milliseconds to run because of
                    // all of the time conversions it needs to do, so we can't do that
                    // every minute.
                    return;
                }
            }
            // ACTION_TIME_CHANGED can also signal a change of 12/24 hr. format.
            mLastFormat = null;
            update();
        }
    };

    private ContentObserver mContentObserver = new ContentObserver(new Handler()) {
        @Override
        public void onChange(boolean selfChange) {
            mLastFormat = null;
            update();
        }
    };
}