Android example source code file (DigitalClock.java)

This example Android source code file (DigitalClock.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, attributeset, calendar, content, contentobserver, digitalclock, formatchangeobserver, handler, os, override, provider, resources, runnable, string, textview, util, utilities

The DigitalClock.java Android example source code

/*
 * Copyright (C) 2006 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.res.Resources;
import android.database.ContentObserver;
import android.os.Handler;
import android.os.SystemClock;
import android.provider.Settings;
import android.text.format.DateFormat;
import android.util.AttributeSet;

import java.util.Calendar;

/**
 * Like AnalogClock, but digital.  Shows seconds.
 *
 * FIXME: implement separate views for hours/minutes/seconds, so
 * proportional fonts don't shake rendering
 */

public class DigitalClock extends TextView {

    Calendar mCalendar;
    private final static String m12 = "h:mm:ss aa";
    private final static String m24 = "k:mm:ss";
    private FormatChangeObserver mFormatChangeObserver;

    private Runnable mTicker;
    private Handler mHandler;

    private boolean mTickerStopped = false;

    String mFormat;

    public DigitalClock(Context context) {
        super(context);
        initClock(context);
    }

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

    private void initClock(Context context) {
        Resources r = mContext.getResources();

        if (mCalendar == null) {
            mCalendar = Calendar.getInstance();
        }

        mFormatChangeObserver = new FormatChangeObserver();
        getContext().getContentResolver().registerContentObserver(
                Settings.System.CONTENT_URI, true, mFormatChangeObserver);

        setFormat();
    }

    @Override
    protected void onAttachedToWindow() {
        mTickerStopped = false;
        super.onAttachedToWindow();
        mHandler = new Handler();

        /**
         * requests a tick on the next hard-second boundary
         */
        mTicker = new Runnable() {
                public void run() {
                    if (mTickerStopped) return;
                    mCalendar.setTimeInMillis(System.currentTimeMillis());
                    setText(DateFormat.format(mFormat, mCalendar));
                    invalidate();
                    long now = SystemClock.uptimeMillis();
                    long next = now + (1000 - now % 1000);
                    mHandler.postAtTime(mTicker, next);
                }
            };
        mTicker.run();
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mTickerStopped = true;
    }

    /**
     * Pulls 12/24 mode from system settings
     */
    private boolean get24HourMode() {
        return android.text.format.DateFormat.is24HourFormat(getContext());
    }

    private void setFormat() {
        if (get24HourMode()) {
            mFormat = m24;
        } else {
            mFormat = m12;
        }
    }

    private class FormatChangeObserver extends ContentObserver {
        public FormatChangeObserver() {
            super(new Handler());
        }

        @Override
        public void onChange(boolean selfChange) {
            setFormat();
        }
    }
}