Android countdown CountDownTimer note

Android countdown CountDownTimer note

Easy countdown for Android: CountDownTimer

CountDownTimer provided by the system

When I checked the information, I found the CountDownTimer class and decisively abandoned the previous countdown practice.

Function:

30 seconds countdown interval: 1 second

Parameters:

Mc. start (); Method start

Mc. cancel (); Method end

New MyCountDownTimer (30000,100 0); the first parameter indicates that the total time is 30000 milliseconds, with an interval of 1000 milliseconds

Directly run the Code:

Package com. example. daojishi; import android. app. activity; import android. OS. bundle; import android. OS. countDownTimer; import android. util. log; import android. view. view; import android. widget. textView; import android. widget. toast;/***** @ author baozi ** countdown class CountDownTimer **/public class MainActivity extends Activity {private MyCountDownTimer mc; private TextView TV; @ Overrideprotected void onCreate (Bu Ndle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); TV = (TextView) findViewById (R. id. show); mc = new MyCountDownTimer (30000,100 0); mc. start ();} public void oncancel (View view) {Toast. makeText (MainActivity. this, "cancel", Toast. LENGTH_LONG ). show (); // toast has a display time delay mc. cancel ();} public void restart (View view) {Toast. makeText (MainActivity. this, "Start again", Toast. LE NGTH_LONG ). show (); // toast has a display time delay mc. start ();}/*** inherits CountDownTimer prevention ** override the methods onTick () and onFinish () of the parent class () */class MyCountDownTimer extends CountDownTimer {/***** @ param millisInFuture * indicates the total number of Countdown times in milliseconds. ** for example, millisInFuture = 1000 indicates 1 second. ** @ param countDownInterval * indicates interval: How many microseconds does one onTick method call? ** example: countDownInterval = 1000; indicates that onTick () **/public MyCountDownTimer (long millisInFuture, lo Ng countDownInterval) {super (millisInFuture, countDownInterval) ;}@ Overridepublic void onFinish () {TV. setText ("done") ;}@ Overridepublic void onTick (long millisUntilFinished) {Log. I ("MainActivity", millisUntilFinished + ""); TV. setText ("Countdown (" + millisUntilFinished/1000 + ")... ");}}} // please wait until then // zookeeper // zookeeper without any bugs! // Zookeeper has been completed before // zookeeper has been executed before being executed ┛ ┗ ┻ ┛

Layout:

Appendix:

CountDownTimer source code:

/* * Copyright (C) 2008 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.os;import android.util.Log;/** * Schedule a countdown until a time in the future, with * regular notifications on intervals along the way. * * Example of showing a 30 second countdown in a text field: * * 
 * new CountDownTimer(30000, 1000) { * *     public void onTick(long millisUntilFinished) { *         mTextField.setText("seconds remaining: " + millisUntilFinished / 1000); *     } * *     public void onFinish() { *         mTextField.setText("done!"); *     } *  }.start(); * 
 * * The calls to {@link #onTick(long)} are synchronized to this object so that * one call to {@link #onTick(long)} won't ever occur before the previous * callback is complete.  This is only relevant when the implementation of * {@link #onTick(long)} takes an amount of time to execute that is significant * compared to the countdown interval. */public abstract class CountDownTimer {    /**     * Millis since epoch when alarm should stop.     */    private final long mMillisInFuture;    /**     * The interval in millis that the user receives callbacks     */    private final long mCountdownInterval;    private long mStopTimeInFuture;    /**     * @param millisInFuture The number of millis in the future from the call     *   to {@link #start()} until the countdown is done and {@link #onFinish()}     *   is called.     * @param countDownInterval The interval along the way to receive     *   {@link #onTick(long)} callbacks.     */    public CountDownTimer(long millisInFuture, long countDownInterval) {        mMillisInFuture = millisInFuture;        mCountdownInterval = countDownInterval;    }    /**     * Cancel the countdown.     */    public final void cancel() {        mHandler.removeMessages(MSG);    }    /**     * Start the countdown.     */    public synchronized final CountDownTimer start() {        if (mMillisInFuture <= 0) {            onFinish();            return this;        }        mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;        mHandler.sendMessage(mHandler.obtainMessage(MSG));        return this;    }    /**     * Callback fired on regular interval.     * @param millisUntilFinished The amount of time until finished.     */    public abstract void onTick(long millisUntilFinished);    /**     * Callback fired when the time is up.     */    public abstract void onFinish();    private static final int MSG = 1;    // handles counting down    private Handler mHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            synchronized (CountDownTimer.this) {                final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();                if (millisLeft <= 0) {                    onFinish();                } else if (millisLeft < mCountdownInterval) {                    // no tick, just delay until done                    sendMessageDelayed(obtainMessage(MSG), millisLeft);                } else {                    long lastTickStart = SystemClock.elapsedRealtime();                    onTick(millisLeft);                    // take into account user's onTick taking time to execute                    long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();                    // special case: user's onTick took more than interval to                    // complete, skip to next interval                    while (delay < 0) delay += mCountdownInterval;                    sendMessageDelayed(obtainMessage(MSG), delay);                }            }        }    };}

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