Easy countdown using the CountDownTimer class
- 2020-06-03 08:17:23
- OfStack
CountDownTimer is provided by the system
When I looked up the data, I found the class CountDownTimer and I decisively abandoned the previous countdown practice
Function:
The 30-second countdown takes place one second at a time
Parameters:
mc. start (); Methods to
mc. cancel (); Methods the end
new MyCountDownTimer (30000, 1000); The first parameter represents a total time of 30,000 milliseconds with an interval of 1,000 milliseconds
Direct 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;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.show);
mc = new MyCountDownTimer(30000, 1000);
mc.start();
}
public void oncancel(View view) {
Toast.makeText(MainActivity.this, " cancel ", Toast.LENGTH_LONG).show();// toast There is a display time delay
mc.cancel();
}
public void restart(View view) {
Toast.makeText(MainActivity.this, " Start all over again ", Toast.LENGTH_LONG).show();// toast There is a display time delay
mc.start();
}
/**
* inheritance CountDownTimer To guard against
*
* rewrite Methods of the parent class onTick() , onFinish()
*/
class MyCountDownTimer extends CountDownTimer {
/**
*
* @param millisInFuture
* Denotes in milliseconds Total countdown
*
* For example, millisInFuture=1000 said 1 seconds
*
* @param countDownInterval
* said interval How many milliseconds call 1 time onTick methods
*
* For example, : countDownInterval =1000 ; each 1000 Ms call 1 time onTick()
*
*/
public MyCountDownTimer(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}
@Override
public void onFinish() {
tv.setText("done");
}
@Override
public void onTick(long millisUntilFinished) {
Log.i("MainActivity", millisUntilFinished + "");
tv.setText(" The countdown (" + millisUntilFinished / 1000 + ")...");
}
}
}
// ┏ ┓ ┏ ┓
// ┏ ┛ ┻ ━ ━ ━ ┛ ┻ ┓
// ┃ ┃
// ┃ ━ ┃
// ┃ ┳ ┛ ┗ ┳ ┃
// ┃ ┃
// ┃ ┻ ┃
// ┃ ┃
// ┗ ━ ┓ ┏ ━ ┛
// ┃ ┃ Beast god bless
// ┃ ┃ The code no BUG !
// ┃ ┗ ━ ━ ━ ┓
// ┃ ┣ ┓
// ┃ ┏ ┛
// ┗ ┓ ┓ ┏ ━ ┳ ┓ ┏ ┛
// ┃ ┫ ┫ ┃ ┫ ┫
// ┗ ┻ ┛ ┗ ┻ ┛
Layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/show"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<Button
android:id="@+id/button1"
android:onClick="oncancel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/show"
android:layout_below="@+id/show"
android:layout_marginLeft="50dp"
android:layout_marginTop="106dp"
android:text="cancel" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button1"
android:layout_below="@+id/button1"
android:layout_marginTop="63dp"
android:onClick="restart"
android:text="restart" />
</RelativeLayout>
The attached:
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);
}
}
}
};
}