我要评论countdowntimer由系统提供
查资料的时候 发现了countdowntimer这个类之后 果断抛弃了以前的倒计时做法
功能:
30秒倒计时 每次间隔1秒
参数:
mc.start();方法开始
mc.cancel();方法结束
new mycountdowntimer(30000, 1000); 第一个参数表示 总的时间为30000毫秒,间隔1000毫秒
直接上代码:
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
*
* 倒计时的类 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, "取消", toast.length_long).show();// toast有显示时间延迟
mc.cancel();
}
public void restart(view view) {
toast.maketext(mainactivity.this, "重新开始", toast.length_long).show();// toast有显示时间延迟
mc.start();
}
/**
* 继承 countdowntimer 防范
*
* 重写 父类的方法 ontick() 、 onfinish()
*/
class mycountdowntimer extends countdowntimer {
/**
*
* @param millisinfuture
* 表示以毫秒为单位 倒计时的总数
*
* 例如 millisinfuture=1000 表示1秒
*
* @param countdowninterval
* 表示 间隔 多少微秒 调用一次 ontick 方法
*
* 例如: countdowninterval =1000 ; 表示每1000毫秒调用一次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("倒计时(" + millisuntilfinished / 1000 + ")...");
}
}
}
//┏┓ ┏┓
//┏┛┻━━━┛┻┓
//┃ ┃
//┃ ━ ┃
//┃ ┳┛ ┗┳ ┃
//┃ ┃
//┃ ┻ ┃
//┃ ┃
//┗━┓ ┏━┛
//┃ ┃ 神兽保佑
//┃ ┃ 代码无bug！
//┃ ┗━━━┓
//┃ ┣┓
//┃ ┏┛
//┗┓┓┏━┳┓┏┛
// ┃┫┫ ┃┫┫
// ┗┻┛ ┗┻┛
布局:
<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>
附:
countdowntimer源码:
/*
* 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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