使用CountDownTimer类轻松实现倒计时功能
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
newMyCountDownTimer(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:
packagecom.example.daojishi;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.os.CountDownTimer;
importandroid.util.Log;
importandroid.view.View;
importandroid.widget.TextView;
importandroid.widget.Toast;
/**
*
*@authorbaozi
*
*倒计时的类CountDownTimer
*
*/
publicclassMainActivityextendsActivity{
privateMyCountDownTimermc;
privateTextViewtv;
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView)findViewById(R.id.show);
mc=newMyCountDownTimer(30000,1000);
mc.start();
}
publicvoidoncancel(Viewview){
Toast.makeText(MainActivity.this,"取消",Toast.LENGTH_LONG).show();//toast有显示时间延迟
mc.cancel();
}
publicvoidrestart(Viewview){
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()
*/
classMyCountDownTimerextendsCountDownTimer{
/**
*
*@parammillisInFuture
*表示以毫秒为单位倒计时的总数
*
*例如millisInFuture=1000表示1秒
*
*@paramcountDownInterval
*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()
*
*/
publicMyCountDownTimer(longmillisInFuture,longcountDownInterval){
super(millisInFuture,countDownInterval);
}
@Override
publicvoidonFinish(){
tv.setText("done");
}
@Override
publicvoidonTick(longmillisUntilFinished){
Log.i("MainActivity",millisUntilFinished+"");
tv.setText("倒计时("+millisUntilFinished/1000+")...");
}
}
}
//┏┓┏┓
//┏┛┻━━━┛┻┓
//┃┃
//┃━┃
//┃┳┛┗┳┃
//┃┃
//┃┻┃
//┃┃
//┗━┓┏━┛
//┃┃神兽保佑
//┃┃代码无BUG！
//┃┗━━━┓
//┃┣┓
//┃┏┛
//┗┓┓┏━┳┓┏┛
//┃┫┫┃┫┫
//┗┻┛┗┻┛
布局:
<RelativeLayoutxmlns: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)2008TheAndroidOpenSourceProject
*
*LicensedundertheApacheLicense,Version2.0(the"License");
*youmaynotusethisfileexceptincompliancewiththeLicense.
*YoumayobtainacopyoftheLicenseat
*
*http://www.apache.org/licenses/LICENSE-2.0
*
*Unlessrequiredbyapplicablelaworagreedtoinwriting,software
*distributedundertheLicenseisdistributedonan"ASIS"BASIS,
*WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.
*SeetheLicenseforthespecificlanguagegoverningpermissionsand
*limitationsundertheLicense.
*/
packageandroid.os;
importandroid.util.Log;
/**
*Scheduleacountdownuntilatimeinthefuture,with
*regularnotificationsonintervalsalongtheway.
*
*Exampleofshowinga30secondcountdowninatextfield:
*
*
*newCountDownTimer(30000,1000){
*
*publicvoidonTick(longmillisUntilFinished){
*mTextField.setText("secondsremaining:"+millisUntilFinished/1000);
*}
*
*publicvoidonFinish(){
*mTextField.setText("done!");
*}
*}.start();
*
*
*Thecallsto{@link#onTick(long)}aresynchronizedtothisobjectsothat
*onecallto{@link#onTick(long)}won'teveroccurbeforetheprevious
*callbackiscomplete.Thisisonlyrelevantwhentheimplementationof
*{@link#onTick(long)}takesanamountoftimetoexecutethatissignificant
*comparedtothecountdowninterval.
*/
publicabstractclassCountDownTimer{
/**
*Millissinceepochwhenalarmshouldstop.
*/
privatefinallongmMillisInFuture;
/**
*Theintervalinmillisthattheuserreceivescallbacks
*/
privatefinallongmCountdownInterval;
privatelongmStopTimeInFuture;
/**
*@parammillisInFutureThenumberofmillisinthefuturefromthecall
*to{@link#start()}untilthecountdownisdoneand{@link#onFinish()}
*iscalled.
*@paramcountDownIntervalTheintervalalongthewaytoreceive
*{@link#onTick(long)}callbacks.
*/
publicCountDownTimer(longmillisInFuture,longcountDownInterval){
mMillisInFuture=millisInFuture;
mCountdownInterval=countDownInterval;
}
/**
*Cancelthecountdown.
*/
publicfinalvoidcancel(){
mHandler.removeMessages(MSG);
}
/**
*Startthecountdown.
*/
publicsynchronizedfinalCountDownTimerstart(){
if(mMillisInFuture<=0){
onFinish();
returnthis;
}
mStopTimeInFuture=SystemClock.elapsedRealtime()+mMillisInFuture;
mHandler.sendMessage(mHandler.obtainMessage(MSG));
returnthis;
}
/**
*Callbackfiredonregularinterval.
*@parammillisUntilFinishedTheamountoftimeuntilfinished.
*/
publicabstractvoidonTick(longmillisUntilFinished);
/**
*Callbackfiredwhenthetimeisup.
*/
publicabstractvoidonFinish();
privatestaticfinalintMSG=1;
//handlescountingdown
privateHandlermHandler=newHandler(){
@Override
publicvoidhandleMessage(Messagemsg){
synchronized(CountDownTimer.this){
finallongmillisLeft=mStopTimeInFuture-SystemClock.elapsedRealtime();
if(millisLeft<=0){
onFinish();
}elseif(millisLeft<mCountdownInterval){
//notick,justdelayuntildone
sendMessageDelayed(obtainMessage(MSG),millisLeft);
}else{
longlastTickStart=SystemClock.elapsedRealtime();
onTick(millisLeft);
//takeintoaccountuser'sonTicktakingtimetoexecute
longdelay=lastTickStart+mCountdownInterval-SystemClock.elapsedRealtime();
//specialcase:user'sonTicktookmorethanintervalto
//complete,skiptonextinterval
while(delay<0)delay+=mCountdownInterval;
sendMessageDelayed(obtainMessage(MSG),delay);
}
}
}
};
}