Android开发中经常会有倒计时的功能,下面将总结出常见的集中实现方式。
1.直接使用Handler的消息机制来实现
xml布局中文件如下:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" > <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="clickButton" android:text="开始计时" /> </LinearLayout>
java代码如下:
import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.widget.Button; public class FirstActivity extends Activity{ private Button button; private int count = 60; private int COUNT_TIME = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.first_activity); button = (Button) findViewById(R.id.button); } private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { if(count <= 0){ count = 60; button.setText("重新计时"); button.setClickable(true); return; } count--; button.setText(""+count); sendEmptyMessageDelayed(COUNT_TIME,1000); } }; public void clickButton(View view){ handler.sendEmptyMessage(COUNT_TIME); button.setClickable(false); } }
2.使用Timer和TimerTask,结合handler一起实现倒计时
import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.widget.Button; public class FirstActivity extends Activity{ private Button button; private int count = 30; private int COUNT_TIME = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.first_activity); button = (Button) findViewById(R.id.button); } private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { button.setText(""+count); if(count <= 0){ count = 30; button.setClickable(true); button.setText("重新计时"); timerTask.cancel(); //取消该任务 } } }; private Timer timer = new Timer(); private TimerTask timerTask; public void clickButton(View view){ button.setClickable(false); timerTask = new TimerTask() { @Override public void run() { count--; handler.sendEmptyMessage(COUNT_TIME); } }; timer.schedule(timerTask,0,1000); //0秒后,每过一秒钟执行一次该任务 } @Override protected void onDestroy() { super.onDestroy(); //释放资源 if(timerTask != null){ timerTask.cancel(); timerTask = null; } if(timer != null){ timer.cancel(); timer = null; } } }
3.使用android自带的原生倒计时类 CountDownTimer
import android.app.Activity; import android.os.Bundle; import android.os.CountDownTimer; import android.view.View; import android.widget.Button; public class FirstActivity extends Activity{ private Button button; private CountDownTimer timer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.first_activity); button = (Button) findViewById(R.id.button); } public void clickButton(View view){ button.setClickable(false); //第一个参数:倒计时的毫秒数;第二个参数:接收onTick回调的时间间隔 timer = new CountDownTimer(30000, 10) { public void onTick(long millisUntilFinished) { button.setText(millisUntilFinished / 1000 + "秒"); } public void onFinish() { button.setText("重新计时"); button.setClickable(true); } }; timer.start(); } @Override protected void onDestroy() { super.onDestroy(); if(timer != null){ timer.cancel(); } } }
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持菜鸟教程(cainiaojc.com)。
声明:本文内容来源于网络,版权归原作者所有,内容由互联网用户自发贡献自行上传,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任。如果您发现有涉嫌版权的内容,欢迎发送邮件至:notice#cainiaojc.com(发邮件时,请将#更换为@)进行举报,并提供相关证据,一经查实,本站将立刻删除涉嫌侵权内容。