需求：
有多个组件可以开启倒计时，正常情况下默认倒计时时间终了后更新UI，另，用户可以取消指定倒计时。
这里使用CountDownTimer进行倒计时，其中回调函数onFinish是在倒计时终了时回调，onTick是在倒计时开始时回调，用户可以使用CountDownTimer对象的cancel方法取消倒计时。
这样做的好处：不需要使用繁琐的线程去控制倒计时，更方便的进行UI更新。
上代码：
MainActivity
package test.demo.countdowntest;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private Button bt1, bt2, bt3;
private ProgressBar pb1, pb2, pb3;
private MyCount mc1,mc2, mc3;
private boolean mc1Click = false;
private boolean mc2Click = false;
private boolean mc3Click = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bt1 = ((Button) findViewById(R.id.bt1));
bt2 = ((Button) findViewById(R.id.bt2));
bt3 = ((Button) findViewById(R.id.bt3));
bt1.setOnClickListener(this);
bt2.setOnClickListener(this);
bt3.setOnClickListener(this);
pb1 = ((ProgressBar) findViewById(R.id.pb1));
pb2 = ((ProgressBar) findViewById(R.id.pb2));
pb3 = ((ProgressBar) findViewById(R.id.pb3));
mc1 = new MyCount(30000, 1000);
mc1.setPb(bt1, pb1);
mc2 = new MyCount(30000, 1000);
mc2.setPb(bt2, pb2);
mc3 = new MyCount(30000, 1000);
mc3.setPb(bt3, pb3);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.bt1:
if (mc1Click) {
mc1.cancel();
pb1.setVisibility(View.GONE);
mc1Click = false;
} else {
pb1.setVisibility(View.VISIBLE);
mc1.start();
mc1Click = true;
}
break;
case R.id.bt2:
if (mc2Click) {
pb2.setVisibility(View.GONE);
mc2.cancel();
mc2Click = false;
} else {
pb2.setVisibility(View.VISIBLE);
mc2.start();
mc2Click = true;
}
break;
case R.id.bt3:
if (mc3Click) {
pb3.setVisibility(View.GONE);
mc3.cancel();
mc3Click = false;
} else {
pb3.setVisibility(View.VISIBLE);
mc3.start();
mc3Click = true;
}
break;
}
}
class MyCount extends CountDownTimer {
Button mBt;
ProgressBar mPb;
public MyCount(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}
public void setPb(Button bt, ProgressBar pb) {
mBt = bt;
mPb = pb;
}
@Override
public void onFinish() {
mPb.setVisibility(View.GONE);
}
@Override
public void onTick(long millisUntilFinished) {
mBt.setText("请等待30秒(" + millisUntilFinished / 1000 + ")...");
Toast.makeText(MainActivity.this, millisUntilFinished / 1000 + "", Toast.LENGTH_LONG).show();
}
}
}activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
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"
android:orientation="vertical"
tools:context="cn.sh.changxing.countdowntest.MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/bt1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="测试启动1"/>
<ProgressBar
android:id="@+id/pb1"
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:indeterminate="true"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/bt2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="测试启动2"/>
<ProgressBar
android:id="@+id/pb2"
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:indeterminate="true"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/bt3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="测试启动3"/>
<ProgressBar
android:id="@+id/pb3"
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:indeterminate="true"/>
</LinearLayout>
</LinearLayout>以上所述是小编给大家介绍的Android 中不用线程如何实现倒计时，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对编程网网站的支持！
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