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网站的支持！