android: 用CountDownTimer实现倒计时

一，代码：

xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activity.ToolsActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="162dp"
        android:layout_marginEnd="159dp"
        android:layout_marginBottom="631dp"
        android:text="打电话"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/vbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="172dp"
        android:layout_marginEnd="149dp"
        android:layout_marginBottom="285dp"
        android:text="开始倒计时"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <TextView
        android:id="@+id/timeView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="170dp"
        android:layout_marginTop="135dp"
        android:layout_marginEnd="184dp"
        android:layout_marginBottom="170dp"
        android:text="timeView"
        app:layout_constraintBottom_toTopOf="@+id/vbutton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

</androidx.constraintlayout.widget.ConstraintLayout>

java

package com.example.okdemo1.activity;

import android.app.ActivityOptions;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

import com.example.okdemo1.MainActivity;
import com.example.okdemo1.R;

public class ToolsActivity extends AppCompatActivity {

    private boolean isTimerFinished = true;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_tools);

        //给按钮增加点击事件
        Button vButton = findViewById(R.id.vbutton);
        vButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (isTimerFinished == false) {
                    Toast.makeText(ToolsActivity.this, "倒计时还没有结束！", Toast.LENGTH_LONG).show();
                    return;
                }

                TextView timeView = findViewById(R.id.timeView);
                int time=60;    //倒计时多少秒
                isTimerFinished = false;
                CountDownTimer timer = new CountDownTimer(time * 1000, 1000) {
                    @Override
                    public void onTick(long millisUntilFinished) {
                        //每隔countDownInterval秒会回调一次onTick()方法
                        timeView.setText("还剩"+(millisUntilFinished / 1000)+"秒");
                    }

                    @Override
                    public void onFinish() {
                        isTimerFinished = true;
                    }
                };
                timer.start();
            }
        });
    }
}

 

二，测试效果: