Android Studio – Countdown timer.

By | 07/06/2019
0 Comment

Today I will show you how to create a countdown timer application using the Android Studio version 3.4.1.
The primary reason why I have not written any Android Studio tutorials is a problem with technical resources.
This version of Android Studio seems more promising for the user, but it also has problems that I have encountered.
One problem I find tedious is the gradle configuration.
Another problem is memory loading during development.
I had to use the cleaning system and the IDE clean and build tool to resume development.
All this happened with a simple example.
Let’s begin this tutorial about Countdown timer application using the Android SDK version 8.0.
You can download this application from Download – Application or from this link.
Start with a now Basic Activity project using Java programming language.
You can use Kotlin if you want.
Configure the build.gradle file in this way:

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buildscript {
    repositories {
        jcenter()
        maven { url 'https://maven.google.com' }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.4.1'
        
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}
 
allprojects {
    repositories {
        jcenter()
        maven { url 'https://maven.google.com' }
    }
}
 
task clean(type: Delete) {
    delete rootProject.buildDir
}

Use this for activity_main.xml file:

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
 
 
    <TextView
        android:id="@+id/text_view_countdown"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textSize="150sp"
        tools:text="10:00" />
 
    <Button
        android:id="@+id/button_start_pause"
        android:layout_width="match_parent"
        android:layout_height="176dp"
        android:layout_below="@+id/text_view_countdown"
        android:layout_centerHorizontal="true"
        android:text="START" />
 
    <Button
        android:id="@+id/button_reset"
        android:layout_width="match_parent"
        android:layout_height="176dp"
        android:layout_below="@+id/button_start_pause"
        android:layout_centerHorizontal="true"
        android:text="RESET" />
</RelativeLayout>

The next file is MainActivity.java:

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package org.ft.countdowntimer;
 
import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
 
import org.w3c.dom.Text;
 
import java.util.Locale;
 
public class MainActivity extends AppCompatActivity {
    private static final long TIME_IN_MILLISECONDS = 600000;
    private TextView myTextViewCountDown;
    private Button myButtonStartPause;
    private Button myButtonReset;
    private CountDownTimer myCountDownTimmer;
    private boolean is_TimerRunning;
    private long mTimerLeftInMillis = TIME_IN_MILLISECONDS;
 
    private CountDownTimer countDownTimer;
    private long timeLeftInMilliseconds = 600000;
    private boolean timeRunning;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
      myTextViewCountDown = findViewById(R.id.text_view_countdown);
      myButtonStartPause = findViewById(R.id.button_start_pause);
      myButtonReset = findViewById(R.id.button_reset);
      myButtonStartPause.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
            if(is_TimerRunning){
                pauseTimer();
            } else {
                startTimer();
            }
          }
      });
      myButtonReset.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View view) {
            resetTimer();
          }
      });
      update_CountDownText();
    }
    private void startTimer(){
        myCountDownTimmer = new CountDownTimer(mTimerLeftInMillis, 1000) {
            @Override
            public void onTick(long miliUntilFinish) {
                mTimerLeftInMillis = miliUntilFinish;
                update_CountDownText();
            }
 
            @Override
            public void onFinish() {
                is_TimerRunning = false;
                myButtonStartPause.setText("Start");
                myButtonStartPause.setVisibility(View.INVISIBLE);
                myButtonReset.setVisibility(View.VISIBLE);
            }
        }.start();
        is_TimerRunning = true;
        myButtonStartPause.setText("pause");
        myButtonReset.setVisibility(View.INVISIBLE);
    }
    private void pauseTimer(){
        myCountDownTimmer.cancel();
        is_TimerRunning = false;
        myButtonStartPause.setText("Start");
        myButtonReset.setVisibility(View.VISIBLE);
    }
    private void resetTimer(){
        mTimerLeftInMillis = TIME_IN_MILLISECONDS;
        update_CountDownText();
        myButtonReset.setVisibility(View.INVISIBLE);
        myButtonStartPause.setVisibility(View.VISIBLE);
    }
    private void update_CountDownText(){
        int minutes = (int) (mTimerLeftInMillis / 1000) /60;
        int seconds = (int) (mTimerLeftInMillis / 1000) %60;
        String timeLeftFormatted = String.format(Locale.getDefault(),"%02d:%02d", minutes, seconds);
        myTextViewCountDown.setText(timeLeftFormatted);
    }
}

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