Chronometer example (Kotlin)

 Android example of using Chronometer (count-up and count-down) widget, with Kotlin

Layout with Chronometer

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:orientation="vertical"
    tools:context=".MainActivity"
    android:layout_margin="10dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:text="Chronometer Example (Kotlin)"
        android:layout_gravity="center"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Android-er.blogspot.com"
        android:layout_gravity="center"/>
    <Chronometer
        android:id="@+id/chronometer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="34dp"
        android:textStyle="bold"/>
    <Button
        android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start (Count Up)"/>
    <Button
        android:id="@+id/stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Stop"/>
    <Button
        android:id="@+id/reset"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Reset"/>

    <Chronometer
        android:id="@+id/chronometerDn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="34dp"
        android:textStyle="bold"
        android:countDown="true"/>
    <Button
        android:id="@+id/startDn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start (Count Down)"/>
    <Button
        android:id="@+id/stopDn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Stop"/>
    <Button
        android:id="@+id/resetDn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Reset"/>

</LinearLayout>

Android Kotlin code

package com.blogspot.android_er.androidchronometer

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.SystemClock
import android.widget.Button
import android.widget.Chronometer
import android.widget.Toast

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val myChronometer = findViewById<Chronometer>(R.id.chronometer)
        val btnStart = findViewById<Button>(R.id.start)
        val btnStop = findViewById<Button>(R.id.stop)
        val btnReset = findViewById<Button>(R.id.reset)

        btnStart.setOnClickListener(){
            myChronometer.start();
            Toast.makeText(this,
                    "myChronometer.start()",
                    Toast.LENGTH_LONG).show()
        }

        btnStop.setOnClickListener(){
            myChronometer.stop();
            Toast.makeText(this,
                    "myChronometer.stop()",
                    Toast.LENGTH_LONG).show()
        }

        btnReset.setOnClickListener(){
            myChronometer.base = SystemClock.elapsedRealtime()
            Toast.makeText(this,
                    "myChronometer.base = SystemClock.elapsedRealtime()",
                    Toast.LENGTH_LONG).show()
        }

        val myChronometerDn = findViewById<Chronometer>(R.id.chronometerDn)
        val btnStartDn = findViewById<Button>(R.id.startDn)
        val btnStopDn = findViewById<Button>(R.id.stopDn)
        val btnResetDn = findViewById<Button>(R.id.resetDn)

        btnStartDn.setOnClickListener(){
            myChronometerDn.base = SystemClock.elapsedRealtime() + 10000
            myChronometerDn.start()
            Toast.makeText(this,
                    "myChronometerDn.base = " +
                            "SystemClock.elapsedRealtime() + 10000 \n" +
                            "myChronometerDn.start()",
                    Toast.LENGTH_LONG).show()
        }

        btnStopDn.setOnClickListener(){
            myChronometerDn.stop()
            Toast.makeText(this,
                    "myChronometerDn.stop()",
                    Toast.LENGTH_LONG).show()
        }

        btnResetDn.setOnClickListener(){
            myChronometerDn.base = SystemClock.elapsedRealtime()
            Toast.makeText(this,
                    "myChronometerDn.base = SystemClock.elapsedRealtime()",
                    Toast.LENGTH_LONG).show()
        }

    }
}

Simple example using TextClock with Kotlin

TextClock can display the current date and/or time as a formatted string. It's a simple example of using TextClock with Kotlin.

layout XML with TextClock

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextClock
        android:id="@+id/mytextclock"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="italic|bold"
        android:textSize="40dp"
        android:format12Hour="hh:mm:ss a"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

Access TextClock using Kotlin

package com.blogspot.android_er.androidtextclock

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.TextClock
import android.widget.Toast

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val myTextClock = findViewById<TextClock>(R.id.mytextclock)
        myTextClock.setOnClickListener{
            val s = myTextClock.text
            Toast.makeText(this, s, Toast.LENGTH_LONG).show()
        }

    }
}

Get Android and SDK version using Kotlin

 Exercise to get Android device info and compile SDK version using Kotlin.

Run on Android Emulator of Android 10

Run on Redmi 5 Plus (Android 8.1.0)

MainActivity.kt

package com.blogspot.android_er.androidinfo

import android.os.Build
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
import androidx.annotation.RequiresApi

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val manufacturer = Build.MANUFACTURER
        val model = Build.MODEL
        val release = Build.VERSION.RELEASE

        val pkgInfo = packageManager.getPackageInfo(packageName, 0)
        val appInfo = pkgInfo.applicationInfo
        val targetSdkVersion = appInfo.targetSdkVersion
        val minSdkVersion = appInfo.minSdkVersion

        //Display system and SDK info for reference
        val tvInfo = findViewById<TextView>(R.id.info)
        tvInfo.setText(manufacturer + "\n"  +
                model + "\n" +
                "Android: " + release + "\n" +
                "targetSdkVersion: " + targetSdkVersion + "\n" +
                "minSdkVersion: " + minSdkVersion)
    }
}

layout xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Android-er"
        android:textStyle="bold"
        android:textSize="34dp" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="android-er.blogspot.com   " />
    <TextView
        android:id="@+id/info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textStyle="italic"
        android:textSize="30dp"/>

</LinearLayout>