course on Kotlin Android App Development, Understanding System Status

Android app development is the process of creating applications that operate across various devices and environments. To ensure that the app functions correctly, understanding the system state of the device and taking appropriate actions when necessary is crucial. In this article, we will explore how to identify the system state in Android apps using Kotlin. By understanding the system state, developers can detect various elements such as app performance, battery consumption, and network status, thereby providing a better user experience.

1. What is System State?

The system state encompasses various properties and behaviors of Android devices. Generally, the key system states we need to check are as follows:

• Device battery status
• Network connection status
• Memory usage
• CPU usage
• Device screen temperature

This information is used to optimize app functions, user interface, performance, and more.

2. Understanding Battery Status

To check the battery status in Android, we use the BatteryManager class. This allows us to obtain the current battery level and power supply status.

2.1 How to Retrieve Battery Status

Here is an example code for retrieving the battery status:

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.BatteryManager
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import android.widget.TextView

class MainActivity : AppCompatActivity() {
    private lateinit var batteryInfo: TextView

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

        batteryInfo = findViewById(R.id.batteryInfo)

        val batteryStatus: Intent? = IntentFilter(Intent.ACTION_BATTERY_CHANGED).let { intentFilter ->
            registerReceiver(null, intentFilter)
        }

        val level: Int = batteryStatus?.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) ?: -1
        val scale: Int = batteryStatus?.getIntExtra(BatteryManager.EXTRA_SCALE, -1) ?: -1
        val batteryPct: Float = level / scale.toFloat() * 100

        batteryInfo.text = "Battery Level: ${batteryPct.toInt()}%"
    }
}

2.2 Basic XML Layout File

The basic XML layout file for executing the above code is as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/batteryInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24sp"/>

</LinearLayout>

3. Understanding Network Status

To check the network status in Android, we use ConnectivityManager. This allows us to check Wi-Fi, mobile data, and disconnected status.

3.1 How to Check Network Status

Here is an example code for checking the network status:

import android.content.Context
import android.net.ConnectivityManager
import android.net.NetworkCapabilities
import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var networkInfo: TextView

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

        networkInfo = findViewById(R.id.networkInfo)

        val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val networkCapabilities = connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)

        val isConnected = networkCapabilities?.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET) == true

        networkInfo.text = if (isConnected) "Internet Connected" else "Internet Not Connected"
    }
}

3.2 XML Layout File

The XML layout to be used with the above code is as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/networkInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24sp"/>

</LinearLayout>

4. Understanding Memory Usage

To assess memory usage, we use ActivityManager. This allows us to check available memory and current usage.

4.1 How to Check Memory Usage

Here is an example code to check memory usage:

import android.app.ActivityManager
import android.content.Context
import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var memoryInfo: TextView

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

        memoryInfo = findViewById(R.id.memoryInfo)

        val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        val memoryInfo = ActivityManager.MemoryInfo()
        activityManager.getMemoryInfo(memoryInfo)

        val availableMemory = memoryInfo.availMem / (1024 * 1024)
        this.memoryInfo.text = "Available Memory: $availableMemory MB"
    }
}

4.2 XML Layout File

The XML layout for executing the above memory usage check code is as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/memoryInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24sp"/>

</LinearLayout>

5. Understanding CPU Usage

To assess CPU usage, we mainly use Debug.MemoryInfo. This allows us to inspect memory usage for the current process. However, checking the overall CPU usage of the system can be complex, and alternative methods are required for that.

Here is an example code that can help determine CPU usage persistence:

import android.os.Bundle
import android.os.Debug
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var cpuInfo: TextView

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

        cpuInfo = findViewById(R.id.cpuInfo)

        val memoryInfo = Debug.MemoryInfo()
        Debug.getMemoryInfo(memoryInfo)

        cpuInfo.text = "Total Memory Usage: ${memoryInfo.totalPss} KB"
    }
}

5.2 XML Layout File

The XML layout for executing the above CPU usage check code is as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/cpuInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24sp"/>

</LinearLayout>

6. Understanding Screen Temperature

To check the temperature of the device, the Android API allows us to retrieve the temperature value as part of the data through the BatteryManager class. The value is presented in tenths of a degree; for example, if 270 is returned, the device’s temperature is 27 degrees.

6.1 How to Retrieve Screen Temperature

Here is a simple example to retrieve the temperature:

import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.BatteryManager
import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var temperatureInfo: TextView

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

        temperatureInfo = findViewById(R.id.temperatureInfo)

        val intent: Intent? = IntentFilter(Intent.ACTION_BATTERY_CHANGED).let { intentFilter ->
            registerReceiver(null, intentFilter)
        }

        val temperature: Int = intent?.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0) ?: 0
        val temperatureCelsius = temperature / 10.0

        temperatureInfo.text = "Battery Temperature: $temperatureCelsius °C"
    }
}

6.2 XML Layout File

The XML layout for executing the above temperature check code is as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/temperatureInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24sp"/>

</LinearLayout>

7. How to Consolidate All System State Information

Now we will explore how to identify each system state and consolidate them. We can integrate all system information (battery status, network status, memory usage, CPU usage, screen temperature) into one screen by using a single Activity.

import android.app.ActivityManager
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.net.ConnectivityManager
import android.net.NetworkCapabilities
import android.os.BatteryManager
import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var statusInfo: TextView

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

        statusInfo = findViewById(R.id.statusInfo)

        val batteryStatus = IntentFilter(Intent.ACTION_BATTERY_CHANGED).let { filter ->
            registerReceiver(null, filter)
        }

        val level = batteryStatus?.getIntExtra(BatteryManager.EXTRA_LEVEL, -1) ?: -1
        val scale = batteryStatus?.getIntExtra(BatteryManager.EXTRA_SCALE, -1) ?: -1
        val batteryPct = level / scale.toFloat() * 100

        val connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val networkCapabilities = connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)
        val isConnected = networkCapabilities?.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET) == true

        val activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        val memoryInfo = ActivityManager.MemoryInfo()
        activityManager.getMemoryInfo(memoryInfo)
        val availableMemory = memoryInfo.availMem / (1024 * 1024)

        val temperature: Int = batteryStatus?.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0) ?: 0
        val temperatureCelsius = temperature / 10.0

        val status = "Battery Level: ${batteryPct.toInt()}%\n" +
                     "Network Status: ${if (isConnected) "Connected" else "Not Connected"}\n" +
                     "Available Memory: $availableMemory MB\n" +
                     "Battery Temperature: $temperatureCelsius °C"

        statusInfo.text = status
    }
}

7.2 XML Layout File

Finally, the XML layout to display all the information can be structured as follows:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/statusInfo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18sp"/>

</LinearLayout>

8. Conclusion

In this tutorial, we explored various methods to identify the system state in Android apps using Kotlin. We examined simple example codes for checking battery status, network status, memory usage, CPU usage, and screen temperature. By effectively utilizing these system information, you can provide users with a more comfortable and efficient app experience.

Based on this knowledge, we hope you will pursue more advanced app development!