How to turn ON the Torch!

 Do you wonder how can we lit the light of our Android Phone's Torch?

Here we have a very small code to do that!

We only need just one permission in our AndroidManifest.xml to turn ON the light:

<uses-feature
    android:name="android.hardware.camera"
    android:required="false" />
<uses-permission android:name="android.permission.CAMERA" />

So after adding this, the AndroidManifest.xml looks like this:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <uses-feature
        android:name="android.hardware.camera"
        android:required="false" />
    <uses-permission android:name="android.permission.CAMERA" />

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Torch">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Then in the activity_main.xml, create a button for user interaction:

<Button
    android:id="@+id/torchButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Toggle Flashlight" />

Here is the full content of the activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <Button
        android:id="@+id/torchButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Toggle Flashlight" />
</LinearLayout>

Finally in the MainActivity.java we have to do multiple thing:

1. Create object of CameraManager which is used to interact with the camera hardware, in this case, to control the flashlight.

2. Create a String object cameraId which holds the ID of the camera (typically used to refer to the back camera here).

3. Create a boolean isTorchOn to track whether the torch is currently on or off.

private CameraManager cameraManager;
private String cameraId;
private boolean isTorchOn = false;

4. The getSystemService(CAMERA_SERVICE) call retrieves a system-level service to access the camera hardware.

cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);

5. Add a try catch block:

• This block attempts to get a list of camera IDs using cameraManager.getCameraIdList(). The first item in the list ([0]) corresponds to the back camera.

• If there’s an error in accessing the camera, it catches the CameraAccessException and prints the stack trace.

try {
    cameraId = cameraManager.getCameraIdList()[0]; // Use the back camera
} catch (CameraAccessException e) {
    e.printStackTrace();
}

6. Set up the Button for Toggling Torch:

A Button named torchButton is found using findViewById(R.id.torchButton), which references the button element defined in the XML layout file.

The setOnClickListener method attaches a click listener to the button, so when it’s clicked, the toggleTorch() method will be called.

Button torchButton = findViewById(R.id.torchButton);
torchButton.setOnClickListener(view -> toggleTorch());

7. toggleTorch() Method: This method toggles the flashlight (torch) on and off.

It checks the isTorchOn flag:

If the torch is on (isTorchOn is true), it calls cameraManager.setTorchMode(cameraId, false) to turn the flashlight off.

If the torch is off (isTorchOn is false), it calls cameraManager.setTorchMode(cameraId, true) to turn it on.

After toggling the torch, it updates the isTorchOn flag accordingly.

private void toggleTorch() {
    try {
        if (isTorchOn) {
            // Turn off the torch
            cameraManager.setTorchMode(cameraId, false);
            isTorchOn = false;
        } else {
            // Turn on the torch
            cameraManager.setTorchMode(cameraId, true);
            isTorchOn = true;
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

So the complete code of MainActivity.java will be:

package com.prashantsj.apps.torch;

import android.app.Activity;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraManager;
import android.os.Bundle;
import android.widget.Button;

public class MainActivity extends Activity {

    private CameraManager cameraManager;
    private String cameraId;
    private boolean isTorchOn = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initialize the CameraManager
        cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);

        // Get the camera ID (for the back camera)
        try {
            cameraId = cameraManager.getCameraIdList()[0]; // Use the back camera
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }

        // Button to toggle torch
        Button torchButton = findViewById(R.id.torchButton);
        torchButton.setOnClickListener(view -> toggleTorch());
    }

    private void toggleTorch() {
        try {
            if (isTorchOn) {
                // Turn off the torch
                cameraManager.setTorchMode(cameraId, false);
                isTorchOn = false;
            } else {
                // Turn on the torch
                cameraManager.setTorchMode(cameraId, true);
                isTorchOn = true;
            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }
}

How to Update a Number Every Second (Latest Android OS)

We will achieve this automatic number update in Android.  Only two files to edit: xml and Java.

First we will set an id, change the text and increase the text size in our default xml file:

<?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=".MainActivity">

    <TextView
       android:id="@+id/numberTV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="00"
      android:textSize="50sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Now do some changes in Java file:

1. Create an object of TextView to set our updated text referencing from the xml file.

TextView numberTextView;

2. Create an int variable to hold the updated number. If you don't assign 0, it will set 0 by default.

int number = 0;

3. Create an object of Handler which helps run code with a delay or repeatedly on the main UI thread..

Handler handler = new Handler();

4. Create an object of Runnable.
A Runnable is like a task that you tell Android to run later — either once or repeatedly. In our example, we use it to update a number every second.

Runnable runnable = new Runnable() {
    @Override
    public void run() {
        number++;
        numberTextView.setText(String.valueOf(number));
        handler.postDelayed(this, 1000);
    }
};

Inside the run method we do three things:

a) Increase the value of number
b) Set the value to our text view 
c) Run again after one second

handler.postDelayed(this, 1000);

This line starts the first run after 1 second. After that, the runnable calls itself again every second — so the number keeps increasing.

4. Now inside onCreate method we have to write just two lines of code:

numberTextView = findViewById(R.id.numberTV);
handler.postDelayed(runnable, 1000);

Here we are referencing the text view from our xml file and again calling the postDelayed method of Handler object. But this is called only once when the app starts.

5. At last we have to get out of this continuous execution when the app is not in use, so just call the onDestroy method and call the removeCallbacks method of the handler object.

@Override
protected void onDestroy() {
    super.onDestroy();
    handler.removeCallbacks(runnable);
}

Here is the complete code:

package com.prashantsj.apps.autoupdatenumber;

import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    TextView numberTextView;
    int number = 0;
    Handler handler = new Handler();
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            number++;
            numberTextView.setText(String.valueOf(number));
            handler.postDelayed(this, 1000);
        }
    };

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

        numberTextView = findViewById(R.id.numberTV);
        handler.postDelayed(runnable, 1000);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        handler.removeCallbacks(runnable);
    }
}

How to do Wireless Debugging: The Latest Simple Way!

 To do quick debugging without the traditional way of connecting cable, there is a new and simple way.

Just follow these simple steps:

Step 1: First make sure that your phone & the laptop / pc are connected to the same WIFI network. 

Step 2: In your phone go to settings and select the About phone option.

Step 3: Tap the Build Number continuously 7 times so that you see a message which says 'You are now a Developer'.

Step 4: Now To find that 'Developer Option' you just enabled, just go to Settings and select the 'System' option.

 Step 5: After selecting System, scroll down to see '{} Developer Options'. Select it.

Step 6: After selecting it, you will see an option 'Use Developer options'. Just enable it.

Step 7: Scroll down to find USB debugging. Enable this too.

Step 8: Again scroll down to find Wireless debugging and enable it.

Step 9: Select the Wireless debugging so that you will find two options for pairing: with QR code or with pairing code.

Step 10: Let's select the 'Pair device with QR code' but before that you have to first select the phone from the device list.

Step 11: Once you select your device, a QR code will be displayed which you only have to scan and you are ready to do wireless USB debugging.