Example of code to turn on/off a android flashlight in a particular sequence and speed

FlashLightBlinkerFragment.java

package esmaltec.etalk;

import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.content.ContextCompat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.ToggleButton;

import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

import static android.content.Context.CAMERA_SERVICE;
import static java.lang.Integer.MIN_VALUE;

/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment {

    private View view;
    private SeekBar seekBar;
    private View flashView;
    private ToggleButton toggleButtonFlashHardware;
    private ToggleButton toggleButtonFlashView;
    private EditText textViewSeekBarValue;
    private Camera mCamera;
    private Camera.Parameters mParams;
    private CameraManager mManager;
    private EditText editTextCodigo;
    private Thread mThread;


    public MainActivityFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        view = inflater.inflate(R.layout.fragment_main, container, false);

        textViewSeekBarValue = (EditText) view.findViewById(R.id.textViewSeekBarValue);
        editTextCodigo = (EditText) view.findViewById(R.id.editTextCodigo);
        seekBar = (SeekBar) view.findViewById(R.id.seekBar);
        flashView = (View) view.findViewById(R.id.flashView);
        toggleButtonFlashHardware = (ToggleButton) view.findViewById(R.id.toggleButtonFlashHardware);
        toggleButtonFlashView = (ToggleButton) view.findViewById(R.id.toggleButtonFlashView);

        if (seekBar.getProgress() < MIN_VALUE) {
            seekBar.setProgress(1);
        }

        seekBar.setProgress(100);
        textViewSeekBarValue.setText("100");
        seekBar.setMax(1000);
        turnOffFlashView();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            mManager = (CameraManager) getActivity().getSystemService(CAMERA_SERVICE);
        } else {
            mCamera = Camera.open();
            mParams = mCamera.getParameters();
        }


        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {

                textViewSeekBarValue.setText(String.valueOf(seekBar.getProgress()));

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });

        toggleButtonFlashView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {


                if (toggleButtonFlashView.isChecked()) {

                    mThread = new Thread(new Runnable() {
                        @Override
                        public void run() {
                            try {

                                Thread.sleep(3000);

                                for (int i = 0; i < editTextCodigo.getText().length(); i++) {

                                    if (editTextCodigo.getText().charAt(i) == '0') {

                                        getActivity().runOnUiThread(new Runnable() {
                                            @Override
                                            public void run() {
                                                turnOffFlashView();
                                            }
                                        });

                                    } else {
                                        getActivity().runOnUiThread(new Runnable() {
                                            @Override
                                            public void run() {
                                                turnOnFlashView();
                                            }
                                        });
                                    }


                                    if (i == editTextCodigo.getText().length()-1) {

                                        getActivity().runOnUiThread(new Runnable() {
                                            @Override
                                            public void run() {
                                                toggleButtonFlashView.setChecked(false);
                                                turnOffFlashView();
                                            }
                                        });
                                        return;

                                    }

                                    Thread.sleep(Integer.valueOf(textViewSeekBarValue.getText().toString()));

                                }



                            } catch (Exception e) {
                                e.getLocalizedMessage();
                            }
                        }
                    });

                    mThread.start();


                } else {

                    mThread.interrupt();

                    turnOffFlashView();

                }


            }
        });


        toggleButtonFlashHardware.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (toggleButtonFlashHardware.isChecked()) {

                    long blinkDelay = Integer.valueOf(textViewSeekBarValue.getText().toString()); //Delay in ms

                    for (int i = 0; i < editTextCodigo.getText().length(); i++) {

                        if (editTextCodigo.getText().charAt(i) == '0') {
                            turnOffCameraFlash();
                        } else {
                            turnOnCameraFlash();
                        }
                        try {
                            Thread.sleep(blinkDelay);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                        if (i == editTextCodigo.getText().length() - 1)
                            toggleButtonFlashHardware.setChecked(false);

                        if (!toggleButtonFlashHardware.isChecked()) {
                            break;
                        }

                    }

                } else {

                    turnOffCameraFlash();

                }


            }
        });


        return view;
    }

    private void turnOnFlashView() {
        flashView.setBackgroundColor(ContextCompat.getColor(getContext(), android.R.color.white));
    }

    private void turnOffFlashView() {
        flashView.setBackgroundColor(ContextCompat.getColor(getContext(), android.R.color.black));
    }

    private void turnOnCameraFlash() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

            try {

                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    mManager.setTorchMode(getCameraInstanceV2(), true);
                }

            } catch (CameraAccessException e) {
                e.printStackTrace();
            }

        } else {

            mParams.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
            mCamera.setParameters(mParams);
            mCamera.startPreview();

        }

    }

    private void turnOffCameraFlash() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

            try {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    mManager.setTorchMode(getCameraInstanceV2(), false);
                }
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }

        } else {

            mParams.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
            mCamera.setParameters(mParams);
            mCamera.stopPreview();

        }

    }

    /**
     * Check if this device has a camera
     */
    private boolean checkCameraFlashHardware() {
        if (getActivity().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH)) {
            // this device has a camera flash
            return true;
        } else {
            // no camera flash on this device
            return false;
        }
    }

    /**
     * A safe way to get an instance of the android.hardware.camera2 object.
     */
    public String getCameraInstanceV2() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

            try {

                for (String cameraId : mManager.getCameraIdList()) {

                    CameraCharacteristics chars = mManager.getCameraCharacteristics(cameraId);

                    if (chars.get(CameraCharacteristics.FLASH_INFO_AVAILABLE)) {

                        // Retorna a primeira camera com flash disponivel
                        return cameraId;
                    }


                }

            } catch (CameraAccessException e) {
                e.printStackTrace();
            }

        }

        return "-1";

    }

    /**
     * A safe way to get an instance of the android.hardware.camera object.
     */

    public static Camera getCameraInstanceV1() {
        Camera c = null;
        try {
            c = Camera.open(); // attempt to get a Camera instance
        } catch (Exception e) {
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }

    @Override
    public void onPause() {
        super.onPause();
        releaseCamera();              // release the camera immediately on pause event
    }

    private void releaseCamera() {
        if (mCamera != null) {
            mCamera.release();        // release the camera for other applications
            mCamera = null;
        }
    }

}

fragment_main.xml

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

    <View
        android:id="@+id/flashView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        android:layout_above="@+id/textViewSeekBarValue" />

    <EditText
        android:id="@+id/textViewSeekBarValue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0.0"
        android:inputType="numberDecimal"
        android:layout_margin="10dp"
        android:textAlignment="center"
        android:layout_above="@+id/seekBar"
        />

    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="30dp"
        android:layout_above="@+id/editTextCodigo"
        />

    <EditText
        android:id="@+id/editTextCodigo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:text="01010101010101010101010101010100110011001100110011000111000114000111000111000111000111000111000111000000111111000000111111000000111111000000111111"
        android:layout_above="@+id/linearLayoutBottom"
        />

    <LinearLayout
        android:id="@+id/linearLayoutBottom"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="40dp"
        android:layout_alignParentBottom="true"
        android:gravity="center"
        android:orientation="horizontal">


        <ToggleButton
            android:id="@+id/toggleButtonFlashView"
            android:layout_width="match_parent"
            android:layout_height="80dp"
            android:textOn="ON"
            android:textOff="OFF"
            android:text="Tela"
            />

    </LinearLayout>

</RelativeLayout>