How to open flashLight of android phone programmatically

declare these variables in the activity

 private boolean isLighOn = false; // to check tht flash is on or off
 boolean flashAvailable=false;
  int cameraID=0  /*cameraId with 0 represents back camera**/

firstly we have to check if phone supports flash light or not.

 Camera myCamera=getCameraInstance(cameraID);
  final Parameters parameter = myCamera.getParameters();

if (packageManager.hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH))
     {
      flashAvailable=true;
     }
 else
     {
       flashAvailable=false;
     }

code snippet to on-off the falsh

    Button button = (Button) findViewById(R.id.buttonFlashlight); 
button.setOnClickListener(new OnClickListener() {
 @Override public void onClick(View arg0) { 
if(flashAvailable){
 if (isLighOn) 
   {
     p.setFlashMode(Parameters.FLASH_MODE_OFF);
     try {
          myCamera.setParameters(p); 
           }
      catch(RuntimeException ex) 
         {
          } 
      myCamera.startPreview(); 
      isLighOn = false; 
    } 
  else
  {
     p.setFlashMode(Parameters.FLASH_MODE_TORCH);
       try { 
           myCamera.setParameters(p); 
           } catch(RuntimeException ex) 
          {
           } myCamera.startPreview();
       isLighOn = true; 
     } 
  } 
else
 { 
Toast.makeText(getApplicationContext(),"Your Phone does not have flash", Toast.LENGTH_SHORT).show();
 } 
} 
});