Develop Reference

How can I prevent a notification from sending again if it was recently sent?

I am making an app that takes a JSON document as input and displays the information in a user-friendly way. The app will also send a push notification if certain information is outside certain parameters. The problem I am running into is that the information needs to be very up-to-date, this means the app receives a new JSON every 10 seconds. That makes the app send a push notification every 10 seconds, which is way too often. Is there a way for me to either specify a break period where the app will not send a notification if it has recently sent one? Or could I make it so if the user doesn't clear the notification, it doesn't send a new one?
I am relatively new to programming in general, and really new to Android-Studio. I have looked on the Android Developers page for NotificationManager to see if there was something there, but I was unable to find anything.
if variable1") < variable1MinValue || variable1 > variable1MaxValue||
variable2 < variable2MinValue|| variable2 > variable2MaxValue){
NotificationManager notif=
(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
Notification notify=new Notification.Builder
(getApplicationContext()).setContentTitle("ERROR: value
Error").setContentText("Please see app for more information.").
setSmallIcon(R.drawable.error_notif).setSound(soundUri).build();
notify.flags |= Notification.FLAG_AUTO_CANCEL;
notif.notify(0, notify);
I am making this app for my business, so I can't leave anything company specific in the program. If there is anything I need to clarify, please let me know!
I am hoping to be able to get it to only send the notification a few times every hour at the fastest. Ideally, maybe once every 30 minutes to an hour.

If you're on desktop, you could look at Google Guava, which has many caching utilities, including the ability to create entries with eviction times. Using that, you could add entries with an eviction of 10 minutes. Then, when a new JSON comes in, you can check if it exists in the cache. If no, send the notification, if yes, reset the eviction time for it.
You could also write your own EvictionMap. Extend ConcurrentHashMap, and in the constructor create a thread and start it. Inside the thread, you can check X seconds (sounds like every 5 seconds for you) and evict entries. The Map would require <User, long> where the long is the eviction time. You can create your own put() and get() and maybe a touch() which would reset the eviction time to System.getCurrentMillis();
(I just found a version I had used years ago. It could use some improvement with how it manages the Thread)
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
public class EvictionList<K>
{
private final ConcurrentHashMap<K, Long> evictionList = new ConcurrentHashMap<K, Long>();
private long evictionTime;
private final EvictionThread t;
public EvictionList(int evictionTimeInSeconds)
{
this.evictionTime = evictionTimeInSeconds * 1000;
t = new EvictionThread(this, evictionTime);
Thread thread = new Thread(t);
thread.start();
}
public void touch(K o)
{
evictionList.put(o, System.currentTimeMillis());
}
public void evict()
{
long current = System.currentTimeMillis();
for (Iterator<K> i=evictionList.keySet().iterator(); i.hasNext();)
{
K k = i.next();
if (current > (evictionList.get(k) + evictionTime) )
{
i.remove();
}
}
}
public void setEvictionTime(int timeInSeconds)
{
evictionTime = timeInSeconds * 1000;
t.setEvictionTime(evictionTime);
}
public Set<K> getKeys()
{
return evictionList.keySet();
}
public void stop()
{
t.shutDown();
}
#Override
protected void finalize()
{
t.shutDown();
}
private class EvictionThread implements Runnable
{
private volatile long evictionTime;
private EvictionList list;
private volatile boolean shouldRun = true;
private EvictionThread(EvictionList list, long evictionTime)
{
this.list = list;
this.evictionTime = evictionTime;
}
public void shutDown()
{
shouldRun = false;
}
public void setEvictionTime(long time)
{
evictionTime = time;
}
public void run()
{
while (shouldRun)
{
try
{
Thread.sleep(evictionTime);
}
catch (Exception ex) {}
list.evict();
}
}
}
}

How to detect upload/download transfer rate in Android?

I am working on an app which uploads a large amount of data. I want to determine the transfer rate of the upload, to show in a notification.
One post suggests using the WifiInfo which will not work for mobile data.
Another post suggests getting the network type to estimate the speed.
I'm not satisfied with the answers in these posts, so I am asking again.
I've seen apps which display the upload transfer rate, as well as some custom ROMs like Resurrection Remix.
How can I determine the transfer rate of these uploads?

It is feasible to obtain the transferred traffic amount using android.net.TrafficStats. Here is an implementation of this idea which measures the up-stream and down-stream transfer rate. You can measure the rate of mobile network by passing TrafficSpeedMeasurer.TrafficType.MOBILE to the TrafficSpeedMeasurer constructor, otherwise using TrafficSpeedMeasurer.TrafficType.ALL will result in measuring general traffic (WiFi/Mobile). Also by setting SHOW_SPEED_IN_BITS = true in MainActivity you can change the unit of speed measuring to bits per second.
MainActivity.java
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private static final boolean SHOW_SPEED_IN_BITS = false;
private TrafficSpeedMeasurer mTrafficSpeedMeasurer;
private TextView mTextView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTextView = findViewById(R.id.connection_class);
mTrafficSpeedMeasurer = new TrafficSpeedMeasurer(TrafficSpeedMeasurer.TrafficType.ALL);
mTrafficSpeedMeasurer.startMeasuring();
}
#Override
protected void onDestroy() {
super.onDestroy();
mTrafficSpeedMeasurer.stopMeasuring();
}
#Override
protected void onPause() {
super.onPause();
mTrafficSpeedMeasurer.removeListener(mStreamSpeedListener);
}
#Override
protected void onResume() {
super.onResume();
mTrafficSpeedMeasurer.registerListener(mStreamSpeedListener);
}
private ITrafficSpeedListener mStreamSpeedListener = new ITrafficSpeedListener() {
#Override
public void onTrafficSpeedMeasured(final double upStream, final double downStream) {
runOnUiThread(new Runnable() {
#Override
public void run() {
String upStreamSpeed = Utils.parseSpeed(upStream, SHOW_SPEED_IN_BITS);
String downStreamSpeed = Utils.parseSpeed(downStream, SHOW_SPEED_IN_BITS);
mTextView.setText("Up Stream Speed: " + upStreamSpeed + "\n" + "Down Stream Speed: " + downStreamSpeed);
}
});
}
};
}
TrafficSpeedMeasurer.java
import android.net.TrafficStats;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.os.SystemClock;
public class TrafficSpeedMeasurer {
private ITrafficSpeedListener mTrafficSpeedListener;
private SamplingHandler mHandler;
private TrafficType mTrafficType;
private long mLastTimeReading;
private long mPreviousUpStream = -1;
private long mPreviousDownStream = -1;
public TrafficSpeedMeasurer(TrafficType trafficType) {
mTrafficType = trafficType;
HandlerThread thread = new HandlerThread("ParseThread");
thread.start();
mHandler = new SamplingHandler(thread.getLooper());
}
public void registerListener(ITrafficSpeedListener iTrafficSpeedListener) {
mTrafficSpeedListener = iTrafficSpeedListener;
}
public void removeListener() {
mTrafficSpeedListener = null;
}
public void startMeasuring() {
mHandler.startSamplingThread();
mLastTimeReading = SystemClock.elapsedRealtime();
}
public void stopMeasuring() {
mHandler.stopSamplingThread();
finalReadTrafficStats();
}
private void readTrafficStats() {
long newBytesUpStream = (mTrafficType == TrafficType.MOBILE ? TrafficStats.getMobileTxBytes() : TrafficStats.getTotalTxBytes()) * 1024;
long newBytesDownStream = (mTrafficType == TrafficType.MOBILE ? TrafficStats.getMobileRxBytes() : TrafficStats.getTotalRxBytes()) * 1024;
long byteDiffUpStream = newBytesUpStream - mPreviousUpStream;
long byteDiffDownStream = newBytesDownStream - mPreviousDownStream;
synchronized (this) {
long currentTime = SystemClock.elapsedRealtime();
double bandwidthUpStream = 0;
double bandwidthDownStream = 0;
if (mPreviousUpStream >= 0) {
bandwidthUpStream = (byteDiffUpStream) * 1.0 / (currentTime - mLastTimeReading);
}
if (mPreviousDownStream >= 0) {
bandwidthDownStream = (byteDiffDownStream) * 1.0 / (currentTime - mLastTimeReading);
}
if (mTrafficSpeedListener != null) {
mTrafficSpeedListener.onTrafficSpeedMeasured(bandwidthUpStream, bandwidthDownStream);
}
mLastTimeReading = currentTime;
}
mPreviousDownStream = newBytesDownStream;
mPreviousUpStream = newBytesUpStream;
}
private void finalReadTrafficStats() {
readTrafficStats();
mPreviousUpStream = -1;
mPreviousDownStream = -1;
}
private class SamplingHandler extends Handler {
private static final long SAMPLE_TIME = 1000;
private static final int MSG_START = 1;
private SamplingHandler(Looper looper) {
super(looper);
}
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_START:
readTrafficStats();
sendEmptyMessageDelayed(MSG_START, SAMPLE_TIME);
break;
default:
throw new IllegalArgumentException("Unknown what=" + msg.what);
}
}
void startSamplingThread() {
sendEmptyMessage(SamplingHandler.MSG_START);
}
void stopSamplingThread() {
removeMessages(SamplingHandler.MSG_START);
}
}
public enum TrafficType {
MOBILE,
ALL
}
}
ITrafficSpeedListener.java
public interface ITrafficSpeedListener {
void onTrafficSpeedMeasured(double upStream, double downStream);
}
Utils.java
import java.util.Locale;
public class Utils {
private static final long B = 1;
private static final long KB = B * 1024;
private static final long MB = KB * 1024;
private static final long GB = MB * 1024;
public static String parseSpeed(double bytes, boolean inBits) {
double value = inBits ? bytes * 8 : bytes;
if (value < KB) {
return String.format(Locale.getDefault(), "%.1f " + (inBits ? "b" : "B") + "/s", value);
} else if (value < MB) {
return String.format(Locale.getDefault(), "%.1f K" + (inBits ? "b" : "B") + "/s", value / KB);
} else if (value < GB) {
return String.format(Locale.getDefault(), "%.1f M" + (inBits ? "b" : "B") + "/s", value / MB);
} else {
return String.format(Locale.getDefault(), "%.2f G" + (inBits ? "b" : "B") + "/s", value / GB);
}
}
}
.
Visual Result

What you're trying to determine is the transfer rate of the bytes being uploaded over your HTTP Client. Obviously, this depends on the HTTP client you're using.
There's no out-of-the-box solution which applies to all HTTP clients used on Android. The Android SDK does not provide any methods for you to determine the transfer rate of a particular upload.
Fortunately, you're using OKHttp and there is a relatively straight-forward way to do this. You're going to have to implement a custom RequestBody, and observe the bytes being written to the buffer when the request is in flight.
There's a 'recipe' for doing this on the OkHttp Github:
https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/Progress.java
You could also refer to this StackOverflow question dealing with the exact same topic:
Tracking progress of multipart file upload using OKHTTP
Another here:
OKHTTP 3 Tracking Multipart upload progress

I am talking in the context of your app since this makes it easier to capture the real time speed of your uploaded data. You don't need any extra libraries or sdk api's.
You are presumably uploading the data in chunks to the server. So
a) You know the data size of each packet
b) You know the start time before sending the packet / before sending multiple packets
c) You know the end time of xy packets by the server response e.g. status 200
With that you have all parameters to calculate the upload speed
double uploadSpeed = packet.size / (endTime - startTime) // time * 1000 to have it in seconds
EDIT:
Since you are using MultiPart from OkHttp you can monitor the amount of bytes uploaded. Tracking progress of multipart file upload using OKHTTP. You would replace packet.size with the current uploaded amount and the endTime would be an interval of xy seconds.

OpenCV capture from raspberry pi camera

How would I go about capturing an image for use in OpenCV from the standard camera module v2 plugged into a Raspberry Pi 3B? I've been trying to get high frame-rate video working, but using OpenCV's VideoCapture always gives me an empty Mat when I try to index device 0, and this and this both produced 1 frame per second or worse when I tried. I've also looked into spawning a raspivid process, but I don't see a way to get OpenCV's VideoCapture to read from the output of that process.
How would I get high FPS frame capture in Java? Is there a way I can get OpenCV to read from an OutputStream that I grab from another process?
EDIT: a simplified version of my code is below. I want to know how to populate the startRecording() function in this class
abstract class Main {
public static Mat currentCapture = null;
public static final double FOV_HEIGHT = 48.8;
public static final int WIDTH = 480;
public static final int HEIGHT = 384;
public static final int VIDEO_WIDTH = WIDTH * 2;
public static final int VIDEO_HEIGHT = HEIGHT * 2;
static {
System.loadLibrary(org.opencv.core.Core.NATIVE_LIBRARY_NAME);
}
public static void main(String[] args) {
client = new VisionClientTable("10.55.6.4", 5506);
new Thread(new VisionThread(VisionThread.Mode.VIDEO)).start();
new Thread(new VisionThread(VisionThread.Mode.TARGETING)).start();
}
private static class VisionThread implements Runnable {
private final Mode mode;
enum Mode {
VIDEO,
TARGETING
}
public VisionThread(Mode mode) {
this.mode = mode;
}
#Override
public void run() {
if (mode == Mode.TARGETING)
startTracking();
else if (mode == Mode.VIDEO)
startRecording();
}
}
public static void startTracking() {
/* this thread repeatedly captures currentCapture and processes it */
}
// this is where I need help
public static void startRecording() {
try {
VideoWriter video = new VideoWriter("/home/pi/vision/videos/video-" + Files.list(Paths.get("/home/pi/vision/captures")).count() + ".mp4", VideoWriter.fourcc('X', '2', '6', '4'), 30, new Size(VIDEO_WIDTH, VIDEO_HEIGHT), true);
VideoCapture capture = new VideoCapture(0);
capture.set(Videoio.CAP_PROP_FRAME_WIDTH, VIDEO_WIDTH);
capture.set(Videoio.CAP_PROP_FRAME_HEIGHT, VIDEO_HEIGHT);
Thread.sleep(2000);
while (true) {
long start = System.currentTimeMillis();
Mat mat = new Mat();
capture.read(mat);
if (!mat.empty()) { // mat is always empty
Mat downscaled = new Mat();
Imgproc.resize(mat, downscaled, new Size(WIDTH, HEIGHT), 0, 0, Imgproc.INTER_NEAREST);
currentCapture = downscaled;
}
video.write(mat);
long end = System.currentTimeMillis();
if (end - start < 1000 / 60)
Thread.sleep(1000 / 60 - (end - start));
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void log(String text) {
System.out.println(text);
}
}
I feel like the best way to do this might be to set raspivid to output to a file, and somehow feed the output of it into OpenCV, but I'm not sure how to do this.
EDIT 2: So far, I have tried using Runtime.getRuntime().exec() to run a raspivid command that outputs to a file, which works, but then when I try to open that file with OpenCV, capture.isOpened() remains false, even as the program repeatedly tries to open the file.

not getting much idea about your code from your question.
following may help you.
http://bigdinotech.com/tutorials/beaglebone-black-tutorials/building-opencv-on-the-beaglebone-black-or-raspberry-pi/

libgdx lag when sound.play() while collecting apple

I'am doing simple libgdx game. I have lag (game stop for 0. 5 sec) when i use sound.play()
edit this bug apear on android 4.0 on 2.3 everything is running fine.
method. I play sound by this code:
if(CollisionDetector.detect(touchArea, hoodie.getTouchArea())){
GameScreen.totalScore++;
setPosition();
System.out.println("played");
Assets.eatSound.play();
}
And i use this method to load sound:
static long waitForLoadCompleted(Sound sound,float volume) {
long id;
while ((id = sound.play(volume)) == -1) {
long t = TimeUtils.nanoTime();
while (TimeUtils.nanoTime() - t < 100000000);
}
return id;
}
What am i doing wrong? Or what can i do to fix this lag ?
edit:
I have just tried to do thread with sound.play() but it also doesn't work:
new Thread(new Runnable() {
#Override
public void run() {
// do something important here, asynchronously to the rendering thread
// post a Runnable to the rendering thread that processes the result
Gdx.app.postRunnable(new Runnable() {
#Override
public void run() {
// process the result, e.g. add it to an Array<Result> field of the ApplicationListener.
eatSound2.play();
}
});
}
}).start();
My Sound asset class looks like this but i still have lag with sound.
package com.redHoodie;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.audio.Sound;
import com.badlogic.gdx.utils.Disposable;
public class SoundEffect implements Disposable {
private static final int WaitLimit = 1000;
private static final int ThrottleMs = 100;
Sound eatSound;
Sound endSound;
public SoundEffect(){
eatSound = Gdx.audio.newSound(Gdx.files.internal("eatSound.ogg"));
endSound = Gdx.audio.newSound(Gdx.files.internal("sadend.wav"));
checkedPlay(eatSound);
}
protected long checkedPlay (Sound sound) {
return checkedPlay(sound, 1);
}
protected long checkedLoop (Sound sound) {
return checkedLoop(sound, 1);
}
protected long checkedPlay (Sound sound, float volume) {
int waitCounter = 0;
long soundId = 0;
boolean ready = false;
while (!ready && waitCounter < WaitLimit) {
soundId = sound.play(volume);
ready = (soundId != 0);
waitCounter++;
try {
Thread.sleep(ThrottleMs);
} catch (InterruptedException e) {
}
}
return soundId;
}
protected long checkedLoop (Sound sound, float volume) {
int waitCounter = 0;
long soundId = 0;
boolean ready = false;
while (!ready && waitCounter < WaitLimit) {
soundId = sound.loop(volume);
ready = (soundId != 0);
waitCounter++;
try {
Thread.sleep(ThrottleMs);
} catch (InterruptedException e) {
}
}
return soundId;
}
#Override
public void dispose() {
// TODO Auto-generated method stub
}
}

I had the same problem. It was because my .mp3 file was too short. Mine was 0.167 seconds long. I added 1.2 seconds of silence with Audacity, and it fixed the problem.

Lately I run into the same issue (except I'm using wav instead mp3 files). My app was lagging when I play many (like 10 or 20) sounds at the same time (same render method). "Solved" this by playing only 1 sound at the time. Generally it's hard to distinct many sounds at the same time. Also on desktop it works fine, but problem appears on android (9 or 8).

If someone still facing this issue as me there is the alternative solution with one limitation: no option to use sound id.
You can change default LibGDX behavior and use AsynchronousAndroidAudio by overriding this method in your AndroidLauncher class:
#Override
public AndroidAudio createAudio(Context context, AndroidApplicationConfiguration config) {
return new AsynchronousAndroidAudio(context, config);
}
See the official documentation for more info and also the pull request
Also, if for any reasons you need sound id you can take this implementation as an example and find a workaround for your project.
Fix is available starting from LibGDX 1.9.12

java sound, fadeIn effect, using FloatControl

Im trying to implement fade in effect to my mp3 player.
I´m using
FloatControl volumeControl = (FloatControl) line.getControl(FloatControl.Type.MASTER_GAIN);
because FloatControl.Type.VOLUME throws an exception(Unavaliable Control) I dont know why.
I need some help with the algorithm, because its not working ok.
Heres the code:
public class FloatControlFader
{
public static void fadeIn(final FloatControl control, final float from,
final float to, final int seconds)
{
final float vps = ((to-from) / (seconds*10));//Volume incrased/100millisecond
control.setValue(from);
Thread t = new Thread(new Runnable(){
public void run() {
for(int i=0; i < seconds*10; i++)
{
try
{
Thread.sleep(100);
}
catch (InterruptedException ex)
{
}
System.out.println(control.getValue()); //for DEBUG
control.setValue(control.getValue() + vps);
}
}
});
t.start();
}
}
Would appreciate any help, thanks!

Remember the human ear does not hear linearly so increasing by a steady X vps is not going to sound like a smooth fade. You need to put a log function in there. Then you need to map the linear increases to log values. This is of course all assuming the volume control units are not in decibels. If you're increasing by db then you're fine.