I am building a download manager in javafx
I have added function to download button which initialises new task.More than one download is also being executed properly.
But I need to add pause and resume function. Please tell how to implement it using executor. Through execute function of Executors, task is being started but how do i pause & then resume it??
Below I am showing relevant portions of my code. Please tell if you need more details. thanks.
Main class
public class Controller implements Initializable {
public Button addDownloadButton;
public Button pauseResumeButton;
public TextField urlTextBox;
public TableView<DownloadEntry> downloadsTable;
ExecutorService executor;
#Override
public void initialize(URL location, ResourceBundle resources) {
// here tableview and table columns are initialised and cellValueFactory is set
executor = Executors.newFixedThreadPool(4);
}
public void addDownloadButtonClicked() {
DownloadEntry task = new DownloadEntry(new URL(urlTextBox.getText()));
downloadsTable.getItems().add(task);
executor.execute(task);
}
public void pauseResumeButtonClicked() {
//CODE FOR PAUSE AND RESUME
}
}
DownloadEntry.java
public class DownloadEntry extends Task<Void> {
public URL url;
public int downloaded;
final int MAX_BUFFER_SIZE=50*1024;
private String status;
//Constructor
public DownloadEntry(URL ur) throws Exception{
url = ur;
//other variables are initialised here
this.updateMessage("Downloading");
}
#Override
protected Void call() {
file = new RandomAccessFile(filename, "rw");
file.seek(downloaded);
stream = con.getInputStream();
while (status.equals("Downloading")) {
byte buffer=new byte[MAX_BUFFER_SIZE];
int c=stream.read(buffer);
if (c==-1){
break;
}
file.write(buffer,0,c);
downloaded += c;
status = "Downloading";
}
if (status.equals("Downloading")) {
status = "Complete";
updateMessage("Complete");
}
return null;
}
}
You may be interested in Concurrency in JavaFX.
I guess you should also have a look at pattern Observer.
By the way I think you should not use constant string as a status ("Downloading", etc), creating an enum would be a better approach.
In your loop, around the read/write part, there should be a synchronization mechanism, controlled by your pause/resume buttons (see the two links).
Related
I have an external dll written in C# and I studied from the assemblies documentation that it writes its debug messages to the Console using Console.WriteLine.
this DLL writes to console during my interaction with the UI of the Application, so i don't make DLL calls directly, but i would capture all console output , so i think i got to intialize in form load , then get that captured text later.
I would like to redirect all the output to a string variable.
I tried Console.SetOut, but its use to redirect to string is not easy.
As it seems like you want to catch the Console output in realtime, I figured out that you might create your own TextWriter implementation that fires an event whenever a Write or WriteLine happens on the Console.
The writer looks like this:
public class ConsoleWriterEventArgs : EventArgs
{
public string Value { get; private set; }
public ConsoleWriterEventArgs(string value)
{
Value = value;
}
}
public class ConsoleWriter : TextWriter
{
public override Encoding Encoding { get { return Encoding.UTF8; } }
public override void Write(string value)
{
if (WriteEvent != null) WriteEvent(this, new ConsoleWriterEventArgs(value));
base.Write(value);
}
public override void WriteLine(string value)
{
if (WriteLineEvent != null) WriteLineEvent(this, new ConsoleWriterEventArgs(value));
base.WriteLine(value);
}
public event EventHandler<ConsoleWriterEventArgs> WriteEvent;
public event EventHandler<ConsoleWriterEventArgs> WriteLineEvent;
}
If it's a WinForm app, you can setup the writer and consume its events in the Program.cs like this:
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
using (var consoleWriter = new ConsoleWriter())
{
consoleWriter.WriteEvent += consoleWriter_WriteEvent;
consoleWriter.WriteLineEvent += consoleWriter_WriteLineEvent;
Console.SetOut(consoleWriter);
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
static void consoleWriter_WriteLineEvent(object sender, Program.ConsoleWriterEventArgs e)
{
MessageBox.Show(e.Value, "WriteLine");
}
static void consoleWriter_WriteEvent(object sender, Program.ConsoleWriterEventArgs e)
{
MessageBox.Show(e.Value, "Write");
}
It basically amounts to the following:
var originalConsoleOut = Console.Out; // preserve the original stream
using(var writer = new StringWriter())
{
Console.SetOut(writer);
Console.WriteLine("some stuff"); // or make your DLL calls :)
writer.Flush(); // when you're done, make sure everything is written out
var myString = writer.GetStringBuilder().ToString();
}
Console.SetOut(originalConsoleOut); // restore Console.Out
So in your case you'd set this up before making calls to your third-party DLL.
You can also call SetOut with Console.OpenStandardOutput, this will restore the original output stream:
Console.SetOut(new StreamWriter(Console.OpenStandardOutput()));
Or you can wrap it up in a helper method that takes some code as an argument run it and returns the string that was printed. Notice how we gracefully handle exceptions.
public string RunCodeReturnConsoleOut(Action code)
{
string result;
var originalConsoleOut = Console.Out;
try
{
using (var writer = new StringWriter())
{
Console.SetOut(writer);
code();
writer.Flush();
result = writer.GetStringBuilder().ToString();
}
return result;
}
finally
{
Console.SetOut(originalConsoleOut);
}
}
Using solutions proposed by #Adam Lear and #Carlo V. Dango I created a helper class:
public sealed class RedirectConsole : IDisposable
{
private readonly Action<string> logFunction;
private readonly TextWriter oldOut = Console.Out;
private readonly StringWriter sw = new StringWriter();
public RedirectConsole(Action<string> logFunction)
{
this.logFunction = logFunction;
Console.SetOut(sw);
}
public void Dispose()
{
Console.SetOut(oldOut);
sw.Flush();
logFunction(sw.ToString());
sw.Dispose();
}
}
which can be used in the following way:
public static void MyWrite(string str)
{
// print console output to Log/Socket/File
}
public static void Main()
{
using(var r = new RedirectConsole(MyWrite)) {
Console.WriteLine("Message 1");
Console.WriteLine("Message 2");
}
// After the using section is finished,
// MyWrite will be called once with a string containing all messages,
// which has been written during the using section,
// separated by new line characters
}
I have a JavaFX application which instantiates several Task objects.
Currently, my implementation (see below) calls the behavior runFactory() which performs computation under a Task object. Parallel to this, nextFunction() is invoked. Is there a way to have nextFunction() "wait" until the prior Task is complete?
I understand thread.join() waits until the running thread is complete, but with GUIs, there are additional layers of complexity due to the event dispatch thread.
As a matter of fact, adding thread.join() to the end of the code-segment below only ceases UI interaction.
If there are any suggestions how to make nextFunction wait until its prior function, runFactory is complete, I'd be very appreciative.
Thanks,
// High-level class to run the Knuth-Morris-Pratt algorithm.
public class AlignmentFactory {
public void perform() {
KnuthMorrisPrattFactory factory = new KnuthMorrisPrattFactory();
factory.runFactory(); // nextFunction invoked w/out runFactory finishing.
// Code to run once runFactory() is complete.
nextFunction() // also invokes a Task.
...
}
}
// Implementation of Knuth-Morris-Pratt given a list of words and a sub-string.
public class KnuthMorrisPratt {
public void runFactory() throws InterruptedException {
Thread thread = null;
Task<Void> task = new Task<Void>() {
#Override public Void call() throws InterruptedException {
for (InputSequence seq: getSequences) {
KnuthMorrisPratt kmp = new KnuthMorrisPratt(seq, substring);
kmp.align();
}
return null;
}
};
thread = new Thread(task);
thread.setDaemon(true);
thread.start();
}
When using Tasks you need to use setOnSucceeded and possibly setOnFailed to create a logic flow in your program, I propose that you also make runFactory() return the task rather than running it:
// Implementation of Knuth-Morris-Pratt given a list of words and a sub-string.
public class KnuthMorrisPratt {
public Task<Void> runFactory() throws InterruptedException {
return new Task<Void>() {
#Override public Void call() throws InterruptedException {
for (InputSequence seq: getSequences) {
KnuthMorrisPratt kmp = new KnuthMorrisPratt(seq, substring);
kmp.align();
}
return null;
}
};
}
// High-level class to run the Knuth-Morris-Pratt algorithm.
public class AlignmentFactory {
public void perform() {
KnuthMorrisPrattFactory factory = new KnuthMorrisPrattFactory();
Task<Void> runFactoryTask = factory.runFactory();
runFactoryTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
#Override
public void handle(WorkerStateEvent t)
{
// Code to run once runFactory() is completed **successfully**
nextFunction() // also invokes a Task.
}
});
runFactoryTask.setOnFailed(new EventHandler<WorkerStateEvent>() {
#Override
public void handle(WorkerStateEvent t)
{
// Code to run once runFactory() **fails**
}
});
new Thread(runFactoryTask).start();
}
}
I am trying to silence an incoming call and prevent the BlackBerry device from ringing. I tried Alert.setVolume(0) and some EventInjector keys but this didn't work.
So how to silence an incoming call?
I was puzzled by your question and decided to take up the challenge. I tried different thing including
Playing a "silence" audio file hoping to overlap the device's ringing or occupy the media player
Hacking the phone screen via UiApplication.getUiApplication().getActiveScreen()
Injecting keyboard events
Eventually, injecting VOLUME UP key (VOLUME DOWN key works as well) event worked for me and muted the device ringing on incoming call. The drawback with this approach is that sometimes the device did ring for a fraction of second before muting.
import net.rim.blackberry.api.phone.AbstractPhoneListener;
import net.rim.blackberry.api.phone.Phone;
import net.rim.device.api.system.Application;
import net.rim.device.api.system.EventInjector;
import net.rim.device.api.ui.Keypad;
class Muter extends AbstractPhoneListener {
public void callIncoming(int callId) {
Thread muterThread = new Thread(new Runnable() {
public void run() {
EventInjector.invokeEvent(new EventInjector.KeyCodeEvent(EventInjector.KeyCodeEvent.KEY_DOWN, (char) Keypad.KEY_VOLUME_UP, 0));
EventInjector.invokeEvent(new EventInjector.KeyCodeEvent(EventInjector.KeyCodeEvent.KEY_UP, (char) Keypad.KEY_VOLUME_UP, 0));
}
});
muterThread.setPriority(Thread.MAX_PRIORITY);
muterThread.start();
}
}
public class MuterApp extends Application {
public static void main(String[] args){
Phone.addPhoneListener(new Muter());
new MyApp().enterEventDispatcher();
}
}
The following also works (replace Muter thread in callIncoming() method with the following code).
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
EventInjector.invokeEvent(new EventInjector.KeyCodeEvent(EventInjector.KeyCodeEvent.KEY_DOWN, (char) Keypad.KEY_VOLUME_UP, 0));
EventInjector.invokeEvent(new EventInjector.KeyCodeEvent(EventInjector.KeyCodeEvent.KEY_UP, (char) Keypad.KEY_VOLUME_UP, 0));
}
});
You won't be able to disable the sound programmatically (found a couple other sources that said the same thing). The best workaround people have seemed to come up with was to use the EventInjector to change the phone's sound profile to silent.
Some Blackberry phones have a mute key. You may try the following idea:
public void callIncoming(int callId) {
if (KeyPad.hasMuteKey()) {
/* Inject KEY_SPEAKERPHONE event */
}
else {
/* Inject KEY_VOLUME_DOWN event N times, so that you get the mute effect */
}
}
i am quite new to all this...but i thought i might as well put in my 2 cents worth...
i have been trying to find ways to programatically change the profile settings...
i have found that, while we cannot(yet) change the profile settings, we can change the setting that we are using( change the profile thats in use, i think)- this is something i came across searching for info-though i should give credit to alishaik786 for the code.
public final class LoadingScreen extends MainScreen implements FieldChangeListener
{
public LoadingScreen()
{
createGUI();
}
private void createGUI()
{
try
{
ApplicationManager.getApplicationManager().launch("net_rim_bb_profiles_app");
}
catch (Exception e)
{
//Exception
}
}
public void fieldChanged(Field field, int context)
{
}
}
I make and display an clock count down with this code
LabelField time;
long mille=0;
Timer timer=null;TimerTask task=null;
public Timerscreen() {
mille=1000*60*1;
time=new LabelField();
add(time);
timer=new Timer();
task=new TimerTask() {
public void run() {
synchronized (UiApplication.getEventLock()) {
if(mille!=0){
SimpleDateFormat date=new SimpleDateFormat("mm:ss") ;
System.out.println("================="+date.formatLocal(mille)+"====================="+Thread.activeCount());
time.setText(date.formatLocal(mille));
mille=mille-1000;
}else{
time.setText("00:00");
mille=1000*60*1;
timer.cancel();
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.inform("Time expaired");
}
});
}
}
}
};
timer.schedule(task,0, 1000);
And when I push a new screen , I want to this clock still display and count down.
How can I do that ?
It is not possible to add a single ui field or manager into two managers or screens.. every ui field or manager must have at most one parent (screen or manager).
So if you need a LabelField which will hold and show time on different screens, then you only need to implement some sort of listener which will listen for the time changes.. and for every changes you have to update the screen and the LabelField with the new value. You have already implemented a TimerTask which will provide you updated data.
[Edited - added later]
you can check the following codes, not tested but something like this will solve your problem...
class MyTimerUtil {
TimerListener listener = null;
public MyTimerUtil() {
}
public void setTimerListener(TimerListener listener) {
this.listener = listener;
}
public void startTimer() {
final int interval = 1000;
Timer timer = new Timer();
TimerTask task = new TimerTask() {
public void run() {
// add your codes..
// notify others
if (listener != null) {
listener.timeChanged();
}
}
};
timer.schedule(task, 0, interval);
}
}
interface TimerListener {
public void timeChanged();
}
class ScreeA extends MainScreen implements TimerListener {
public void timeChanged() {
// add Codes here on time changed event
}
}
in the above snippet, you can implement TimerListener interface in any screen instance and can get update on every time changed event by the MyTimerUtil class. For that, you have to set an instance of ScreeA (which implements TimerListener) via setTimerListener() of the MyTimerUtil class.
Also need to start the timer by calling startTimer() method.
I created app which user can start from menu and from icon. I do not use GlobalEventListener in my app, just register ApplicationMenuitem. And now I am getting error: previous instance still active when launch my app.
Steps to reproduce not so trivial:
launch app from icon
do not close it, just switch to another app
launch app from icon again
I founded article in blackberry's forum about it , but I can't find solution where I should remove my ApplicationMenuItem: it added on phone boot and should show all the time.
My code:
public class Jingu extends UiApplication {
public static void main(String[] args) {
ApplicationManager app = ApplicationManager.getApplicationManager();
boolean keepGoing = true;
while (keepGoing) {
if (app.inStartup()) {
try {
Thread.sleep(1000);
} catch (Exception e) {}
} else {
keepGoing = false;
}
}
Jingu theApp = new Jingu();
theApp.initMenuItem();
theApp.showMainScreen();
theApp.enterEventDispatcher();
}
public Jingu() {
}
public void showMainScreen() {
showScreen(new JinguMainScreen(this));
}
public void initMenuItem() {
// Create menu item
Object o = RuntimeStore.getRuntimeStore().get(JinguMenuItem.MY_MENU_ID);
// register only if not done already.
if (o == null) {
new JinguMenuItem(this).registerInstance();
}
}
public void showScreen(Screen aScreen) {
synchronized (Application.getEventLock()) {
try {
UiApplication.getUiApplication().popScreen(aScreen);
} catch (Exception e) {
}
UiApplication.getUiApplication().pushScreen(aScreen);
}
}
}
public class JinguMenuItem extends ApplicationMenuItem {
public static final long MY_MENU_ID = 0xb9739d5240d5943dL;
private final Jingu jingu;
public JinguMenuItem(Jingu jingu) {
super(0x350100);
this.jingu = jingu;
}
public void registerInstance() {
Object menuItem = RuntimeStore.getRuntimeStore().remove(MY_MENU_ID);
if (menuItem == null) {
ApplicationMenuItemRepository amir = ApplicationMenuItemRepository.getInstance();
amir.addMenuItem(ApplicationMenuItemRepository.MENUITEM_SYSTEM, this);
RuntimeStore.getRuntimeStore().put(MY_MENU_ID, this);
}
}
public Object run(Object context) {
jingu.setDefaultFont(Font.getDefault());
jingu.setMainApp(false);
jingu.setBbmEditField(null);
jingu.showMainScreen();
return context;
}
public String toString() {
return "My Menu";
}
}
plz advice where I should delete ApplicationMenuItem in my app?
my regards,
Vadim
If you are registering an ApplicationMenuItem from your application, as a user I would consider it bad style for your application to remove and exit, even if RIM provided a way to do this. You may want to separate your application into two parts. One provides the minimal support for responding to the ApplicationMenuItem selection, that starts automatically and runs in the background. The other has all the rest and can run and exit as needed.
My solution for this situation is:
create alternative entry point and run it on app load
register menu in it
do not use runtimeStore