how to get input from barcode reader in java 9: Threads in Java

Create PDF-417 2d barcode in Java 9: Threads

9: Threads
Recognize PDF-417 2d Barcode In Java
Using Barcode Control SDK for Java Control to generate, create, read, scan barcode image in Java applications.
Encoding PDF417 In Java
Using Barcode encoder for Java Control to generate, create PDF 417 image in Java applications.
TWO-MINUTE DRILL
PDF 417 Recognizer In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
Bar Code Drawer In Java
Using Barcode maker for Java Control to generate, create barcode image in Java applications.
Here are some of the key points from each certification objective in 9. Photocopy it and sleep with it under your pillow for complete absorption.
Bar Code Recognizer In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
PDF 417 Drawer In Visual C#
Using Barcode maker for VS .NET Control to generate, create PDF-417 2d barcode image in .NET applications.
Creating, Instantiating, and Starting New Threads Threads can be created by extending Thread and overriding the public
PDF417 Drawer In VS .NET
Using Barcode generation for ASP.NET Control to generate, create PDF-417 2d barcode image in ASP.NET applications.
PDF417 Printer In .NET
Using Barcode maker for VS .NET Control to generate, create PDF-417 2d barcode image in VS .NET applications.
void run() method.
Draw PDF-417 2d Barcode In Visual Basic .NET
Using Barcode creation for .NET framework Control to generate, create PDF 417 image in .NET framework applications.
EAN13 Drawer In Java
Using Barcode drawer for Java Control to generate, create EAN13 image in Java applications.
Thread objects can also be created by calling the Thread constructor that
Matrix Barcode Generator In Java
Using Barcode drawer for Java Control to generate, create 2D Barcode image in Java applications.
EAN / UCC - 14 Generation In Java
Using Barcode creator for Java Control to generate, create UCC.EAN - 128 image in Java applications.
takes a Runnable argument. The Runnable object is said to be the target of the thread.
UCC - 14 Printer In Java
Using Barcode encoder for Java Control to generate, create DUN - 14 image in Java applications.
Make Bar Code In C#.NET
Using Barcode creator for .NET framework Control to generate, create barcode image in VS .NET applications.
You can call start() on a Thread object only once. If start() is called
Code 128 Maker In Objective-C
Using Barcode creator for iPad Control to generate, create Code 128 Code Set A image in iPad applications.
Code 39 Scanner In Visual Basic .NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
more than once on a Thread object, it will throw a RuntimeException.
Paint Code 128A In None
Using Barcode printer for Excel Control to generate, create Code 128C image in Excel applications.
Decoding Bar Code In Java
Using Barcode Control SDK for Java Control to generate, create, read, scan barcode image in Java applications.
It is legal to create many Thread objects using the same Runnable object as
Generate GTIN - 13 In Objective-C
Using Barcode maker for iPhone Control to generate, create UPC - 13 image in iPhone applications.
Making Code128 In None
Using Barcode drawer for Software Control to generate, create Code-128 image in Software applications.
the target.
When a Thread object is created, it does not become a thread of execution until
its start() method is invoked. When a Thread object exists but hasn t been started, it is in the new state and is not considered alive.
Transitioning Between Thread States Once a new thread is started, it will always enter the runnable state. The thread scheduler can move a thread back and forth between the runnable
state and the running state.
Only one thread can be running at a time, although many threads may be in
the runnable state.
There is no guarantee that the order in which threads were started determines
the order in which they ll run.
There s no guarantee that threads will take turns in any fair way. It s up to
the thread scheduler, as determined by the particular virtual machine implementation. If you want a guarantee that your threads will take turns regardless of the underlying JVM, you should can use the sleep() method. This prevents one thread from hogging the running process while another thread starves.
Two-Minute Drill
A running thread may enter a blocked/waiting state by a wait(), sleep(),
or join() call.
A running thread may enter a blocked/waiting state because it can t acquire
the lock for a synchronized block of code.
When the sleep or wait is over, or an object s lock becomes available, the
thread can only reenter the runnable state. It will go directly from waiting to running (well, for all practical purposes anyway).
A dead thread cannot be started again. Sleep, Yield, and Join Sleeping is used to delay execution for a period of time, and no locks are
released when a thread goes to sleep.
A sleeping thread is guaranteed to sleep for at least the time specified in the
argument to the sleep method (unless it s interrupted), but there is no guarantee as to when the newly awakened thread will actually return to running.
The sleep() method is a static method that sleeps the currently executing
thread. One thread cannot tell another thread to sleep.
The setPriority() method is used on Thread objects to give threads a
priority of between 1 (low) and 10 (high), although priorities are not guaranteed, and not all JVMs use a priority range of 1-10.
If not explicitly set, a thread s priority will be the same priority as the thread
that created this thread (in other words, the thread executing the code that creates the new thread).
The yield() method may cause a running thread to back out if there are
runnable threads of the same priority. There is no guarantee that this will happen, and there is no guarantee that when the thread backs out it will be different thread selected to run. A thread might yield and then immediately reenter the running state.
The closest thing to a guarantee is that at any given time, when a thread is
running it will usually not have a lower priority than any thread in the runnable state. If a low-priority thread is running when a high-priority thread enters runnable, the JVM will preempt the running low-priority thread and put the high-priority thread in.
9: Threads
When one thread calls the join() method of another thread, the currently
running thread will wait until the thread it joins with has completed. Think of the join() method as saying, Hey thread, I want to join on to the end of you. Let me know when you re done, so I can enter the runnable state.
Concurrent Access Problems and Synchronized Threads Synchronized methods prevent more than one thread from accessing an object s
critical method code.
You can use the synchronized keyword as a method modifier, or to start
a synchronized block of code.
To synchronize a block of code (in other words, a scope smaller than the
whole method), you must specify an argument that is the object whose lock you want to synchronize on.
While only one thread can be accessing synchronized code of a particular
instance, multiple threads can still access the same object s unsynchronized code.
When an object goes to sleep, it takes its locks with it. Static methods can be synchronized, using the lock from the java.lang.Class
instance representing that class.
Communicating with Objects by Waiting and Notifying The wait() method lets a thread say, there s nothing for me to do here,
so put me in your waiting pool and notify me when something happens that I care about. Basically, a wait() call means wait me in your pool, or add me to your waiting list.
The notify() method is used to send a signal to one and only one of the
threads that are waiting in that same object s waiting pool.
The method notifyAll() works in the same way as notify(), only it
sends the signal to all of the threads waiting on the object.
All three methods wait()/notify()/notifyAll() must be called
from within a synchronized context! A thread invokes wait()/notify() on a particular object, and the thread must currently hold the lock on that object.
Two-Minute Drill
Deadlocked Threads Deadlocking is when thread execution grinds to a halt because the code is
waiting for locks to be removed from objects.
Deadlocking can occur when a locked object attempts to access another locked
object that is trying to access the first locked object. In other words, both threads are waiting for each other s locks to be released; therefore, the locks will never be released!
Deadlocking is bad. Don t do it.
9: Threads
SELF TEST
The following questions will help you measure your understanding of the material presented in this chapter. Read all of the choices carefully, as there may be more than one correct answer. Choose all correct answers for each question. Stay focused. If you have a rough time with these at first, don t beat yourself up. Be positive. Repeat nice affirmations to yourself like, I am smart enough to understand threads. I can do this. and OK, so that other guy knows threads better than I do, but I bet he can t <insert something you are good at> like me.
1. Given the following,
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. class MyThread extends Thread { public static void main(String [] args) { MyThread t = new MyThread(); t.run(); } public void run() { for(int i=1;i<3;++i) { System.out.print(i + ".."); } } }
Copyright © OnBarcode.com . All rights reserved.