Can we restart a dead thread in Java?
Once a thread enters dead state it cannot be restarted
.
Which method restarts a dead thread in Java?
Since a Thread can not be restarted you have to create a new Thread everytime. A better practice is to separate the code to run in a thread from a Thread ‘s lifecycle by using the Runnable interface. Just
extract the run method in a class that implements Runnable
. Then you can easily restart it.
What happens if we start a dead thread?
Once the thread completes its run() method and dead, it cannot be brought back to thread of execution or even to runnable state. Invoking start() method on a dead thread
causes runtime exception
.
How do I start a thread again?
No.
After starting a thread, it can never be started again
. If you does so, an IllegalThreadStateException is thrown. In such case, thread will run once but for second time, it will throw exception.
How do I stop and restart a thread?
Once a thread stops you cannot restart it. However, there is nothing stopping you from creating and starting a new thread. Option 1:
Create a new thread rather than trying to restart
. Option 2: Instead of letting the thread stop, have it wait and then when it receives notification you can allow it to do work again.
Can we start a dead thread again?
Once a thread enters dead state it cannot be restarted
.
What is the difference between run () and start () methods in threads?
start method of thread class is implemented as when it is called a new Thread is created and code inside run() method is executed in that new Thread
. While if run method is executed directly than no new Thread is created and code inside run() will execute on current Thread and no multi-threading will take place.
Why can’t we start a thread twice in Java?
according to thread life cycle,
once thread is ‘dead’ you can not restart it
. You only can start new thread invoking start() method. Thread can be bought to Running state from Runnable state not from Dead state.
Can we call run method twice?
The run method is called twice
. One call is by calling start() in the MyRunnable constructor; this is executed in the separate thread. That prints “MyRunnable”. However, you also call run directly in main , which is executed in the main thread.
Can you call start method twice in Java?
From the Java API Specification for the Thread. start method:
It is never legal to start a thread more than once
. In particular, a thread may not be restarted once it has completed execution.
How do you start a new thread in Java?
- public void run( )
- public class MyClass implements Runnable { public void run(){ System. out. println(“MyClass running”); …
- Thread t1 = new Thread(new MyClass ()); t1. start();
- public class MyClass extends Thread { public void run(){ System. out. …
- MyClass t1 = new MyClass (); T1. start();
What is the difference between notify () and notifyAll ()?
In case of multiThreading notify() method sends the notification to only one thread among the multiple waiting threads which are waiting for lock. While notifyAll() methods in the same context sends the notification to all waiting threads instead of single one thread.
What is daemon thread in Java?
A Daemon thread is
a background service thread which runs as a low priority thread and performs background operations like garbage collection
. JVM exits if only daemon threads are remaining. The setDaemon() method of the Thread class is used to mark/set a particular thread as either a daemon thread or a user thread.
Can we pause a thread?
Methods Used:
sleep(time): This is a method used to sleep the thread for some milliseconds time.
suspend(): This is a method used to suspend the thread
. The thread will remain suspended and won’t perform its tasks until it is resumed. resume(): This is a method used to resume the suspended thread.
How do you stop a thread execution in Java?
Whenever we want to stop a thread from running state by
calling stop() method of Thread class
in Java. This method stops the execution of a running thread and removes it from the waiting threads pool and garbage collected. A thread will also move to the dead state automatically when it reaches the end of its method.
How do we start and stop a thread in Java?
Can we call run method instead of start?
No, you can not directly call run method to start a thread
. You need to call start method to create a new thread. If you call run method directly , it won’t create a new thread and it will be in same stack as main.
How do you pause Runnables?
The thread can go into runnable state by using the static method
Thread. sleep(duration)
. This will pause the current thread to stop executing for that duration. Else if you want your thread to execute after some thread has finished then you can use the join() method of the thread class.
How do I run one thread after another?
We can use
use join() method of thread class
. To ensure three threads execute you need to start the last one first e.g. T3 and then call join methods in reverse order e.g. T3 calls T2. join, and T2 calls T1.
What is difference between wait () and sleep () method?
Wait() method releases lock during Synchronization. Sleep() method does not release the lock on object during Synchronization
.
Can we execute a program without main () method?
Yes, we can execute a java program without a main method by using a static block
. Static block in Java is a group of statements that gets executed only once when the class is loaded into the memory by Java ClassLoader, It is also known as a static initialization block.
Can two threads have same priority?
It is possible to have same priority to threads
. So CPU can decide which thread to run by using some algorithms.
Can we use static and synchronized together?
static methods can be synchronized
. But you have one lock per class. when the java class is loaded coresponding java.
Can we override start method in Java?
Can we override a start() method in Java?
Yes, we can override the start() method of a Thread class in Java
. We must call the super. start() method to create a new thread and need to call run() method in that newly created thread.
What will happen if we call run () directly without start ()?
If you call it directly, then it will execute not in another thread, but in the current thread. If start isn’t called, then
the Thread created will never run
. The main thread will finish and the Thread will be garbage collected.
What happens if we don’t override Run method?
Answer: If we don’t override run() method,
compiler will not flash any error and it will execute run() method of Thread class that has empty implemented
, So, there will be no output for this thread.
What is the default thread priority?
The default priority of a Java thread is
NORM_PRIORITY
. (A Java thread that doesn’t explicitly call setPriority runs at NORM_PRIORITY .) A JVM is free to implement priorities in any way it chooses, including ignoring the value.
Does multithreading use polling method?
The benefit of Java s multithreading is that
the main loop/polling mechanism is eliminated
. One thread can pause without stopping other parts of your program. Threads can be in several states like running, ready, suspended, blocked, resumed.
What is the difference between the start () and run () method?
What is difference between starting thread with Run () and start () method Mcq?
Explanation: run() method is used to define the code that constitutes the new thread, it contains the code to be executed.
start() method is used to begin execution of the thread that is execution of run()
.
Why do we call start method in thread instead of run?
Calling start () will start a new Thread and calling run() method does not start a new Thread
. If you call start() method on Thread, Java Virtual Machine will call run() method and two threads will run concurrently now – Current Thread and Other Thread or Runnable implementation.
What is wait () in Java?
What is the maximum thread priority in Java?
In Java, a thread’s priority is an integer in the range
1 to 10
. The larger the integer, the higher the priority. The thread scheduler uses this integer from each thread to determine which one should be allowed to execute.
How many threads can be created in Java?
Each JVM server can have a maximum of 256 threads
to run Java applications. In a CICS region you can have a maximum of 2000 threads. If you have many JVM servers running in the CICS region (for example, more than seven), you cannot set the maximum value for every JVM server.
Which method is used to dead the thread?
A thread dies naturally when its
run()
method exits normally. For example, the while loop in this method is a finite loop–it will iterate 100 times and then exit. A thread with this run() method will die naturally after the loop and the run() method completes.
Which method ensure that one thread starts after the completion of another?
By
using join
you can ensure running of a thread one after another.
