Please help

Question about the task

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For some reason instead of only displaying the state once, it continually displays it whilst it's running. It also does not display "TERMINATED". Is this because I setDeamon to true, and so it shuts down as soon as the other Thread stops?

Create a LoggingStateThread thread class, which will display all of the states (State) of the thread passed to the constructor.
The LoggingStateThread thread must terminate itself after the thread passed to the constructor has stopped.
The main() method is not tested.

Requirements:

Create a LoggingStateThread class in a separate file. It must inherit the Thread class.
The LoggingStateThread class must have a field for the thread it will monitor. This field must be initialized through the constructor.
Override the LoggingStateThread class's run() method.
After it starts running, the LoggingStateThread class should display changes to the passed thread's state.
After the monitored thread stops, the LoggingStateThread thread must also stop running.

package com.codegym.task.task25.task2506; /* Monitoring thread state */ public class Solution { public static void main(String[] args) throws InterruptedException { Thread target = new Thread(); LoggingStateThread loggingStateThread = new LoggingStateThread(target); loggingStateThread.start(); // NEW Thread.sleep(100); target.start(); // RUNNABLE Thread.sleep(100); // TERMINATED } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

2 March 2021, 17:25

solution

#1 State is an enum inside the Thread class. You can access it with getState(). Comparing states would be cleaner than comparing Strings. So, instead of String state, you can use State state and compare with normal comparisons (== or !=) #2 with that being said, I think you could just move line 23 to outside the while loop and pass this task. This line is the line that is continuing to print the state every single loop cycle, which will fill your screen with outputs. Because a while loop will break when State = TERMINATED, that would never be printed without that last line outside the loop.

Anthony Chalk

Level 30 , London, United Kingdom

2 March 2021, 20:03

That was a silly mistake; thank you. Even after I moved it out of the loop, it printed TERMINATED twice, until I added

this.interrupt();

after the print command. Why? Also, since this thread should shut down after the other thread has stopped, why does it print TERMINATED at all? Edit: Part one, when I reran the code it still randomly prints TERMINATED twice, and it does the same when I remove interrupt(), so now I'm even more confused

Guadalupe Gagnon

Level 37 , Tampa, United States

2 March 2021, 20:19

useful

It is a common misconception that interrupt does something fancy. All it does is change an internal boolean (i think its called interrupted) from false to true, and when that boolean is true a lot of the methods, such as wait() and sleep(), will throw an InterruptedException. One that does not throw an exception is the run() method. It is printing it twice because sometimes between when the code checks if the state == terminated on line 17 and when it gets the current state on line 18, the state switches. You would have to get the state first and then check it to prevent this:

String state;
while (!(state = thread.getState().toString()).equalsIgnoreCase("terminated")){

Anthony Chalk

Level 30 , London, United Kingdom

2 March 2021, 20:29

Thanks. Going to take some getting used to this stuff