Please help me make sense of main solution.

Question about the task

Under discussion

I don't understand the logic of lines 14-16 from the Solution class. Why call Thread and not call logginstateThread.sleep? Why when target.start is called the state of loggingStateThread changes ? Is it because loggingStateThread does not create a new thread in its constructor and it uses the target thread? How is the terminated status achieved? Because there are no more methods called on the target thread? Please ignore the code in the LoggingStateThread, I actually used the code from the mentor because I didn't know how to solve this.

public class LoggingStateThread extends Thread {
    Thread thread;

    LoggingStateThread (Thread thread){
        this.thread = thread;
        thread.setDaemon(true);
    }

    @Override
    public void run() {
        State currentState = thread.getState();
        System.out.println(currentState);

        State newState;
        do {
            if ((newState = thread.getState()) != currentState) {
                currentState = newState;
                System.out.println(newState);
            }
        } while (!currentState.equals(State.TERMINATED));
    }
}

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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Ian De Bie Full Stack Developer

12 September 2022, 02:16

**my answers to your questions** Q: Why call Thread and not call logginstateThread.sleep? A: this causes the currently executing thread to sleep, which gives your logging thread time to log the state before the main target thread changes state again. Q: Why when target.start is called the state of loggingStateThread changes? Is it because loggingStateThread does not create a new thread in its constructor and it uses the target thread? A: the state that you are monitoring is the target thread. before target start it is in new status, after target start it is runnable. Q: How is the terminated status achieved? Because there are no more methods called on the target thread? A: it terminated because there was no more lines of code to run.