Page 163 - CTS - CSA TP - Volume 2

COMPUTER SOFTWARE APPLICATION - CITS

2 join() Method:
• Purpose: Waits for the thread on which it’s called to die.
• Syntax:join()
• Use Case:
• Ensures that the current thread waits for the completion of the thread on which join() is called before proceeding.
class JoinExample extends Thread {
public void run() {
System.out.println(“Thread is running...”);
}
public static void main(String args[]) throws InterruptedException {
JoinExample joinThread = new JoinExample();
joinThread.start();
joinThread.join();
System.out.println(“Thread has finished”);
}
}
Explanation:
1 JoinExample Class:

• This class extends the Thread class, indicating that instances of this class can be executed as separate
threads.
2 run() Method:
• The run() method overrides the run() method of the Thread class, defining the behavior of the thread when
it starts.
• Inside the run() method, it prints “Thread is running...” to indicate that the thread has started its execution.
3 main() Method:
• This method serves as the entry point of the program.
• Inside main():
• An instance of the JoinExample class named joinThread is created.
• The start() method is invoked on joinThread to begin the execution of the thread.
• The join() method is called on joinThread. This causes the main thread to wait until joinThread finishes its
execution before continuing further.
• After joinThread finishes executing, “Thread has finished” is printed to indicate that the join operation has
completed.
4 Output:
• When the program is executed:
• The thread starts its execution and prints “Thread is running...”.
• Meanwhile, the main thread waits for joinThread to finish its execution using the join() method.
• Once joinThread finishes executing, “Thread has finished” is printed by the main thread.
5 Exception Handling:
• The join() method can throw an InterruptedException if the thread is interrupted while waiting for another
thread to finish.
• In this example, the main() method declares that it throws InterruptedException. However, no explicit handling
of the exception is performed within the method.

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CITS : IT & ITES - Computer Software Application - Exercise 104