Homework $4$

$1.(10$ pts$)$ For the following program, explain the interesting elements related to threads. Focus on

explaining the output of the program.

$1$ public class TaskThreadDemo $\{$

$2$ public static void main $($String args $[])\{$

$3$ String $[]$ sa $=\{"$a$","$X$","+","."\}$;

$4$ for $($String s: sa$)\{$

$5$ Runnable ps $=$ new PrintChar $($s$,200)$;

$6$ Thread ts $=$ new Thread $($ps$,$ s$)$;

$7$ ts$.$start $()$;

$8\}//$ end for each character

$9\}//$ end main

$10\}//$ end class TaskThreadDemo

$11$

$12$ class PrintChar implements Runnable $\{$

$13$ String ch;

$14$ int times;

$15$

$16$ public PrintChar $($String c$,$ int n$)\{$

$17$ ch $=$ c;

$18$ times $=$ n;

$19\}//$ end constructor

$20$

$21$ public void run $()\{$

$22$ for $($int i $=0$; i $<$ times; i$++)\{$

$23$ System.out.print $($ch$)$;

$24\}//$ end for loop

$25\}//$ end method run

$26\}//$ end class PrintChar

$2.(10$ pts$)$ What is changed if the method called on line $7,$ start$(),$ is replaced with run$()?$ Explain $($of

course$).$ Focus on explaining the output of the program.

$3.(10$ pts$)$ What is changed if the method Thread.yield$()$ is added between lines $23$ and $24?$ Explain.

Focus on explaining the output of the program.

$4.(10$ pts$)$ Modify the above program so that the Thread.sleep method is called after each character has

been printed causing it to sleep for $500$ milliseconds. Describe how that modification has altered the

output and explain why the change had the effect that you described.

$5.(10$ pts$)$ Modify the above program so that the Thread.sleep method is called after each thread is

created in the main method causing it to sleep for $500$ milliseconds. Describe how that modification has

altered the output and explain why the change had the effect that you described