Controlling individual threads

[youngstorm]

Hi, I am new to threads and have made a test program. The code is short. I am trying to control each thread. I am not sure if my method is right. Can someone please help? I can not find the answer in books or on the internet, though, it could be my own mindset. I am getting the following error:

############# Start javac output #########################
exec: javac -g threadTest.java

threadTest.java:13: cannot find symbol
symbol : method getcalcDone()
location: class java.lang.Thread
while (t1.getcalcDone() == false); //This loop will run till thread 1 has made it's calculation.
^
threadTest.java:21: cannot find symbol
symbol : variable t1
location: class threadTest
t1.calc(5, 3); // This SHOULD add 5 and 3 together. Not sure if I can control individual threads like this.
^
threadTest.java:22: cannot find symbol
symbol : variable t1
location: class threadTest
t2.calc(t1.results, 10); // Add the results of the first calculation and 10 together.
^
threadTest.java:22: cannot find symbol
symbol : variable t2
location: class threadTest
t2.calc(t1.results, 10); // Add the results of the first calculation and 10 together.
^
4 errors
############# End javac output #########################


############# Start Java Code #########################

import java.util.*;
 
public class threadTest extends Thread
{
 
	public static void main(String[] args) 
	{
		Thread t1 = new threadTest();
		Thread t2 = new threadTest();
 
		t1.start();
 
		while (t1.getcalcDone() == false); //This loop will run till thread 1 has made it's calculation.
 
		t2.start();		
 
	}
 
	public void run()
   {
	   t1.calc(5, 3); // This SHOULD add 5 and 3 together. Not sure if I can control individual threads like this.
		t2.calc(t1.results, 10); // Add the results of the first calculation and 10 together.
	}
 
}
 
 
class Thread1 extends Thread
{
   int a = 0;
	int b = 0;
	int results = 0;
	boolean calcDone = false;
 
   public Thread1(int a, int b)
	{
	    this.a = a;
		 this.b = b;
	}
 
   void calc(int a, int b)
	{
	    results = a + b;
		 calcDone = true;
	}
 
   boolean getcalcDone()
	{
	    return calcDone;
	}
}

################## End Java Code #######################

Thank you for any ideas.
Youngstorm

[copeg]

This isn't a thread problem per se but rather an accumulation of several syntax errors. First, you are abstracting the threadTest class to a Thread, which does not contain the methods you are calling. Second, threadTest class does not contain these methods, but Thread1 does. Thirdly, your t1/t2 variables in the threadTest.run method are out of scope.

[youngstorm]

Thank you for taking the time to respond.

First, you are abstracting the threadTest class to a Thread, which does not contain the methods you are calling. Second, threadTest class does not contain these methods, but Thread1 does.

How do I go about properly using these methods?

Thirdly, your t1/t2 variables in the threadTest.run method are out of scope.

I;m not sure I really understand this part, as it relates to threads. If I move the thread creation statements out of main, I get more errors than before. The new ones are as follows.

######################

threadTest.java:11: non-static variable t1 cannot be referenced from a static context
t1.start();
^
threadTest.java:13: non-static variable t1 cannot be referenced from a static context
while (t1.getcalcDone() == false); //This loop will run till thread 1 has made it's calculation.

######################

Again, I may be thinking about threads all wrong. Sorry if I'm causing utter confusion.

[copeg]

Again, this isn't a thread issue, its a syntax and programming flow problem.

threadTest t1 = new threadTest();

This allows the reference t1 access to the methods in threadTest. This will not fix your problem however, since you cannot call the methods defined in the class Thread1 from a reference (t1).

I suggest you read some beginning tutorials on the subjects of variable scope and how to define an object and write a class before diving into multi-threading.

[youngstorm]

Thanks. I'll do that and have some already.