I am a newbie, and I have a question about multithreading: <br>if I need several threads, i.e.: 7 threads, they all share<br>an int value. Three of them will check if this value is less<br>than 0, if so, increase it by adding a ramdom value; other threee will check if it is bigger than 0, if so, they will decrease it by using a random value; that another thread makes sure that value will not be zero. Can anyone give me an idea? Do I need to create 3 different thread classes<br>or just declare 7 threads under Thread? Thx in advance.
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Newbie question:multithreading and shared value
- Thread starter victor1
- Start date
Hi!<br><br>Here is a little example, safe stack implementation. I think it will help you...<br><br>Bye, Otto.<br>*************************************<br>class WN2 {<br> static MyStack ms=new MyStack();<br> final static int STACK_SIZE=10;<br><br> public static void main(String[] args) {<br> WN2 wn=new WN2();<br> }<br><br> WN2() {<br> Thread th;<br><br> th=new Thread(new Fogyaszto());<br> th.setPriority(Thread.NORM_PRIORITY);<br> th.start(); // start a thread to pop values<br> th=new Thread(new Termelo());<br> th.setPriority(Thread.MIN_PRIORITY);<br> th.start(); // start a thread to push values<br> }<br><br> class Termelo implements Runnable {<br> public void run() {<br> while (true) {<br> ms.push('P');<br> }<br> }<br> }<br><br> class Fogyaszto implements Runnable {<br> public void run() {<br> while (true) {<br> ms.pop();<br> }<br> }<br> }<br>}<br>class MyStack {<br> int idx=0;<br> char[] data=new char[WN2.STACK_SIZE];<br> <br> synchronized void push(char c) {<br> while (idx==WN2.STACK_SIZE) {<br> System.out.println("Wait to push..."
;<br> try {<br> wait();<br> } catch (InterruptedException e) { System.out.println("Wait error." }<br> }<br> data[idx++]=c;<br> notify();<br> }<br> synchronized char pop() {<br> while (idx==0) {<br> System.out.println("Wait to pop..."<br> try {<br> wait();<br> } catch (InterruptedException e) { System.out.println("Wait error." }<br> }<br> char c=data[--idx];<br> notify();<br> return c;<br> }<br>}<br>
;<br> try {<br> wait();<br> } catch (InterruptedException e) { System.out.println("Wait error." }<br> }<br> data[idx++]=c;<br> notify();<br> }<br> synchronized char pop() {<br> while (idx==0) {<br> System.out.println("Wait to pop..."<br> try {<br> wait();<br> } catch (InterruptedException e) { System.out.println("Wait error." }<br> }<br> char c=data[--idx];<br> notify();<br> return c;<br> }<br>}<br> - Status