Test the inter-Thread Synchronization in j2m2.

Y and wait are used for thread synchronization. Below are three simple examples;

Example 1:

Public class synobject {</P> <p> private thread m_synt; <br/> Object OBJ = new object (); </P> <p> Public void start () {<br/> m_synt = new synt (1); <br/> m_synt.start (); <br/> New synt (2 ). start (); <br/>}</P> <p> Public void process () {<br/> synchronized (OBJ) {<br/> obj. Y (); <br/>}</P> <p> private class synt extends thread {<br/> int id = 0; <br/> Public synt (INT value) {<br/> id = value; <br/>}< br/> Public void run () {<br/> int icount = 0; <br/> while (true) {<br/> system. out. println ("ID:" + ID + "Run:" + icount ++); <br/> try {<br/> sleep (100 ); <br/>} catch (interruptedexception IE) {</P> <p >}< br/> synchronized (OBJ) {<br/> try {<br/> obj. wait (); <br/>}catch (interruptedexception IE) {<br/> system. out. println ("ie:" + IE. getmessage (); <br/>}< br/>} 

In the MIDlet, press the key to trigger the process. Each time the process is pressed, it runs cyclically once. The process is controlled by the object obj!

 

Example 2:

Simple producer-consumer problem: one producer and one consumer

Public class queue {<br/> int value; <br/> Boolean bfull = false; </P> <p> Public synchronized void put (int I) {<br/> // synchronized (this) {<br/> If (! Bfull) {<br/> value = I; <br/> bfull = true; <br/> running y (); <br/>}< br/> try {<br/> wait (); <br/>}catch (exception e) {<br/> E. printstacktrace (); <br/>}< br/> //} <br/>}< br/> Public synchronized int get () {<br/> // synchronized (this) {<br/> If (! Bfull) {</P> <p> try {<br/> wait (); <br/>}catch (exception e) {<br/> E. printstacktrace (); <br/>}</P> <p> bfull = false; <br/> Y (); <br/>/}< br/> return value; <br/>}< br/>} 

Producer:

Class producer extends thread {<br/> queue Q; <br/> static int s_id = 0; <br/> int m_id = 0; <br/> producer (queue q) {<br/> This. Q = Q; <br/> m_id = s_id ++; <br/>}< br/> Public void run () {<br/> // synchronized (q) {<br/> for (INT I = 0; I <100; I ++) {<br/> q. put (I); <br/> system. out. println ("ID:" + m_id + "producer put" + I); <br/>}< br/>/}< br/>}< br/>} 

Consumer:

Class consumer extends thread {<br/> queue Q; <br/> static int s_id = 0; <br/> int m_id = 0; <br/> consumer (queue q) {<br/> This. Q = Q; <br/> m_id = s_id ++; <br/>}< br/> Public void run () {<br/> int value = 0; <br/> while (true) {<br/> // synchronized (q) {<br/> value = Q. get (); <br/> If (m_id = 1) {<br/> system. out. println (value); <br/>}< br/> // system. out. println ("ID:" + m_id + "consumer get" + q. get (); <br/>/}< br/>}< br/>} 

 

Example 3: Multiple producers and consumers

Public class queue2 extends queue {</P> <p> Private Static final int buff_len = 2; </P> <p> int [] m_iqueue = new int [buff_len]; <br/> int m_ireadindex = 0; <br/> int m_iwriteindex = 0; </P> <p> Private Static final int state_empty = 0; <br/> Private Static final int state_normal = 1; <br/> Private Static final int state_full = 2; </P> <p> int m_istate = state_normal; </P> <p> Object m_objr = new object (); <br/> Object m_objw = new object (); </P> <p> Public void put (INT value) {<br/> synchronized (m_objw) {<br/> If (m_iwriteindex + 1) % buff_len) = m_ireadindex) {<br/> // full <br/> system. out. println ("full"); <br/> m_istate = state_full; <br/> try {<br/> m_obj?wait (); <br/>} catch (interruptedexception IE) {</P> <p >}< br/>}</P> <p> synchronized (m_objr) {<br/> m_iwriteindex = (m_iwriteindex + 1) % buff_len; <br/> m_iqueue [m_iwriteindex] = value; </P> <p> If (m_istate = state_empty) {<br/> // system. out. println ("put policy"); <br/> m_istate = state_normal; <br/> m_objr.y y (); <br/>}</P> <p> Public int get () {<br/> synchronized (m_objr) {<br/> If (m_ireadindex = m_iwriteindex) {<br/> // empty <br/> m_istate = state_empty; <br/> system. out. println ("empty"); <br/> try {<br/> m_objr.wait (); <br/>} catch (interruptedexception IE) {</P> <p >}< br/>}</P> <p> int value = 0; </P> <p> synchronized (m_objw) {<br/> m_ireadindex = (m_ireadindex + 1) % buff_len; <br/> value = m_iqueue [m_ireadindex]; </P> <p> If (m_istate = state_full) {<br/> // system. out. println ("Get policy"); <br/> m_istate = state_normal; <br/> m_obj1_1_y (); <br/>}< br/> return value; <br/>}< br/>} 

In this case, two objects need to be used to control synchronization. One is used to control the producer and the other is used to control the consumer;