Java线程间同步的问题
大家好：
我的程序中定义了ThreadClass1 ThreadClass2 两个类(从Thread继承)。
有一个全局的数组A[10]
ThreadClass1中会write A[]
ThreadClass2中会Read A[]
为了保证A[0]..A[9]是ThreadClass1在同一次写入的数据，
该如何写?能提供例程吗？
谢谢！
[解决办法]
参考 notify() 和wait() 方法的用法 好象有个经典的生产者消费者的例子应该是处理这类问题的.
给一段参考代码吧:
public class WaitComm { public static void main(String[] args) { WFlagSend s = new WFlagSend(); WFlagRec r = new WFlagRec(s); Thread st = new Thread(s); Thread rt = new Thread(r); rt.setDaemon(true); st.start(); rt.start(); try { st.join(); while ( s.isValid ){ Thread.sleep(100); } }catch(InterruptedException e){ e.printStackTrace(); } }}class WFlagSend implements Runnable { int theValue; boolean isValid; public void run() { for ( int i=0; i<5; i++){ synchronized(this){ while (isValid){ try{ this.wait(); }catch(Exception e){e.printStackTrace();} } } theValue = (int)(Math.random()*256); System.out.println("sending " + theValue ); synchronized(this){ isValid = true; this.notify(); } } }}class WFlagRec implements Runnable { private WFlagSend theSender; public WFlagRec(WFlagSend sender){ theSender = sender; } public void run() { while ( true ) { synchronized(theSender) { while ( !theSender.isValid ){ try{ theSender.wait(); }catch(Exception e){e.printStackTrace();} } } System.out.println("received " + theSender.theValue); synchronized(theSender) { theSender.isValid = false; theSender.notify(); } } }}
[解决办法]
class Test{ public static void main(String[] args) { final Arrays a = new Arrays(); Thread t1 = new Thread() { public void run() { int j=1; while(true) { a.write(j++); } } }; Thread t2 = new Thread() { public void run() { while(true) { a.read(); } } }; t1.start(); t2.start(); }}class Array{ int n = 0; int[] num = new int[n]; boolean b = false; synchronized void write(int j) { int n = 0; try { if (b) { wait(); } } catch(Exception e) { System.out.println(e); } num[n++] = j; System.out.println(Thread.currentThread().getName()+" "+num[n]); b = true; notify(); } synchronized void read() { try { if(!b) { wait(); } } catch(Exception e) { System.out.println(e); } System.out.println(Thread.currentThread().getName()+" "+num[n]); b = false; notify(); }}
[解决办法]
public class Synchronized {
static class Account{
private double money=1000.0d;
public void nonSynDeposit(double fFees){
System.out.println("Account nonSynDeposit begin! money= "+this.money+"fFees= "+fFees);
System.out.println("Account nonSynDeposit sleep begin!");
try{
Thread.sleep(300);
}catch(InterruptedException e){
e.printStackTrace();
}
System.out.println("Account nonSynDeposit end! money= "+this.money);
}
public void nonSynWithdraw(double fFees){
System.out.println("Account nonSynWithdraw begin! money= "+this.money+" fFees= "+fFees);
System.out.println("Account nonSynWithdraw sleep begin!");
try{
Thread.sleep(400);
}catch(InterruptedException e){
e.printStackTrace();
}
System.out.println("Account nonSynWithdraw sleep begin!");
this.money=this.money-fFees;
System.out.println("Account nonSynWithdraw end money= "+this.money+" fFees= "+fFees);
}
public synchronized void synDeposit(double fFees){
System.out.println("Account synDeposit begin! money= "+this.money+" fFees= "+fFees);
System.out.println("Account synDeposit sleep begin!");
try{
Thread.sleep(300);
}catch(InterruptedException e){
e.printStackTrace();
}
System.out.println("Account synDeposit begin!");
this.money=this.money+fFees;
System.out.println("Account synDepost end! money= "+this.money+" fFees= "+fFees);
}
public synchronized void synWithdraw(double fFees){
System.out.println("Account synWithdraw begin! money= "+this.money+" fFees= "+fFees);
System.out.println("Account synWithdraw sleep begin!");
try{
Thread.sleep(400);
}catch(InterruptedException e){
e.printStackTrace();
}
System.out.println("Account synWithdraw sleep end!");
this.money=this.money-fFees;
System.out.println("Account synWithdraw end! money= "+this.money+" fFees= "+fFees);
}
static class AccessThread extends Thread{
private Account account=null;
private String method="";
public AccessThread(Account account,String method){
this.method=method;
this.account=account;
}
public void run(){
if(method.equals("nonSynDeposit")){
account.nonSynDeposit(500.0);
}else if(method.equals("nonSynWithdraw")){
account.nonSynWithdraw(200.0);
}else if(method.equals("synDeposit")){
account.synDeposit(500.0);
}else if(method.equals("synWithdraw")){
account.synWithdraw(200.0);
}
}
}
public static void main(String []args){
Account account=new Account();
System.out.println("使用非同步方法时：");
Thread threadA=new AccessThread(account,"nonSynDeposit");
Thread threadB=new AccessThread(account,"nonSynWithdraw");
threadA.start();
threadB.start();
try{
threadA.join();
threadB.join();
}catch(InterruptedException e){
e.printStackTrace();
}
System.out.println("");
account=new Account();
System.out.println("使用同步方法时：");
threadA=new AccessThread(account,"SynDeposit");
threadB=new AccessThread(account,"SynWithdraw");
threadA.start();
threadB.start();
}
}
}