我运行主方法一段时间后,它总是不打印任何内容。
但如果我取消注释"System.out.println(111(;"one_answers"System.out_println(222(;",我想它会正常运行。
我获取"soldWorker"线程和"refundWorker"的转储,它们在if
判断处停止。
public class ProducerAndConsumer2 {
public static void main(String[] args) {
SyncTikcet2 syncTikcet = new SyncTikcet2(1);
Runnable syncSoldTicket = () -> syncTikcet.soldTicket();
Runnable syncRefundTicket = () -> syncTikcet.refund();
new Thread(syncSoldTicket, "soldWorker").start();
new Thread(syncRefundTicket, "refundWorker").start();
}
}
class SyncTikcet2 {
private Integer ticketNum;
public SyncTikcet2(Integer ticketNum) {
this.ticketNum = ticketNum;
}
public void soldTicket() {
while (true) {
if (ticketNum > 0) {
ticketNum = ticketNum - 1;
System.out.println("sold ticket,the num is" + ticketNum);
} else {
// System.out.println(111);
}
}
}
public void refund() {
while (true) {
if (ticketNum == 0) {
ticketNum = ticketNum + 1;
System.out.println("refund ticket,the num is" + ticketNum);
} else {
// System.out.println(222);
}
}
}
public Integer getTicketNum() {
return ticketNum;
}
public void setTicketNum(Integer ticketNum) {
this.ticketNum = ticketNum;
}
}
如果您没有使字段变得易失性,那么线程就没有理由重新读取它没有更改的值。
尝试使用private volatile int ticketNum
我建议使用基元,例如int
,除非必须使用Object引用。它不仅更快,而且还表明您不希望值为null
。