多线程处理线程在java中的工作方式
下面是一段代码,我在某些方面感到困惑
public class SimpleThreads {
// Display a message, preceded by
// the name of the current thread
static void threadMessage(String message) {
String threadName =
Thread.currentThread().getName();
System.out.format("%s: %s%n",
threadName,
message);
}
private static class MessageLoop
implements Runnable {
public void run() {
String importantInfo[] = {
"Mares eat oats",
"Does eat oats",
"Little lambs eat ivy",
"A kid will eat ivy too"
};
try {
for (int i = 0;
i < importantInfo.length;
i++) {
// Pause for 4 seconds
Thread.sleep(4000);
// Print a message
threadMessage(importantInfo[i]);
}
} catch (InterruptedException e) {
threadMessage("I wasn't done!");
}
}
}
public static void main(String args[])
throws InterruptedException {
// Delay, in milliseconds before
// we interrupt MessageLoop
// thread (default one hour).
long patience = 1000 * 60 * 60;
// If command line argument
// present, gives patience
// in seconds.
if (args.length > 0) {
try {
patience = Long.parseLong(args[0]) * 1000;
} catch (NumberFormatException e) {
System.err.println("Argument must be an integer.");
System.exit(1);
}
}
threadMessage("Starting MessageLoop thread");
long startTime = System.currentTimeMillis();
Thread t = new Thread(new MessageLoop());
t.start();
threadMessage("Waiting for MessageLoop thread to finish");
// loop until MessageLoop
// thread exits
while (t.isAlive()) {
threadMessage("Still waiting...");
// Wait maximum of 1 second
// for MessageLoop thread
// to finish.
t.join(1000);
if (((System.currentTimeMillis() - startTime) > patience)
&& t.isAlive()) {
threadMessage("Tired of waiting!");
t.interrupt();
// Shouldn't be long now
// -- wait indefinitely
t.join();
}
}
threadMessage("Finally!");
}
}
我需要解释的部分是 长期耐心=1000*60*60
耐心的目的是什么?在下面显示的代码中,我认为它得到了另一个值,这取决于条件。正当如果是,我们如何获得命令行参数(即args[0])
if (args.length > 0) {
try {
patience = Long.parseLong(args[0]) * 1000;
} catch (NumberFormatException e) {
System.err.println("Argument must be an integer.");
System.exit(1);
}
}
}
# 1 楼答案
您在此处使用的是耐心变量:
现在
System.currentTimeMillis()
returns以毫秒为单位显示当前时间。你把耐心定义为假设你通过的args[0]为1,你得到的最终耐心为3600000,相当于一小时,即60分钟*60秒*1000毫秒
所以,若您在一小时内到达if块并且线程处于活动状态,那个么您将使用连接线程api无限期地等待线程完成上述条件