[英]Printing Keys of HashMap with two threads in java?
enter code hereSuppose I have two threads Thread1 and Thread2 and below hashmap with null values. 假设我有两个线程Thread1和Thread2及以下具有空值的hashmap。 Now I want to print the Key of HashMap with respective thread which is executing print statement , without printing it again
现在我想使用正在执行print语句的相应线程来打印HashMap的Key,而无需再次打印它
Input Hashmap:
输入哈希图:
"Hello" null “你好” null
"Customer" null “客户”为空
"Value" null “值”为null
"Bye" null “再见” null
Output:
输出:
"Bye" : Printed by Thread1" “再见”:由线程1打印“
"Hello" :"Printed by Thread2" “ Hello”:“由Thread2打印”
"Value" :"Printed by Thread2" “ Value”:“由Thread2打印”
"Customer" : "Printed by Thread1" “客户”:“由Thread1打印”
So Far I am not able to print with below code. 到目前为止,我无法使用以下代码进行打印。
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Test2 implements Runnable {
volatile static HashMap<String, String> map;
static Object mutex = new Object();
static volatile int i = 1;
public static void main(String[] args) throws InterruptedException {
map = new HashMap();
map.put("Public", null);
map.put("Sort", null);
map.put("Message", null);
map.put("Customer", null);
map.put("Bank", null);
// ConcurrentHashMap chm= new ConcurrentHashMap(map);
Collections.synchronizedMap(map);
Thread t1 = new Thread(new Test2());
Thread t2 = new Thread(new Test2());
t1.start();
t2.start();
}
@Override
public void run() {
synchronized (mutex) {
for (Map.Entry entry : map.entrySet()) {
if (entry.getValue() == null) {
System.out.println(entry.getKey() + "\" : \"Printed by " + Thread.currentThread().getName() + '\"');
map.put((String) entry.getKey(), Thread.currentThread().getName());
if (Thread.currentThread().getName().contains("0")&&i==1) {
try {
mutex.notifyAll();
mutex.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (Thread.currentThread().getName().contains("1")&&i<=1) {
try {
mutex.notifyAll();
i++;
mutex.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
mutex.notifyAll();
}
}
}
Just pass each key as a task to an ExecutorService with 2 threads : 只需将每个键作为任务传递给具有2个线程的ExecutorService:
ExecutorService executorService = Executors.newFixedThreadPool(2);
map.keySet().forEach(key -> executorService
.execute(() -> System.out.println('\"' + key + "\" : \"Printed by " + Thread.currentThread().getName() + '\"')));
executorService.shutdown();
executorService.awaitTermination(5, TimeUnit.SECONDS);
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