Java的多線程機制
實例一：
//題目：有三個線程分別打印A、B、C,請用多線程編程實現，在屏幕上循環打印10次ABCABC…
public class SleepExample extends Thread {
private static int currentCount = 0;
public SleepExample(String name) {
this.setName(name);
}
@Override
public void run() {
while (currentCount < 30) {
switch (currentCount % 3) {
case 0:
if ("A".equals(getName())) {
System.out.print("A");
currentCount++;
}
break;
case 1:
if ("B".equals(getName())) {
System.out.print("B");
currentCount++;
}
break;
case 2:
if ("C".equals(getName())) {
System.out.print("C");
currentCount++;
}
break;
}
}
}
public static void main(String[] args) {
new SleepExample("A").start();
new SleepExample("B").start();
new SleepExample("C").start();
}
}實例二：
//編寫一個程序使兩個線程陷入死鎖
public class DeadlockExample {
String resource1 = "資源1";
String resource2 = "資源2";
Thread t1 = new Thread("線程1") {
public void run() {
while (true) {
synchronized (resource1) {
synchronized (resource2) {
System.out.println("線程1擁有"+resource1+" 需要"+resource2);
}
}
}
}
};
Thread t2 = new Thread("線程2") {
public void run() {
while (true) {
synchronized (resource2) {
synchronized (resource1) {
System.out.println("線程2擁有"+resource2+" 需要"+resource1);
}
}
}
}
};
public static void main(String a[]) {
DeadlockExample test = new DeadlockExample();
test.t1.start();
test.t2.start();
}
}實例三：
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
//一個線程打印 1~52，另一個線程打印字母A-Z。打印順序爲12A34B56C……5152Z
public class ThreadCommunicationTest {
private final Lock lock = new ReentrantLock();
private final Condition conditionA = lock.newCondition();
private final Condition conditionB = lock.newCondition();
private static char currentThread = 'A';
public static void main(String[] args) {
ThreadCommunicationTest test = new ThreadCommunicationTest();
ExecutorService service = Executors.newCachedThreadPool();
service.execute(test.new RunnableA());
service.execute(test.new RunnableB());
service.shutdown();
}
private class RunnableA implements Runnable {
public void run() {
for (int i = 1; i <= 52; i++) {
lock.lock();
try {
while (currentThread != 'A') {
try {
conditionA.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println(i);
if (i % 2 == 0) {
currentThread = 'B';
conditionB.signal();
}
} finally {
lock.unlock();
}
}
}
}
private class RunnableB implements Runnable {
@Override
public void run() {
for (char c = 'A'; c <= 'Z'; c++) {
lock.lock();
try {
while (currentThread != 'B') {
try {
conditionB.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println(c);
currentThread = 'A';
conditionA.signal();
} finally {
lock.unlock();
}
}
}
}
}多線程詳解請參考http://blog.sina.com.cn/s/blog_6d5c82a70100m30t.html
