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package example.ThreadExample;
/**
* 同步
* - Process synchronization
* - Thread synchronization
* - 相互排斥 mutual exclusive
* - 同步方法 sync method
* - 同步區塊 sync block
* - 靜態同步 static sync
* - 執行緒間的通信 inter-thread communication
*/
public class SynchExample {
public static void main(String[] args) {
// example without sync.
// exampleWithoutSync();
// example with sync.
exampleWithSync();
}
public static void exampleWithoutSync() {
DemoProblemWithoutSync demo = new DemoProblemWithoutSync();
JobThreadFirst jt1 = new JobThreadFirst(demo);
JobThreadSecond jt2 = new JobThreadSecond(demo);
jt1.start();
jt2.start();
}
/**
* 所謂同步，就是可以讓某執行緒在使用記憶體資源時，同時鎖住資源讓其他執行緒無法改動。
*/
public static void exampleWithSync() {
DemoProblemWithoutSync demo = new DemoProblemWithoutSync();
FirstThreadWithSync ftws = new FirstThreadWithSync(demo);
SecondThreadWithSync stws = new SecondThreadWithSync(demo);
ftws.start();
stws.start();
}
}
class DemoProblemWithoutSync {
/**
* 未使用sync方式
* @param n
*/
public void printDemo(int n) {
for (int i=1; i<=5; i++) {
System.out.println("output: " + i*n);
try {
Thread.sleep(500);
} catch (Exception e) {
System.out.println(e);
}
}
}
/**
* 使用sync方式
* @param n
*/
public synchronized void printDemoWithSync(int n) {
for (int i=1; i<=5; i++) {
System.out.println("output: " + i*n);
try {
Thread.sleep(500);
} catch (Exception e) {
System.out.println(e);
}
}
}
}
class JobThreadFirst extends Thread {
DemoProblemWithoutSync demo;
JobThreadFirst(DemoProblemWithoutSync demo) {
this.demo = demo;
}
public void run() {
demo.printDemo(10);
}
}
class JobThreadSecond extends Thread {
DemoProblemWithoutSync demo;
JobThreadSecond(DemoProblemWithoutSync demo) {
this.demo = demo;
}
public void run() {
demo.printDemo(100);
}
}
class FirstThreadWithSync extends JobThreadFirst {
FirstThreadWithSync(DemoProblemWithoutSync demo) {
super(demo);
}
public void run() {
demo.printDemoWithSync(10);
}
}
class SecondThreadWithSync extends JobThreadSecond {
SecondThreadWithSync(DemoProblemWithoutSync demo) {
super(demo);
}
public void run() {
demo.printDemoWithSync(100);
}
}