文章目录
V2.0 使用wait()和notifyAll()
2.1 优缺点
进程可以终止。
便于理解和实现。
2.2 代码
package org.example;
public class SkMain {
public static void main(String[] args) {
ABCPrinter printer = new ABCPrinter();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 5; i++) {
printer.printA();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 5; i++) {
printer.printB();
}
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 5; i++) {
printer.printC();
}
}
}).start();
}
}
class ABCPrinter {
private volatile int value = 1;
public void printA() {
synchronized (this) {
while(value != 1) {
try {
wait();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
System.out.println("A");
value++;
notifyAll();
}
}
public void printB() {
synchronized (this) {
while(value != 2) {
try {
wait();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
System.out.println("B");
value++;
notifyAll();
}
}
public void printC() {
synchronized (this) {
while(value != 3) {
try {
wait();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
System.out.println("C");
value = 1;
notifyAll();
}
}
}
Reference
https://blog.csdn.net/realYuzhou/article/details/108367264
V1.0 面试挂的比较low的版本，只使用synchronized
1.1 缺点
程序不会终止
1.2 代码
A.java
package org.example;
public class A implements Runnable {
private B b;
private C c;
private int N = 5;
private boolean isFinish = false;
@Override
public void run() {
while (N > 0) {
synchronized (c) {
if (N ==5 && !isFinish) {
core();
} else if (c.isFinish() && !isFinish) {
// wait c finish.
core();
}
}
}
}
private void core() {
isFinish = false;
System.out.println("A");
N--;
isFinish = true;
b.setFinish(false);
}
public void setFinish(boolean finish) {
isFinish = finish;
}
public boolean isFinish() {
return isFinish;
}
public void setC(C c) {
this.c = c;
}
public void setB(B b) {
this.b = b;
}
}
B.java
package org.example;
public class B implements Runnable {
A a;
C c;
private boolean isFinish = false;
@Override
public void run() {
while(true) {
synchronized (a) {
if (a.isFinish() && !isFinish) {
isFinish = false;
System.out.println("B");
isFinish = true;
c.setFinish(false);
}
}
}
}
public boolean isFinish() {
return isFinish;
}
public void setFinish(boolean finish) {
isFinish = finish;
}
public void setA(A a) {
this.a = a;
}
public void setC(C c) {
this.c = c;
}
}
C.java
package org.example;
public class C implements Runnable {
B b;
A a;
private boolean isFinish = false;
@Override
public void run() {
while (true) {
synchronized (b) {
if (b.isFinish() && !isFinish) {
isFinish = false;
System.out.println("C");
isFinish = true;
a.setFinish(false);
}
}
}
}
public boolean isFinish() {
return isFinish;
}
public void setFinish(boolean finish) {
isFinish = finish;
}
public void setB(B b) {
this.b = b;
}
public void setA(A a) {
this.a = a;
}
}
Main.java
package org.example;
public class Main {
public static void main(String[] args) {
A a = new A();
B b = new B();
C c = new C();
b.setA(a);
a.setB(b);
c.setB(b);
c.setA(a);
b.setC(c);
a.setC(c);
Thread threadA = new Thread(a);
Thread threadB = new Thread(b);
Thread threadC = new Thread(c);
threadA.start();
threadB.start();
threadC.start();
}
}