按序打印
class Foo {
private CountDownLatch latch = new CountDownLatch(1);
private CountDownLatch sendcondLatch = new CountDownLatch(1);
public Foo() {
}
public void first(Runnable printFirst) throws InterruptedException {
// printFirst.run() outputs "first". Do not change or remove this line.
printFirst.run();
latch.countDown();
}
public void second(Runnable printSecond) throws InterruptedException {
latch.await();
// printSecond.run() outputs "second". Do not change or remove this line.
printSecond.run();
sendcondLatch.countDown();
}
public void third(Runnable printThird) throws InterruptedException {
sendcondLatch.await();
// printThird.run() outputs "third". Do not change or remove this line.
printThird.run();
}
public static void main(String[] args) {
Foo foo = new Foo();
new Thread(() -> {
try {
foo.first(() -> System.out.println("first"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
foo.second(() -> System.out.println("second"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
foo.third(() -> System.out.println("third"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
交替打印FooBar
class FooBar {
private int n;
private Semaphore foo = new Semaphore(1);
private Semaphore bar = new Semaphore(0);
public FooBar(int n) {
this.n = n;
}
public void foo(Runnable printFoo) throws InterruptedException {
for (int i = 0; i < n; i++) {
// 因为有1个许可，所以可以获取到
foo.acquire();
// printFoo.run() outputs "foo". Do not change or remove this line.
printFoo.run();
bar.release();
}
}
public void bar(Runnable printBar) throws InterruptedException {
for (int i = 0; i < n; i++) {
bar.acquire();
// printBar.run() outputs "bar". Do not change or remove this line.
printBar.run();
foo.release();
}
}
public static void main(String[] args) {
FooBar fooBar = new FooBar(30);
new Thread(() -> {
try {
fooBar.foo(() -> System.out.print("foo"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
fooBar.bar(() -> System.out.print("bar"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
打印0与奇偶数
class ZeroEvenOdd {
private int n;
private Semaphore zero = new Semaphore(1);
private Semaphore odd = new Semaphore(1);
private Semaphore even = new Semaphore(0);
public ZeroEvenOdd(int n) {
this.n = n;
}
// printNumber.accept(x) outputs "x", where x is an integer.
public void zero(IntConsumer printNumber) throws InterruptedException {
for (int i = 0; i < n; i++) {
zero.acquire();
printNumber.accept(0);
}
}
public void odd(IntConsumer printNumber) throws InterruptedException {
int i = 1;
while (i <= n ) {
odd.acquire();
printNumber.accept(i);
i += 2;
zero.release();
even.release();
}
}
public void even(IntConsumer printNumber) throws InterruptedException {
int i = 2;
while (i <= n) {
even.acquire();
printNumber.accept(i);
i += 2;
zero.release();
odd.release();
}
}
public static void main(String[] args) {
ZeroEvenOdd zeroEvenOdd = new ZeroEvenOdd(5);
new Thread(() -> {
try {
zeroEvenOdd.zero(System.out::println);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
zeroEvenOdd.even(System.out::println);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
zeroEvenOdd.odd(System.out::println);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
H2O
class H2O {
private final Semaphore hydrogenArrive = new Semaphore(2);
private final Semaphore oxygenArrive = new Semaphore(1);
CyclicBarrier barrier = new CyclicBarrier(3);
public H2O() {
}
public void hydrogen(Runnable releaseHydrogen) throws InterruptedException {
try {
hydrogenArrive.acquire();
barrier.await();
// releaseHydrogen.run() outputs "H". Do not change or remove this line.
releaseHydrogen.run();
} catch (BrokenBarrierException e) {
e.printStackTrace();
} finally {
hydrogenArrive.release();
}
}
public void oxygen(Runnable releaseOxygen) throws InterruptedException {
try {
oxygenArrive.acquire();
barrier.await();
// releaseOxygen.run() outputs "O". Do not change or remove this line.
releaseOxygen.run();
} catch (BrokenBarrierException e) {
e.printStackTrace();
} finally {
oxygenArrive.release();
}
}
public static void main(String[] args) {
H2O h2O = new H2O();
int n = 10;
for (int i = 0; i < n*2; i++) {
new Thread(() -> {
try {
h2O.hydrogen(() -> System.out.print("H"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
for (int i = 0; i < n; i++) {
new Thread(() -> {
try {
h2O.oxygen(() -> System.out.print("O"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
}
交替打印字符串
class FizzBuzz {
private int n;
private Semaphore normal = new Semaphore(1);
private Semaphore fizzSm = new Semaphore(0);
private Semaphore buzzSm = new Semaphore(0);
private Semaphore fizzBuzzSm = new Semaphore(0);
public FizzBuzz(int n) {
this.n = n;
}
// printFizz.run() outputs "fizz".
public void fizz(Runnable printFizz) throws InterruptedException {
for (int i = 3; i <= n; i = i + 3) {
// if (i % 3 == 0 && i % 5 != 0) {
fizzSm.acquire();
printFizz.run();
normal.release();
// }
}
}
// printBuzz.run() outputs "buzz".
public void buzz(Runnable printBuzz) throws InterruptedException {
for (int i = 5; i <= n; i = i + 5) {
// if (i % 3 != 0 && i % 5 == 0) {
buzzSm.acquire();
printBuzz.run();
normal.release();
// }
}
}
// printFizzBuzz.run() outputs "fizzbuzz".
public void fizzbuzz(Runnable printFizzBuzz) throws InterruptedException {
for (int i = 15; i <= n; i = i + 15) {
// if (i % 3 == 0 && i % 5 == 0) {
fizzBuzzSm.acquire();
printFizzBuzz.run();
normal.release();
// }
}
}
// printNumber.accept(x) outputs "x", where x is an integer.
public void number(IntConsumer printNumber) throws InterruptedException {
for (int i = 1; i <= n; i++) {
normal.acquire();
if (i % 3 == 0 && i % 5 == 0) {
fizzBuzzSm.release();
} else if (i % 3 == 0) {
fizzSm.release();
} else if (i % 5 == 0) {
buzzSm.release();
} else {
printNumber.accept(i);
normal.release();
}
}
}
public static void main(String[] args) throws InterruptedException {
FizzBuzz fizzBuzz = new FizzBuzz(16);
new Thread(() -> {
try {
fizzBuzz.fizz(() -> System.out.println("fizz"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
fizzBuzz.buzz(() -> System.out.println("buzz"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
fizzBuzz.fizzbuzz(() -> System.out.println("fizzBuzz"));
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
new Thread(() -> {
try {
fizzBuzz.number(System.out::println);
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
}
哲学家吃饭问题
下面的方法，只能一个一个的吃，当然也有其他的能一次让两个人吃的解法，不做具体展开。
class DiningPhilosophers2 {
public DiningPhilosophers2() {
}
private Semaphore leftForkPicked = new Semaphore(1);
private Semaphore rightForkPicked = new Semaphore(1);
private Semaphore oneByOne = new Semaphore(1);
// call the run() method of any runnable to execute its code
public void wantsToEat(int philosopher,
Runnable pickLeftFork,
Runnable pickRightFork,
Runnable eat,
Runnable putLeftFork,
Runnable putRightFork) throws InterruptedException {
oneByOne.acquire();
pickLeftFork.run();
pickRightFork.run();
eat.run();
putLeftFork.run();
putRightFork.run();
leftForkPicked.release();
rightForkPicked.release();
oneByOne.release();
}
public static void main(String[] args) throws InterruptedException {
DiningPhilosophers philosophers = new DiningPhilosophers();
Runnable pickLeftFork = () -> System.out.println(Thread.currentThread().getName() + ",1,1]");
Runnable pickRightFork = () -> System.out.println(Thread.currentThread().getName() + ",2,1]");
Runnable eat = () -> System.out.println(Thread.currentThread().getName() + ",0,3]");
Runnable putLeftFork = () -> System.out.println(Thread.currentThread().getName() + ",1,2]");
Runnable putRightFork = () -> System.out.println(Thread.currentThread().getName() + ",2,2]");
int num = 5;
for (int i = 0; i < 5; i++) {
int finalI = i;
new Thread(() -> {
try {
for (int j = 0; j < num; j++) {
philosophers.wantsToEat(finalI, pickLeftFork, pickRightFork, eat, putLeftFork,
putRightFork);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}, "[" + finalI + "").start();
}
Thread.currentThread().join();
}
}