Thread.yield()
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| class FooBar {
private int n;
private volatile boolean shouldPrintFoo = true;
public FooBar(int n) {
this.n = n;
}
public void foo(Runnable printFoo) throws InterruptedException {
for (int i = 0; i < n; i++) {
while (!shouldPrintFoo) {
Thread.yield();
}
printFoo.run();
shouldPrintFoo = false;
}
}
public void bar(Runnable printBar) throws InterruptedException {
for (int i = 0; i < n; i++) {
while (shouldPrintFoo) {
Thread.yield();
}
printBar.run();
shouldPrintFoo = true;
}
}
}
|
synchronized
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| class FooBar {
private int n;
private final Object lock = new Object();
private boolean shouldPrintFoo = true;
public FooBar(int n) {
this.n = n;
}
public void foo(Runnable printFoo) throws InterruptedException {
for (int i = 0; i < n; i++) {
synchronized (lock) {
while (!shouldPrintFoo) {
lock.wait();
}
printFoo.run();
shouldPrintFoo = false;
lock.notifyAll();
}
}
}
public void bar(Runnable printBar) throws InterruptedException {
for (int i = 0; i < n; i++) {
synchronized (lock) {
while (shouldPrintFoo) {
lock.wait();
}
printBar.run();
shouldPrintFoo = true;
lock.notifyAll();
}
}
}
}
|
注意使用 while 与 notifyAll。
References
1115. Print FooBar Alternately