java多线程编程题之连续打印abc的几种解法

Question

如题所述

Answer 1

package com.demo.test;/**
* 基于两个lock实现连续打印abcabc....
* @author lixiaoxi
* */public class TwoLockPrinter implements Runnable { // 打印次数
private static final int PRINT_COUNT = 10; // 前一个线程的打印锁
private final Object fontLock; // 本线程的打印锁
private final Object thisLock; // 打印字符
private final char printChar; public TwoLockPrinter(Object fontLock, Object thisLock, char printChar) { this.fontLock = fontLock; this.thisLock = thisLock; this.printChar = printChar;
}

@Override public void run() { // 连续打印PRINT_COUNT次
for (int i = 0; i < PRINT_COUNT; i++) { // 获取前一个线程的打印锁
synchronized (fontLock) { // 获取本线程的打印锁
synchronized (thisLock) { //打印字符 System.out.print(printChar); // 通过本线程的打印锁唤醒后面的线程
// notify和notifyall均可,因为同一时刻只有一个线程在等待 thisLock.notify();
} // 不是最后一次则通过fontLock等待被唤醒 // 必须要加判断，不然虽然能够打印10次，但10次后就会直接死锁
if(i < PRINT_COUNT - 1){ try { // 通过fontLock等待被唤醒 fontLock.wait();

} catch (InterruptedException e) {
e.printStackTrace();
}
}

}
}
} public static void main(String[] args) throws InterruptedException { // 打印A线程的锁
Object lockA = new Object(); // 打印B线程的锁
Object lockB = new Object(); // 打印C线程的锁
Object lockC = new Object();
// 打印a的线程
Thread threadA = new Thread(new TwoLockPrinter(lockC, lockA, 'A')); // 打印b的线程
Thread threadB = new Thread(new TwoLockPrinter(lockA, lockB, 'B')); // 打印c的线程
Thread threadC = new Thread(new TwoLockPrinter(lockB, lockC, 'C')); // 依次开启a b c线程 threadA.start();
Thread.sleep(100); // 确保按顺序A、B、C执行 threadB.start();
Thread.sleep(100);
threadC.start();
Thread.sleep(100);
}

}