昨天上午笔试的，隔了一天才来写，好多忘了。。

选择题：

有给二叉树先序遍历、后续遍历，让求中序遍历的题。

问Math.round(-8.5)返回什么类型？

这题果然答错了，回来试了一下答案是long -8。

问答题：

给了一个用户注册消费的程序让分析有什么问题

程序还记得，有空敲上来。

将两个有序数组合并

这个就是归并的最后一步嘛。

用线程编程实现生产者消费者模式

首先贴上线程编程的方法

public class Drop {

// Message sent from producer

// to consumer.

private String message;

// True if consumer should wait

// for producer to send message,

// false if producer should wait for

// consumer to retrieve message.

private boolean empty = true;

public synchronized String take() {

// Wait until message is

// available.

while (empty) {

try {

wait();

} catch (InterruptedException e) {}

}

// Toggle status.

empty = true;

// Notify producer that

// status has changed.

notifyAll();

return message;

}

public synchronized void put(String message) {

// Wait until message has

// been retrieved.

while (!empty) {

try {

wait();

} catch (InterruptedException e) {}

}

// Toggle status.

empty = false;

// Store message.

this.message = message;

// Notify consumer that status

// has changed.

notifyAll();

}

}

import java.util.Random;

public class Producer implements Runnable {

private Drop drop;

public Producer(Drop drop) {

this.drop = drop;

}

public void run() {

String importantInfo[] = {

"Mares eat oats",

"Does eat oats",

"Little lambs eat ivy",

"A kid will eat ivy too"

};

Random random = new Random();

for (int i = 0;

i < importantInfo.length;

i++) {

drop.put(importantInfo[i]);

try {

Thread.sleep(random.nextInt(5000));

} catch (InterruptedException e) {}

}

drop.put("DONE");

}

}

import java.util.Random;

public class Consumer implements Runnable {

private Drop drop;

public Consumer(Drop drop) {

this.drop = drop;

}

public void run() {

Random random = new Random();

for (String message = drop.take();

! message.equals("DONE");

message = drop.take()) {

System.out.format("MESSAGE RECEIVED: %s%n", message);

try {

Thread.sleep(random.nextInt(5000));

} catch (InterruptedException e) {}

}

}

}

public class ProducerConsumerExample {

public static void main(String[] args) {

Drop drop = new Drop();

(new Thread(new Producer(drop))).start();

(new Thread(new Consumer(drop))).start();

}

}