[英]Issues in communication between threads
我正在嘗試解決以下問題。
編寫一個從執行開始就打印消息的程序,並使用另一個線程為每第十五條消息打印一條消息。 在打印每條消息時,使消息打印線程通知消息打印線程。 添加另一個線程,該線程每隔七個消息打印一次不同的消息,而無需修改消息打印線程。
我嘗試了以下方法。 任何人都可以指導我如何在程序中調用特定線程。
該類用於
public class Message{
String message;
volatile boolean flag=true;
synchronized void printMessage(String message){
int count=16;
for(int i=0;true;){
i++;
if(i%15==0 || i%7==0){
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(i +" "+message);
notify();
}
}
synchronized void printMessageFifteen(String message){
System.out.println(message);
notify();
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
synchronized void printMessageSeven(String message){
System.out.println(message);
notify();
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
以連續方式打印出消息的線程:
public class ContinousMessageThread extends Thread{
Message messageObject;
ContinousMessageThread(Message messageObject){
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
messageObject.printMessage(this.messageObject.message);
}
}
每十五秒鍾打印出一條消息的線程:
public class FifteenSecondsMessageThread extends Thread{
Message messageObject;
public FifteenSecondsMessageThread(Message messageObject) {
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
while(true){
messageObject.printMessageFifteen("Fifteen Seconds over");
}
}
}
每七秒鍾打印一次消息的線程
public class SevenSecondsMessageThread extends Thread {
Message messageObject;
public SevenSecondsMessageThread(Message messageObject) {
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
while(true){
messageObject.printMessageSeven("Seven Seconds over");
}
}
}
啟動所有線程的主類。
public class MainClass {
public static void main(String[] args) {
Object sevenSecond= new Object();
Object fifteenSecond= new Object();
Message messageObject= new Message();
messageObject.message="seconds";
ContinousMessageThread continousMessageThreadObject= new ContinousMessageThread(messageObject);
SevenSecondsMessageThread secondsMessageThreadObject = new SevenSecondsMessageThread(messageObject);
FifteenSecondsMessageThread fifteenSecondsMessageThreadObject=new FifteenSecondsMessageThread(messageObject);
}
我得到的輸出:
1 seconds
2 seconds
3 seconds
4 seconds
5 seconds
6 seconds
Seven Seconds over
7 seconds
8 seconds
9 seconds
10 seconds
11 seconds
12 seconds
13 seconds
Seven Seconds over
14 seconds
Seven Seconds over
15 seconds
16 seconds
17 seconds
18 seconds
19 seconds
20 seconds
Seven Seconds over
21 seconds
22 seconds
23 seconds
24 seconds
25 seconds
26 seconds
27 seconds
Seven Seconds over
Fifteen Seconds over
Seven Seconds over
28 seconds
29 seconds
Seven Seconds over
Fifteen Seconds over
30 seconds
31 seconds
32 seconds
33 seconds
34 seconds
Fifteen Seconds over
Seven Seconds over
預期結果是
1 seconds
2 seconds
3 seconds
4 seconds
5 seconds
6 seconds
Seven Seconds over
7 seconds
8 seconds
9 seconds
10 seconds
11 seconds
12 seconds
13 seconds
Seven Seconds over
14 seconds
Fifteen Seconds over
15 seconds
16 seconds
17 seconds
18 seconds
19 seconds
20 seconds
Seven Seconds over
21 seconds
22 seconds
23 seconds
24 seconds
25 seconds
26 seconds
27 seconds
Seven Seconds over
28 seconds
29 seconds
Fifteen Seconds over
30 seconds
31 seconds
32 seconds
33 seconds
34 seconds
Seven Seconds over
注意:
僅調用SevenSecondMessageThread和ContiniousMessageThread或FifteenSecondMessageThread和ContiniousMessageThread時,程序運行良好(在預期的行上)。 但是在調用所有線程時失敗。 我不明白為什么會這樣,如何避免這種情況?
為了獲得所需的行為,您可以考慮要同步的對象。 在這種情況下,我定義了兩個對象(sevenSecond和十五秒),並使這兩個對象上的連續線程同步,以便我們可以准確地定義哪個線程開始或停止。
這是代碼的修改后的版本,實現了具有不時被其他兩個中斷的連續線程的主要思想:
public static void main(String[] args){
Object sevenSecond= new Object();
Object fifteenSecond= new Object();
Message messageObject= new Message();
messageObject.message="seconds";
ContinousMessageThread continousMessageThreadObject= new ContinousMessageThread(messageObject);
SevenSecondsMessageThread secondsMessageThreadObject = new SevenSecondsMessageThread(messageObject);
FifteenSecondsMessageThread fifteenSecondsMessageThreadObject=new FifteenSecondsMessageThread(messageObject);
}
static class Message{
String message;
Object sevenLock = new Object();
Object fifteenLock = new Object();
void printMessage(String message) {
try {
for(int i=0; true; i++){
if (i % 7 == 0) {
synchronized (sevenLock) {
sevenLock.notify();
System.out.println(i + " " + message);
sevenLock.wait();
}
}
else if (i % 15 == 0) {
synchronized (fifteenLock) {
fifteenLock.notify();
System.out.println(i + " " + message);
fifteenLock.wait();
}
}
else {
System.out.println(i + " " + message);
System.out.flush();
}
if (i == 50) System.exit(-1); // stops after a few iterations
}
}
catch(InterruptedException e) {
e.printStackTrace();
}
}
void printMessageFifteen(String message) {
try {
synchronized (fifteenLock) {
System.out.println(message);
fifteenLock.notify();
fifteenLock.wait();
}
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
synchronized void printMessageSeven(String message) {
try {
synchronized (sevenLock) {
System.out.println(message);
sevenLock.notify();
sevenLock.wait();
}
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
static class ContinousMessageThread extends Thread {
Message messageObject;
ContinousMessageThread(Message messageObject){
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
messageObject.printMessage(this.messageObject.message);
}
}
static class FifteenSecondsMessageThread extends Thread{
Message messageObject;
public FifteenSecondsMessageThread(Message messageObject) {
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
while(true){
messageObject.printMessageFifteen("Fifteen Seconds over");
}
}
}
static class SevenSecondsMessageThread extends Thread {
Message messageObject;
public SevenSecondsMessageThread(Message messageObject) {
this.messageObject=messageObject;
new Thread(this,"seconds").start();
}
@Override
public void run() {
while(true){
messageObject.printMessageSeven("Seven Seconds over");
}
}
}
請注意,與您的版本一樣,兩個線程(7和15)第一次輸出其消息與連續線程無關(它們可以出現在0到7或15之間的任何位置)。 從第二開始,他們就擁有了期望的行為。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.