Java监视器和线程并发
我正在尝试构建简单的多线程应用程序。但我对Java监视器感到困惑。我有许多线程希望将其数据格式化为一个数组。例如,我有超市线程(线程的数据在txt文件中),所以第一个线程有这些产品(牛奶、奶酪、巧克力)和每个产品的国家代码1、2、3Java监视器和线程并发,java,arrays,multithreading,concurrency,Java,Arrays,Multithreading,Concurrency,我正在尝试构建简单的多线程应用程序。但我对Java监视器感到困惑。我有许多线程希望将其数据格式化为一个数组。例如,我有超市线程(线程的数据在txt文件中),所以第一个线程有这些产品(牛奶、奶酪、巧克力)和每个产品的国家代码1、2、3 SupermarketA Milk 1 Cheese 2 Chocolate 3 SupermarketB Yogurt 1 Orangle 2 Bannana 3 Tea 7 Kiwi
SupermarketA
Milk 1
Cheese 2
Chocolate 3
SupermarketB
Yogurt 1
Orangle 2
Bannana 3
Tea 7
Kiwi 9
我想格式化数组,该数组必须包含字段(国家代码和计数)
所以我的数组应该是这样的
Country_code count
1 2
2 2
3 2
7 1
9 1
代码
这是我的监视器课程
public class SingleArray {
private SortedArray[] array;
private int arrayIndex;
private static final int MAX_SIZE = 5;
public SingleArray() {
array = new SortedArray[MAX_SIZE];
arrayIndex = 0;
initArray();
}
private void initArray() {
for (int i = 0; i < MAX_SIZE; i++) {
array[i] = new SortedArray();
}
}
public synchronized void inc(){
awaitUnderMax();
notifyAll();
}
private void awaitUnderMin(){
while (arrayIndex == 0) try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void dec(){
awaitUnderMin();
notifyAll();
}
public void add(ArrayList<Integer> count){
for (int i = 0; i < count.size(); i++) {
singleArray.inc();
int num = count.get(i);
if (singleArray.arrayIndex == 0) { // if array is empty add value to it
singleArray.array[0].num = num;
singleArray.array[0].count++;
singleArray.arrayIndex++;
} else {
if (!isThere(num)) { // if num is a new value to array
singleArray.inc();
int index1 = singleArray.arrayIndex;
if (num > singleArray.array[index1 - 1].num) {
singleArray.inc();
singleArray.array[index1].num = num;
singleArray.inc();
singleArray.array[index1].count++;
singleArray.inc();
singleArray.arrayIndex++;
System.out.println(Thread.currentThread().getName() + " first " + singleArray.array[index1].num);
} else if (num < singleArray.array[index1 - 1].num) { // jei num mazesne uz paskutinia masyvo reiksme
int index = index1 - 1 < 0 ? index1 : index1 - 1;
while (index > 0 && num < singleArray.array[index].num) {
index--;
}
if (index != singleArray.arrayIndex) {
System.out.println(Thread.currentThread().getName() + " sec " + singleArray.array[index].num);
singleArray.array = addPos(singleArray.array, index + 1, num);
}
}
}
}
}
}
public boolean isThere(int number){
for(int i=0; i<singleArray.arrayIndex; i++){
singleArray.inc();
if(number == singleArray.array[i].num){
singleArray.array[i].count++;
return true;
}
}
return false;
}
private void awaitUnderMax(){
while (arrayIndex >= MAX_SIZE) try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void removeValue(int number, int howManyItems){
for(int i=0; i<arrayIndex; i++){
dec();
if(number == array[i].num){
int numberToDelete = array[i].count - howManyItems >= 0 ? howManyItems : array[i].count;
if(array[i].count >= numberToDelete){
array[i].count -= numberToDelete;
}
if(array[i].count == 0){
deleteItem(i);
}
}
if(array[i].count == 0){
deleteItem(i);
}
}
}
如何使用java已经提供的并发安全数据集 如果您希望对其进行排序,这一个看起来可能适合您:
只需像在普通集合中那样添加它我会认为
add
方法应该是同步的?正如您所提到的(这是代码的一部分,我还有其他基于county代码递减数组的线程),我建议将变量arrayIndex和array声明为volatile。synchronized
方法不能解决您的问题。但是你没有提供足够的信息,所以你可以写一个详细的答案。只有在假设的情况下,才能对代码进行改进,并向您展示实现的方法。请提供更多代码(国家/地区等)。为什么你认为synchronized
方法可以解决你的问题?你有没有检查过你是否会陷入僵局(我想你应该这样做)?是否可以为您使用另一种数据结构(例如优先级队列/堆)<代码>信号灯可以解决问题,但我们需要更多的代码。花点时间帮助我们理解,我们也会花点时间帮助你解决问题。@Elyasin我认为synchronized
metod add应该解决我的问题(但我不想这样做)因为一次只有一个线程可以写入数组,所以我也编辑了我的文章
public class SingleArray {
private SortedArray[] array;
private int arrayIndex;
private static final int MAX_SIZE = 5;
public SingleArray() {
array = new SortedArray[MAX_SIZE];
arrayIndex = 0;
initArray();
}
private void initArray() {
for (int i = 0; i < MAX_SIZE; i++) {
array[i] = new SortedArray();
}
}
public synchronized void inc(){
awaitUnderMax();
notifyAll();
}
private void awaitUnderMin(){
while (arrayIndex == 0) try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void dec(){
awaitUnderMin();
notifyAll();
}
public void add(ArrayList<Integer> count){
for (int i = 0; i < count.size(); i++) {
singleArray.inc();
int num = count.get(i);
if (singleArray.arrayIndex == 0) { // if array is empty add value to it
singleArray.array[0].num = num;
singleArray.array[0].count++;
singleArray.arrayIndex++;
} else {
if (!isThere(num)) { // if num is a new value to array
singleArray.inc();
int index1 = singleArray.arrayIndex;
if (num > singleArray.array[index1 - 1].num) {
singleArray.inc();
singleArray.array[index1].num = num;
singleArray.inc();
singleArray.array[index1].count++;
singleArray.inc();
singleArray.arrayIndex++;
System.out.println(Thread.currentThread().getName() + " first " + singleArray.array[index1].num);
} else if (num < singleArray.array[index1 - 1].num) { // jei num mazesne uz paskutinia masyvo reiksme
int index = index1 - 1 < 0 ? index1 : index1 - 1;
while (index > 0 && num < singleArray.array[index].num) {
index--;
}
if (index != singleArray.arrayIndex) {
System.out.println(Thread.currentThread().getName() + " sec " + singleArray.array[index].num);
singleArray.array = addPos(singleArray.array, index + 1, num);
}
}
}
}
}
}
public boolean isThere(int number){
for(int i=0; i<singleArray.arrayIndex; i++){
singleArray.inc();
if(number == singleArray.array[i].num){
singleArray.array[i].count++;
return true;
}
}
return false;
}
private void awaitUnderMax(){
while (arrayIndex >= MAX_SIZE) try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void removeValue(int number, int howManyItems){
for(int i=0; i<arrayIndex; i++){
dec();
if(number == array[i].num){
int numberToDelete = array[i].count - howManyItems >= 0 ? howManyItems : array[i].count;
if(array[i].count >= numberToDelete){
array[i].count -= numberToDelete;
}
if(array[i].count == 0){
deleteItem(i);
}
}
if(array[i].count == 0){
deleteItem(i);
}
}
}
public Thread[] setUpShopsBuilderThreads(){
int size = data.getSize();
ArrayList<ArrayList<String>> a = new ArrayList<>();
ArrayList<ArrayList<Integer>> b = new ArrayList<>();
ArrayList<ArrayList<Double>> c = new ArrayList<>();
Thread[] threads = new Thread[size];
for (int i = 0; i < size; i++) {
int tmp = data.getIndex(i);
int range = i + 1 < size ? data.getIndex(i + 1) : data.getWaresSize();
ArrayList<String> name = new ArrayList<>();
ArrayList<Integer> count = new ArrayList<>();
ArrayList<Double> price = new ArrayList<>();
for (int j = tmp; j < range; j++) {
name.add(data.getName(j));
count.add(data.getCount(j));
price.add(data.getPrice(j));
}
a.add(name);
b.add(count);
c.add(price);
}
procesas_1 p1 = new procesas_1(a.get(0), b.get(0), c.get(0));
procesas_2 p2 = new procesas_2(a.get(1), b.get(1), c.get(1));
procesas_3 p3 = new procesas_3(a.get(2), b.get(2), c.get(2));
procesas_4 p4 = new procesas_4(a.get(3), b.get(3), c.get(3));
procesas_5 p5 = new procesas_5(a.get(4), b.get(4), c.get(4));
Thread worker1 = new Thread(p1);
Thread worker2 = new Thread(p2);
Thread worker3 = new Thread(p3);
Thread worker4 = new Thread(p4);
Thread worker5 = new Thread(p5);
threads[0] = worker1;
threads[1] = worker2;
threads[2] = worker3;
threads[3] = worker4;
threads[4] = worker5;
return threads;
}
public static void main(String[] args) {
Starter start = new Starter();
start.read();
start.printShopsData();
start.printUserData();
Thread[] builderThreads = start.setUpShopsBuilderThreads();
for(int i=0; i<builderThreads.length; i++){
builderThreads[i].start();
}
}