Hello,
The code below is meant to take an arraylist of product objects as an input, spun thread for each product(and add
the product to
the arraylist 'products'), check product image(product.imageURL) availability, remove
the products without images(remove
the product from
the arraylist 'products'), and return an arraylist of products with image available.
package com.catgen.thread;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.catgen.Product;
import com.catgen.Utils;
public class ProductFilterThread extends Thread{
private Product product;
private List<Product> products = new ArrayList<Product>();
public ProductFilterThread(){
}
public ProductFilterThread(Product product){
this.product = product;
}
public synchronized
void addProduct(Product product){
System.out.println("Before add: "+getProducts().size());
getProducts().add(product);
System.out.println("After add: "+getProducts().size());
}
public synchronized
void removeProduct(Product product){
System.out.println("Before rem: "+getProducts().size());
getProducts().remove(product);
System.out.println("After rem: "+getProducts().size());
}
public synchronized List<Product> getProducts(){
return this.products;
}
public synchronized
void setProducts(List<Product> products){
this.products = products;
}
public
void run(){
boolean imageExists = Utils.fileExists(this.product.ImageURL);
if(!imageExists){
System.out.println(this.product.ImageURL);
removeProduct(this.product);
}
}
public List<Product> getProductsWithImageOnly(List<Product> products){
ProductFilterThread pft = null;
try{
List<ProductFilterThread> threads = new ArrayList<ProductFilterThread>();
for(Product product: products){
pft = new ProductFilterThread(product);
addProduct(product);
pft.start();
threads.add(pft);
}
Iterator<ProductFilterThread> threadsIter = threads.iterator();
while(threadsIter.hasNext()){
ProductFilterThread thread = threadsIter.next();
thread.join();
}
}catch(Exception e){
e.printStackTrace();
}
System.out.println("Total returned products = "+getProducts().size());
return getProducts();
}
}
Calling statement:
displayProducts = new ProductFilterThread().getProductsWithImageOnly(displayProducts);
Here, when addProduct(product) is called from within getProductsWithImageOnly(), getProducts() returns
the list of products, but that's not
the case(no products are returned) when
the method removeProduct() is called by a thread, because of which
the products without images are never removed. As a result, all
the products are returned by
the module whether or not
the contained products have images.
What can be
the problem here?
Thanks in advance.
James.
