BigDecimal comparison issue in method

Question

I am trying to filter products as per price range of high and low. And this is the URL i'm testing with

http://localhost:8080/webstore/products/test?high=900&low=100

This is my Repository(ProductRepository)

public interface ProductRepository {
    List<Product> getProductsByPriceFilter(BigDecimal high, BigDecimal low);
}

This is my InMemoryProductRepository class which has raw data and this method

public List<Product> getProductsByPriceFilter(BigDecimal high, BigDecimal low){
        List<Product> productsByPriceFilter = new ArrayList<Product>();

        for(Product product : listOfProducts){
            if((product.getUnitPrice().compareTo(high) < -1) && (product.getUnitPrice().compareTo(high)== 0) && (product.getUnitPrice().compareTo(low) > 1) && (product.getUnitPrice().compareTo(low)==0)){
                productsByPriceFilter.add(product);
            }
        }
        return productsByPriceFilter;
    }

here is my service(ProductService)

public interface ProductService {
    List<Product> getProductsByPriceFilter(BigDecimal high, BigDecimal low);
}

And here is my implementation of service(ProductServiceImpl) which consist of this method

public List<Product> getProductsByPriceFilter(BigDecimal high, BigDecimal low){
        return productRepository.getProductsByPriceFilter(high, low);
    }

And finally here is my ProductController

@RequestMapping("/products/test")
    public String getProductsByPriceFilter(@RequestParam("high") BigDecimal high, @RequestParam("low") BigDecimal low, Model model){
        model.addAttribute("product", productService.getProductsByPriceFilter(high, low));
        return "products";
    }

But I'm constantly getting blank page with no data of all the data i have passed in high or low. So, i guess the problem lies with my getProductsByPriceFilter method in InMemoryProductRepository class.

The same integer can't be > -1 and == 0 at the same time. Your condition will never be true. You probably want `price.compareTo(low) >= 0 && price.compareTo(high) <= 0` — JB Nizet, Jan 10 '16 at 16:22
The condition .compareTo() < -1 is wrong. You should always compare the result of compareTo() with zero. — Oleg Estekhin, Jan 10 '16 at 16:23

score 0 · Accepted Answer · answered Jan 10 '16 at 16:26

0

The problem is over here in your comparison:

if((product.getUnitPrice().compareTo(high) < -1) && (product.getUnitPrice().compareTo(high)== 0) && (product.getUnitPrice().compareTo(low) > 1) && (product.getUnitPrice().compareTo(low)==0)){

Where you can't say high comparison result can be less than -1 and at the same time equal to zero. Instead you need is or between two conditions or better <= 0 and the other way for low like:

 if((product.getUnitPrice().compareTo(high) <= 0) && (product.getUnitPrice().compareTo(low) >= 0))

answered Jan 10 '16 at 16:26

SMA

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I fixed that but is mu controller mapping correct? Because i'am getting no data still. I am new to learning spring – user3127109 Jan 10 '16 at 16:37
I assume you are saying you re not getting any products on your web page. That seems like a different question. You should put some debug statements in and see if you are getting valid high & low values and if you are returning anything in your product List. – K.Nicholas Jan 10 '16 at 21:25

BigDecimal comparison issue in method

1 Answers1