显示搜索结果 JAVA ArrayLists

Question

I am supposed to use the method exactly(all my methods have to return void)

public void searchByPriceRange(double minPrice, double maxPrice)

The method will search the ArrayList<Property> for properties where the asking price is between the minPrice and maxPrice and add each match to a local ArrayList<Property> that will then be passed to another method that has to be

displaySearchResults(ArrayList<Property> searchResults)

How would I create a local ArrayList<Property> that is accessible outside the scope of the first method?(if thats what I am supposed to do)

my instance variable and initialization of ArrayList

 private ArrayList<Property> properties = new ArrayList<Property>();

my method in AgentListing class

public void searchByPriceRange(double minPrice, double maxPrice){

    ArrayList<Property> searchResults;
    searchResults = new ArrayList<Property>();
    for (Property property : properties){
        if (property.getAskingPrice() > minPrice &&
                property.getAskingPrice() < maxPrice){


            searchResults.add(property);
           
        }
    }
}

my display method AgentListing class

public void displaySearchResults(ArrayList<Property> searchResults){


    for(Property result: searchResults) {

        System.out.println(result);
    }

}

my driver class that I am trying to access the local arraylist with

AgentListings CharlesListings = new AgentListings();

        Property one = new Property("1ListingNumber", "777 Imaginary Drive, Nowhere, British Columbia", 1.00, "Single Family", "House",
            "1.1 Acre", 2007);

    one.setNumberOfBedrooms(1);
    one.setNumberOfBathrooms(1);


    Property two = new Property("2ListingNumber", "777 Imaginary Drive, Nowhere, British Columbia", 2.00, "Single Family", "House",
            "2.2 Acre", 2007);

    two.setNumberOfBedrooms(2);
    two.setNumberOfBathrooms(3);

CharlesListings.addProperty(one);
CharlesListings.addProperty(two);

CharlesListings.searchByPriceRange(1.0, 2.0);

CharlesListings.displaySearchResults(searchResults); //searchResults is not reachable

I added the full instructions to my assignment if I am not clear

Answer 1

How would I create a local ArrayList that is accessible outside the scope of the first method?(if thats what I am supposed to do)

here:

public void searchByPriceRange(double minPrice, double maxPrice)

return a list (searchResults) instead of void...

you can define a temp variable, or just queue the returned value as param to the display method

ArrayList<Property> x = searchByPriceRange(min, max);
displaySearchResults(x);

or

displaySearchResults(searchByPriceRange(min, max));

Answer 2

searchResult is a local variable, so it's not visible outside the method it is declared in. A possible solution would be to change the signature of the searchByPriceRange method from:

public void searchByPriceRange(double minPrice, double maxPrice)

to

public List<Property> searchByPriceRange(double minPrice, double maxPrice) .

Now you can return the searchResults list, so it can be stored in a variable or passed to another method. Since you only need to pass it to the displaySearchResults method, you could write:

CharlesListings.displaySearchResults(CharlesListings.searchByPriceRange(1.0, 2.0));

Answer 3

Modify searchByPrice(...) method like this:

public ArrayList<Property> searchByPriceRange(double minPrice, double maxPrice){

    ArrayList<Property> searchResults;
    searchResults = new ArrayList<Property>();
    for (Property property : properties){
        if (property.getAskingPrice() > minPrice &&
                property.getAskingPrice() < maxPrice){

              searchResults.add(property);
        }
    }
    return searchResults;
}

Now, when it returns searchResults array, you can use the returned value as a parameter for displaySearchResults(searchResults) method. Like this:

ArrayList<Property> searchResultsList = CharlesListings.searchByPriceRange(1.0, 2.0);
CharlesListings.displaySearchResults(searchResultsList);