HelloWorldGist.java

/**
 * Created by trent on 9/18/17.
 */

public class HelloWorldGist {

    /**
     * Concatenate a URL and an endpoint.
     *
     * In some cases, a base URL ends with '/' and an endpoint starts with '/', so
     * simply adding them will return an invalid URL:
     *
     *      'mydomain.com/' + '/user/12345' = 'mydomain.com//user/12345'
     *
     * Other times, neither the base URL end with '/' nor the endpoint starts with '/'.
     * Again, we get an invalid URL:
     *
     *      'mydomain.com' + 'user/12345' = 'mydomain.comuser/12345'
     *
     * This is a simple way to get a properly formatted URL every time.
     *
     * NOTE: If a null or empty string is passed to this method, null will be returned.
     *
     * @param baseURL The base URL
     * @param endpoint The endpoint
     * @return String - The concatenation of the base URL and the endpoint.
     */
    public static String createUrl(String baseURL, String endpoint) {

        if (baseURL == null || baseURL.isEmpty() || endpoint == null || endpoint.isEmpty()) {

            return null;
        }

        if (baseURL.endsWith("/") && endpoint.startsWith("/")) {

            return baseURL.substring(0, baseURL.length() - 1) + endpoint;
        }

        if (!baseURL.endsWith("/") && !endpoint.startsWith("/")) {

            return baseURL + "/" + endpoint;
        }

        return baseURL + endpoint;
    }

    public static void main(String[] args) {
        
        // All return a proper URL ('mydomain.com/login').
        createUrl("mydomain.com/", "/login");
        createUrl("mydomain.com", "/login");
        createUrl("mydomain.com/", "login");
        createUrl("mydomain.com", "login");
    }

}