Had the same problem with spaces. Combination of URL and URI solved it:
URL url = new URL("file:/E:/Program Files/IBM/SDP/runtimes/base");
URI uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
* Source: https://stackoverflow.com/a/749829/435605