Proper use of URLConnection and try-with-resources in Java 8

bufferedreader, java, try-with-resources, urlconnection

Solution

All a `Reader`'s close method really does, ultimately, is close resources. (See the javadoc.) Therefore, you don't really need to close the `BufferedReader` or `InputStreamReader` if you've closed the `InputStream`. However, it is more clear that you are closing all resources, and avoids compiler warnings, if you close it anyway. Since closing a `Reader` closes all underlying `Reader`s and resources, closing the `BufferedReader` will close everything:

try (BufferedReader rd = new BufferedReader(new InputStreamReader(
        connection.getInputStream()))) {
    return new JSONObject(readAll(rd));
}

So you only need to declare the top-level reader in your try-with-resources.

Problem

I am not 100% if this code is 100% save against memory leaks or leaving sockets open: ``` public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException { URLConnection connection = new URL(url).openConnection(); connection.setReadTimeout(5000); connection.setConnectTimeout(8000); try (InputStream is = connection.getInputStream()) { BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8"))); String jsonText = readAll(rd); JSONObject json = new JSONObject(jsonText); return json; } } private static String readAll(Reader rd) throws IOException { StringBuilder sb = new StringBuilder(); int cp; while ((cp = rd.read()) != -1) { sb.append((char) cp); } return sb.toString(); } ``` Would I need to put the "BufferedReader rd" into an inner second try with too, or would it be obsolete? What if a read or connection timeout occurs, and the try isn't finished yet? Why doesnt the URLConnection have a disconnect() or close() function btw?

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