[java] How to obtain the last path segment of a URI

I have as input a string that is a URI. how is it possible to get the last path segment (that in my case is an id)?

This is my input URL:

String uri = "http://base_path/some_segment/id"

and I have to obtain the id I have tried with this:

String strId = "http://base_path/some_segment/id";
strId = strId.replace(path);
strId = strId.replaceAll("/", "");
Integer id =  new Integer(strId);
return id.intValue();

but it doesn't work, and surely there must be a better way to do it.

import android.net.Uri;
Uri uri = Uri.parse("http://example.com/foo/bar/42?param=true");
String token = uri.getLastPathSegment();

I know this is old, but the solutions here seem rather verbose. Just an easily readable one-liner if you have a URL or URI:

String filename = new File(url.getPath()).getName();

Or if you have a String:

String filename = new File(new URL(url).getPath()).getName();

You can also use replaceAll:

String uri = "http://base_path/some_segment/id"
String lastSegment = uri.replaceAll(".*/", "")

System.out.println(lastSegment);

result:

id

If you are using Java 8 and you want the last segment in a file path you can do.

Path path = Paths.get("example/path/to/file");
String lastSegment = path.getFileName().toString();

If you have a url such as http://base_path/some_segment/id you can do.

final Path urlPath = Paths.get("http://base_path/some_segment/id");
final Path lastSegment = urlPath.getName(urlPath.getNameCount() - 1);

In Android

Android has a built in class for managing URIs.

Uri uri = Uri.parse("http://base_path/some_segment/id");
String lastPathSegment = uri.getLastPathSegment()

In Java 7+ a few of the previous answers can be combined to allow retrieval of any path segment from a URI, rather than just the last segment. We can convert the URI to a java.nio.file.Path object, to take advantage of its getName(int) method.

Unfortunately, the static factory Paths.get(uri) is not built to handle the http scheme, so we first need to separate the scheme from the URI's path.

URI uri = URI.create("http://base_path/some_segment/id");
Path path = Paths.get(uri.getPath());
String last = path.getFileName().toString();
String secondToLast = path.getName(path.getNameCount() - 2).toString();

To get the last segment in one line of code, simply nest the lines above.

Paths.get(URI.create("http://base_path/some_segment/id").getPath()).getFileName().toString()

To get the second-to-last segment while avoiding index numbers and the potential for off-by-one errors, use the getParent() method.

String secondToLast = path.getParent().getFileName().toString();

Note the getParent() method can be called repeatedly to retrieve segments in reverse order. In this example, the path only contains two segments, otherwise calling getParent().getParent() would retrieve the third-to-last segment.

You can use getPathSegments() function. (Android Documentation)

Consider your example URI:

String uri = "http://base_path/some_segment/id"

You can get the last segment using:

List<String> pathSegments = uri.getPathSegments();
String lastSegment = pathSegments.get(pathSegments.size - 1);

lastSegment will be id.

Get URL from URI and use getFile() if you are not ready to use substring way of extracting file.

Here's a short method to do it:

public static String getLastBitFromUrl(final String url){
    // return url.replaceFirst("[^?]*/(.*?)(?:\\?.*)","$1);" <-- incorrect
    return url.replaceFirst(".*/([^/?]+).*", "$1");
}

Test Code:

public static void main(final String[] args){
    System.out.println(getLastBitFromUrl(
        "http://example.com/foo/bar/42?param=true"));
    System.out.println(getLastBitFromUrl("http://example.com/foo"));
    System.out.println(getLastBitFromUrl("http://example.com/bar/"));
}

Output:

42
foo
bar

Explanation:

.*/      // find anything up to the last / character
([^/?]+) // find (and capture) all following characters up to the next / or ?
         // the + makes sure that at least 1 character is matched
.*       // find all following characters


$1       // this variable references the saved second group from above
         // I.e. the entire string is replaces with just the portion
         // captured by the parentheses above

I'm using the following in a utility class:

public static String lastNUriPathPartsOf(final String uri, final int n, final String... ellipsis)
  throws URISyntaxException {
    return lastNUriPathPartsOf(new URI(uri), n, ellipsis);
}

public static String lastNUriPathPartsOf(final URI uri, final int n, final String... ellipsis) {
    return uri.toString().contains("/")
        ? (ellipsis.length == 0 ? "..." : ellipsis[0])
          + uri.toString().substring(StringUtils.lastOrdinalIndexOf(uri.toString(), "/", n))
        : uri.toString();
}

If you have commons-io included in your project, you can do it without creating unecessary objects with org.apache.commons.io.FilenameUtils

String uri = "http://base_path/some_segment/id";
String fileName = FilenameUtils.getName(uri);
System.out.println(fileName);

Will give you the last part of the path, which is the id