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How to find an available (free) TCP port in Java

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gistfile1.java
Java
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/**
* Returns a free port number on localhost.
*
* Heavily inspired from org.eclipse.jdt.launching.SocketUtil (to avoid a dependency to JDT just because of this).
* Slightly improved with close() missing in JDT. And throws exception instead of returning -1.
*
* @return a free port number on localhost
* @throws IllegalStateException if unable to find a free port
*/
private static int findFreePort() {
ServerSocket socket = null;
try {
socket = new ServerSocket(0);
socket.setReuseAddress(true);
int port = socket.getLocalPort();
try {
socket.close();
} catch (IOException e) {
// Ignore IOException on close()
}
return port;
} catch (IOException e) {
} finally {
if (socket != null) {
try {
socket.close();
} catch (IOException e) {
}
}
}
throw new IllegalStateException("Could not find a free TCP/IP port to start embedded Jetty HTTP Server on");
}

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