Restart failed test case automatically in TestNG/Selenium - selenium

Question

I am using Selenium webdriver, in Java with TestNG to run an X amount of test cases.
What I would like, is for any test case to automatically restart (either from starting or from point of failure), as soon as it fails.
I know TestNG framework has the following method
#Override
public void onTestFailure(ITestResult tr) {
log("F");
}
but I do not know how to find out which testcase it was and then how would I restart it.

Answer 1

I wanted to see an example with actual code in it and found it here:
Restarting Test immediately with TestNg
Observe how the below tests will each be re-run once as soon as the failure happens.
import org.testng.Assert;
import org.testng.IRetryAnalyzer;
import org.testng.ITestResult;
import org.testng.annotations.Test;
public class Retry implements IRetryAnalyzer {
private int retryCount = 0;
private int maxRetryCount = 1;
public boolean retry(ITestResult result) {
if (retryCount < maxRetryCount) {
retryCount++;
return true;
}
return false;
}
#Test(retryAnalyzer = Retry.class)
public void testGenX() {
Assert.assertEquals("james", "JamesFail"); // ListenerTest fails
}
#Test(retryAnalyzer = Retry.class)
public void testGenY() {
Assert.assertEquals("hello", "World"); // ListenerTest fails
}
}

Answer 2

From testng.org
Every time tests fail in a suite, TestNG creates a file called testng-failed.xml in the output directory. This XML file contains the necessary information to rerun only these methods that failed, allowing you to quickly reproduce the failures without having to run the entirety of your tests.
If you want to rerun the test exactly after the failure you need to call the method that failed. You can get that method name from ITestResult object.
If you want to rerun all the failed test cases together, then you can give the testng-failed.xml as input xml after the first execution.