how to run only failed test cases in testng code example

Example: run failed test cases in testng

I would use testng-failed.xml file to execute
failed test cases
1. After the first run of an automated test run.
Right click on Project and click on Refresh

2. A folder will be generated named
“test-output” folder. Inside “test-output”
folder, you could find “testng-failed.xml”

3. Run “testng-failed.xml” to execute 
the failed test cases again. Right-click
on this file and click on run as and 
select the option called "testNG suite".