As Katalon has been built on top of Eclipse. It should be able to able to execute .java files and i am able to do so by Running it as a Groovy Script.
But the same is not Possible if the Test Case is a part part of a Test Suite.
Following is the error:
java.lang.IllegalArgumentException: No main method for test case: Test Cases/New Test Case
java.lang.IllegalArgumentException: No main method for test case: Test Cases/New Test Case at com.kms.katalon.core.main.TestCaseMethodNodeCollector.(TestCaseMethodNodeCollector.java:45)
at com.kms.katalon.core.main.TestCaseExecutor.processScriptPreparationPhase(TestCaseExecutor.java:124)
at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:175)
at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:72)
at com.kms.katalon.core.main.TestCaseMain$runTestCase$1.call(Unknown Source)
at TempTestSuite1515145166573.runTestCase_0(TempTestSuite1515145166573.groovy:18)
at TempTestSuite1515145166573$_run_closure1.doCall(TempTestSuite1515145166573.groovy:47)
at TempTestSuite1515145166573.run(TempTestSuite1515145166573.groovy:46)