Q:

How to write the positive and Negative test cases of same scenario in java? 

I want to write the both test cases whether positive scenario and negative scenario. 
My sample code is,
    /**
     * 
     */
    public void testgetAsnAccuracyInstanceType() throws Exception
    {
        String METHOD_NAME = "testgetAsnAccuracyInstanceType";
        log.entering(CLASS_NAME, METHOD_NAME);

         //Rating Element "1" ASN Accuracy
         populateForTestMethodValues("1");
         populateWeekOfList();
         List<WeeklyDeliveryInstanceTypeQO> asnAccuracyInstanceTypeList = weeklyDlvyInstancesDashboardReportForm.getAsnAccuracyInstanceType();
         assertTrue("testgetASNAccuracyRatingElement is Not Empty: ", asnAccuracyInstanceTypeList.size() > 0);
         log.exiting(CLASS_NAME, METHOD_NAME);
    }

A:

How about this? 
To assert it works:
// use input data you expect results for
assertFalse("testgetASNAccuracyRatingElement is empty", 
    asnAccuracyInstanceTypeList.isEmpty());

To assert the negative case:
// use input data you don't expect results for
assertTrue("testgetASNAccuracyRatingElement is not empty", 
    asnAccuracyInstanceTypeList.isEmpty());

