我在线程“main”java.lang中出错。在java.lang.StringBuffer NullPointerException。< init >(未知源)

In an array of strings 'a' having 'n' strings i have to select the Palin Pairs from the given strings .for ex for input 3 bba abb abb Output=2 what m i doing wrongIn an array of strings 'a' having 'n' strings i