阅读下列程序,请写出该程序的输出结果 import java.io.*; public class abc { public static void main(String args[ ]) { AB s = new AB("Hello!","I love JAVA."); System.out.println(s.toString( )); } } class AB { String s1; String s2; AB( String str1 , String str2 ) { s1 = str1; s2 = str2; } public String toString( ) { return s1+s2; } }