阅读以下程序: import java.io.*; publiic class Test { public static void main(String args[]) { AB s = new AB("Hello!","I love Java."); System.out.println( s.toString() ); } } class AB { String sl; String s2; AB( String strl, String str2 ) { sl = str1; s2 = str2; } public String toString() { return sl + s2; } } 该程序的输出结果是: