单选题 阅读下段代码,class Dog {public String name;Dog(String name){this.name =name;}}public class Demo1 {public static void main(String[] args){Dog dog1 = new Dog("xiaohuang");Dog dog2 = new Dog("xiaohuang");String s1 = dog1.toString();String s2 = dog2.toString();String s3 = "xiaohuang";String s4 = "xiaohuang";}}返回值为true的是( )