参考：java语言规范 9.2 Interface MembersIf an interface has no direct superinterfaces, then the interface implicitly declares a public abstract member method m with signature s, return type r, and throws clause t corresponding to each public instance method m with signature s, return type r, and throws clause t declared in Object, unless a method with the same signature, same return type, and a compatible throws clause is explicitly declared by the interface. It is a compile-time error if the interface explicitly declares such a method m in the case where m is declared to be final in Object. 如果一个接口没有直接的父接口，那么，这个接口就隐含的声明了这样的一些成员方法m，这个方法是public abstract的，签名是s，返回类型是r，抛出t类型异常，与Object类中声明的public的，签名是s，返回类型是r，抛出t类型异常的方法相对应，除非，接口中明确定义了这样的方法。 如果接口明确的声明了这样的方法m，m在Object类中是final的，这将会产生编译时error。Object的public方法：public final native Class<?> getClass(); public final native void notify(); public final native void notifyAll(); public final void wait() throws InterruptedException public boolean equals(Object obj) public native int hashCode(); public String toString() protected native Object clone() throws CloneNotSupportedException; protected void finalize() throws Throwable { }也就是说，接口里面默认有equals、hashcode、toString、clone和finalize这5个方法。做了个实验，挺有意思：在eclipse里面： public interface MyInterfsace { public void toString();//compile error! The return type is incompatible with Object.toString() public void equals(Object obj);//compile error!The return type is incompatible with Object.equals(Object) public String finalize() throws Throwable;//compile OK!but:The return type is incompatible with Object.finalize(), thus this interface cannot be implemented public String hashCode();//compile error! The return type is incompatible with Object.hashCode() public String clone() throws CloneNotSupportedException;//没啥特别的反应。 } It follows that is a compile-time error if the interface declares a method with a signature that is override-equivalent (§8.4.2) to a public method of Object, but has a different return type or incompatible throws clause. 如果接口声明了一个方法，跟Object的方法构成override，但是却有不一样的返回类型或者是不兼容的异常类型，也是编译时error。
懒得多说，《深入java虚拟机》第二版第126页第六行 《The JavaTM Virtual Machine Specification》Second Edition CHAPTER 4 The class File Format 4.1 The ClassFile Structure中对于super_class标志的描述，我就复制一下内容吧： super_class For a class, the value of the super_class item either must be zero or must be a valid index into the constant_pool table. If the value of the super_class item is nonzero, the constant_pool entry at that index must be a CONSTANT_Class_info (§4.4.1) structure representing the direct superclass of the class defined by this class file. Neither the direct superclass nor any of its superclasses may be a final class. If the value of the super_class item is zero, then this class file must represent the class Object, the only class or interface without a direct superclass.For an interface, the value of thesuper_class item must always be a valid index into the constant_pool table. The constant_pool entry at that index must be a CONSTANT_Class_info structure representing the classObject.
interface I {
}
class O implements I{ } //实际上是
class O extends Object implements I{
}
而object类是所有类的父类，你知道这个就可以了，至于接口和object类有什么关系，我只能说没有什么关系。
如果接口明确的声明了这样的方法m，m在Object类中是final的，这将会产生编译时error。Object的public方法：public final native Class<?> getClass();
public final native void notify();
public final native void notifyAll();
public final void wait() throws InterruptedException
public boolean equals(Object obj)
public native int hashCode();
public String toString()
protected native Object clone() throws CloneNotSupportedException;
protected void finalize() throws Throwable { }也就是说，接口里面默认有equals、hashcode、toString、clone和finalize这5个方法。做了个实验，挺有意思：在eclipse里面：
public interface MyInterfsace {
public void toString();//compile error! The return type is incompatible with Object.toString()
public void equals(Object obj);//compile error!The return type is incompatible with Object.equals(Object)
public String finalize() throws Throwable;//compile OK!but:The return type is incompatible with Object.finalize(), thus this interface cannot be implemented
public String hashCode();//compile error! The return type is incompatible with Object.hashCode()
public String clone() throws CloneNotSupportedException;//没啥特别的反应。
}
It follows that is a compile-time error if the interface declares a method with a signature that is override-equivalent (§8.4.2) to a public method of Object, but has a different return type or incompatible throws clause.
如果接口声明了一个方法，跟Object的方法构成override，但是却有不一样的返回类型或者是不兼容的异常类型，也是编译时error。
另外，通过代码也可以验证，你把一个对象赋值给一个接口的引用，是可以调用Object中的wait，notify等方法的
把一个对象赋值给一个接口的引用UPUP
interface HYL {
void print();
}
public class HYLTest {
public static void main(String[] args) {
}
public void add(HYL i){
get(i);
}
public void get(Object ob) {
}
}看到上面的代码一定会想，接口继承了Object类，其实不然，但为什么get()中可以传入一个接口，应该接口可以定义引用，但JVM知道引用必然会指向一个子类对象，所有的对象都实现了Object类，子类对象也不例外，所以i肯定指向的是一个实现了这个接口的对象当然继承了Object ，，，个人见解（接口没有实现）
还可以这样分析：接口里面所有的方法都是抽象的未实现的方法，object里面的方法都实现了，如果接口可以继承Objct那么接口中就有非抽象的方法了，如果lz认为可以这样的话我的答案是：不能继承
《The JavaTM Virtual Machine Specification》Second Edition CHAPTER 4 The class File Format
4.1 The ClassFile Structure中对于super_class标志的描述，我就复制一下内容吧：
super_class
For a class, the value of the super_class item either must be zero or must be a valid index into the constant_pool table. If the value of the super_class item is nonzero, the constant_pool entry at that index must be a CONSTANT_Class_info (§4.4.1) structure representing the direct superclass of the class defined by this class file. Neither the direct superclass nor any of its superclasses may be a final class.
If the value of the super_class item is zero, then this class file must represent the class Object, the only class or interface without a direct superclass.For an interface, the value of the super_class item must always be a valid index into the constant_pool table. The constant_pool entry at that index must be a CONSTANT_Class_info structure representing the class Object.