更多 Java 基础知识方面的文章，请参见文集《Java 基础知识》
public final native Class<?> getClass()public native int hashCode()public boolean equals(Object obj)protected native Object clone() throws CloneNotSupportedExceptionpublic String toString()public final native void notify()public final native void notifyAll()public final native void wait(long timeout) throws InterruptedExceptionpublic final void wait(long timeout, int nanos) throws InterruptedExceptionpublic final void wait() throws InterruptedException-
protected void finalize()：类似于析构函数，在一个对象被真正回收之前，执行一些清理工作。
