instanceof
;Class.isInstance(Object obj);
Class.isAssignableFrom(Class<?> cls);
/**
* Determines if the specified {@code Object} is assignment-compatible
* with the object represented by this {@code Class}. This method is
* the dynamic equivalent of the Java language {@code instanceof}
* operator. The method returns {@code true} if the specified
* {@code Object} argument is non-null and can be cast to the
* reference type represented by this {@code Class} object without
* raising a {@code ClassCastException.} It returns {@code false}
* otherwise.
*
* <p> Specifically, if this {@code Class} object represents a
* declared class, this method returns {@code true} if the specified
* {@code Object} argument is an instance of the represented class (or
* of any of its subclasses); it returns {@code false} otherwise. If
* this {@code Class} object represents an array class, this method
* returns {@code true} if the specified {@code Object} argument
* can be converted to an object of the array class by an identity
* conversion or by a widening reference conversion; it returns
* {@code false} otherwise. If this {@code Class} object
* represents an interface, this method returns {@code true} if the
* class or any superclass of the specified {@code Object} argument
* implements this interface; it returns {@code false} otherwise. If
* this {@code Class} object represents a primitive type, this method
* returns {@code false}.
*
* @param obj the object to check
* @return true if {@code obj} is an instance of this class
*
* @since JDK1.1
*/
public native boolean isInstance(Object obj);
/**
* Determines if the class or interface represented by this
* {@code Class} object is either the same as, or is a superclass or
* superinterface of, the class or interface represented by the specified
* {@code Class} parameter. It returns {@code true} if so;
* otherwise it returns {@code false}. If this {@code Class}
* object represents a primitive type, this method returns
* {@code true} if the specified {@code Class} parameter is
* exactly this {@code Class} object; otherwise it returns
* {@code false}.
*
* <p> Specifically, this method tests whether the type represented by the
* specified {@code Class} parameter can be converted to the type
* represented by this {@code Class} object via an identity conversion
* or via a widening reference conversion. See <em>The Java Language
* Specification</em>, sections 5.1.1 and 5.1.4 , for details.
*
* @param cls the {@code Class} object to be checked
* @return the {@code boolean} value indicating whether objects of the
* type {@code cls} can be assigned to objects of this class
* @exception NullPointerException if the specified Class parameter is
* null.
* @since JDK1.1
*/
public native boolean isAssignableFrom(Class<?> cls);
isAssignableFrom()方法是从类继承的角度去判断,instanceof关键字是从实例继承的角度去判断。
isAssignableFrom()方法是判断是否为某个类的父类,instanceof关键字是判断是否某个类的子类。
父类.class.isAssignableFrom(子类.class)
子类实例 instanceof 父类类型