另一个选项是instanceof:

Object o =...
if (o instanceof Number) {
  double d = ((Number)o).doubleValue(); //this cast is safe
}

instanceof工作在实例上，即对象上。有时您希望直接使用类。在这种情况下，您可以使用Class类的asSubClass方法。 一些例子:

1)

    Class o=Object.class;
    Class c=Class.forName("javax.swing.JFrame").asSubclass(o);

这将顺利通过，因为JFrame是对象的子类。c将包含一个表示JFrame类的Class对象。

2)

    Class o=JButton.class;
    Class c=Class.forName("javax.swing.JFrame").asSubclass(o);

这将启动java.lang.ClassCastException，因为JFrame不是JButton的子类。C将不会被初始化。

3)

    Class o=Serializable.class;
    Class c=Class.forName("javax.swing.JFrame").asSubclass(o);

这将顺利进行，因为JFrame实现了java.io.Serializable接口。c将包含一个表示JFrame类的Class对象。

当然，必须包括所需的进口。

/ /继承

    class A {
      int i = 10;
      public String getVal() {
        return "I'm 'A'";
      }
    }

    class B extends A {
      int j = 20;
      public String getVal() {
        return "I'm 'B'";
      }
    }

    class C extends B {
        int k = 30;
        public String getVal() {
          return "I'm 'C'";
        }
    }

/ /方法

    public static boolean isInheritedClass(Object parent, Object child) {
      if (parent == null || child == null) {
        return false;
      } else {
        return isInheritedClass(parent.getClass(), child.getClass());
      }
    }

    public static boolean isInheritedClass(Class<?> parent, Class<?> child) {
      if (parent == null || child == null) {
        return false;
      } else {
        if (parent.isAssignableFrom(child)) {
          // is child or same class
          return parent.isAssignableFrom(child.getSuperclass());
        } else {
          return false;
        }
      }
    }

//测试代码

    System.out.println("isInheritedClass(new A(), new B()):" + isInheritedClass(new A(), new B()));
    System.out.println("isInheritedClass(new A(), new C()):" + isInheritedClass(new A(), new C()));
    System.out.println("isInheritedClass(new A(), new A()):" + isInheritedClass(new A(), new A()));
    System.out.println("isInheritedClass(new B(), new A()):" + isInheritedClass(new B(), new A()));


    System.out.println("isInheritedClass(A.class, B.class):" + isInheritedClass(A.class, B.class));
    System.out.println("isInheritedClass(A.class, C.class):" + isInheritedClass(A.class, C.class));
    System.out.println("isInheritedClass(A.class, A.class):" + isInheritedClass(A.class, A.class));
    System.out.println("isInheritedClass(B.class, A.class):" + isInheritedClass(B.class, A.class));

/ /结果

    isInheritedClass(new A(), new B()):true
    isInheritedClass(new A(), new C()):true
    isInheritedClass(new A(), new A()):false
    isInheritedClass(new B(), new A()):false
    isInheritedClass(A.class, B.class):true
    isInheritedClass(A.class, C.class):true
    isInheritedClass(A.class, A.class):false
    isInheritedClass(B.class, A.class):false

除了@To-kra的回答。如果有人不喜欢递归:

    public static boolean isSubClassOf(Class<?> clazz, Class<?> superClass) {
        if(Object.class.equals(superClass)) {
            return true;
        }

        for(; !Object.class.equals(clazz); clazz = clazz.getSuperclass()) {
            if(clazz.getSuperclass().equals(superClass)) {
                return true;
            }
        }

        return false;
    }

注意:没有空检查的清晰度。

一个递归方法来检查Class<?>是另一个class <?>…

@To Kra的回答的改进版本:

protected boolean isSubclassOf(Class<?> clazz, Class<?> superClass) {
    if (superClass.equals(Object.class)) {
        // Every class is an Object.
        return true;
    }
    if (clazz.equals(superClass)) {
        return true;
    } else {
        clazz = clazz.getSuperclass();
        // every class is Object, but superClass is below Object
        if (clazz.equals(Object.class)) {
            // we've reached the top of the hierarchy, but superClass couldn't be found.
            return false;
        }
        // try the next level up the hierarchy.
        return isSubclassOf(clazz, superClass);
    }
}

另一个选项是instanceof:

Object o =...
if (o instanceof Number) {
  double d = ((Number)o).doubleValue(); //this cast is safe
}