We can use instanceof keyword to get the type of an object during run time.
The instanceof operator has this general form:
obj instanceof type
class A {/*from w w w.j a v a2 s . c o m*/ } class B { } class C extends A { } class D extends A { } class InstanceOf { public static void main(String args[]) { A a = new A(); B b = new B(); C c = new C(); D d = new D(); if (a instanceof A) System.out.println("a is instance of A"); if (b instanceof B) System.out.println("b is instance of B"); if (c instanceof C) System.out.println("c is instance of C"); if (c instanceof A) System.out.println("c can be cast to A"); if (a instanceof C) System.out.println("a can be cast to C"); System.out.println(); // compare types of derived types A ob = d; // A reference to d System.out.println("ob now refers to d"); if (ob instanceof D) System.out.println("ob is instance of D"); System.out.println(); ob = c; // A reference to c System.out.println("ob now refers to c"); if (ob instanceof D) System.out.println("ob can be cast to D"); else System.out.println("ob cannot be cast to D"); if (ob instanceof A) System.out.println("ob can be cast to A"); System.out.println(); // all objects can be cast to Object if (a instanceof Object) System.out.println("a may be cast to Object"); if (b instanceof Object) System.out.println("b may be cast to Object"); if (c instanceof Object) System.out.println("c may be cast to Object"); if (d instanceof Object) System.out.println("d may be cast to Object"); } }