Is it possible to use the instanceof operator in a switch statement?

Question

I have a question of using switch case for instanceof object:

For example: my problem can be reproduced in Java:

if(this instanceof A)     doA(); else if(this instanceof B)     doB(); else if(this instanceof C)     doC(): 

How would it be implemented using switch...case?

Answer 1

This is a typical scenario where subtype polymorphism helps. Do the following

interface I {   void do(); }  class A implements I { void do() { doA() } ... } class B implements I { void do() { doB() } ... } class C implements I { void do() { doC() } ... } 

Then you can simply call do() on this.

If you are not free to change A, B, and C, you could apply the visitor pattern to achieve the same.

Answer 2

if you absolutely cannot code to an interface, then you could use an enum as an intermediary:

public A() {      CLAZZ z = CLAZZ.valueOf(this.getClass().getSimpleName());     switch (z) {     case A:         doA();         break;     case B:         doB();         break;     case C:         doC();         break;     } }   enum CLAZZ {     A,B,C;  }