Java casting resulting in run-time error instead of compilation error

∟Reference Citations in 2021

∟Java casting resulting in run-time error instead of compilation error

'Type Casting Compile and Runtime Error' tutorial was cited in a pretagteam.com post in 2021.

The Type Casting Compile and Runtime Error tutorial was cited in a pretagteam.com post in 2021.

Subject: Java casting resulting in run-time error instead of compilation error
Date: 2021-10-27
Author: Pretag
Source: https://pretagteam.com/question
  /java-casting-resulting-in-runtime-error-instead-of-compilation-error

In general, that's what a cast means: it tells the compiler that even though
this assignment might fail, you're pretty certain that it won't. In exchange for
allowing the code to compile, you assume the risk of a run-time exception.,The
semantics of Java say that this must result in a run-time error. In this case
it's possible to look at the code and see that it will definitely throw an error
at runtime, but how does the compiler know that a ClassCastException isn't what
you wanted?,However, I know of no Java compiler that will do that analysis for
you. It's really only worthwhile in the simplest of cases. Instead, the behavior
is that the compiler sees the cast, and reasons that it is possible to cast a
Vehicle to a Bike, and so it allows it.,No. v is a Vehicle and it might be
possible to cast it to Bike. It's not the compiler's job to figure out the
actual runtime types of every object (especially because sometimes that's
impossible).

...

If you are trying to convert reference type to another type that is not
compatible, you will get a compiler error. Here is a simple example:

/* TypeCastingCompileError.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.util.*;
class TypeCastingCompileError {
   public static void main(String[] a) {

      // Compiler error: Casting from Integer to Long is not allowed
      Integer myInteger = new Integer(777);
      Long myLong = (Long) myInteger;
   }
}