When is casting between classes necessary

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Note: type casting is not possible for a Boolean data type. There are 13 types of conversion in Java. In this article, we will only look at 2 major types: Implicit casting. Explicit casting. Implicit casting This type of conversion is also known as widening casting. Implicit casting takes place under two conditions: Compatibility of the data types.

For example, data types such as numeric are compatible with other numeric data types, but they are not compatible with boolean, char, or string data types. In the same way as string is not compatible with a boolean data type. If the targeted value to be converted has a smaller length e. My double is About the author Terrypha Wamaitha Terrypha is an undergraduate computer science student at Meru university.

Improve this question. John Kugelman k 65 65 gold badges silver badges bronze badges. Dhivakar Dhivakar 1, 5 5 gold badges 12 12 silver badges 17 17 bronze badges. A Dog is an Animal. Most of the times upcasting is unnecessary unless you want to use a certain overloaded method. What is the output of your code?

The interesting thing is, that d. Chris both 'd' and 'a' point to the same object Add a comment. Active Oldest Votes. Maybe a Cat? Maybe an Animal? Improve this answer.

Does proper downcasting ensures no ClassCastException or not? Like in the first case? What do you mean by "proper"? Pretty much sums up everything I need to know about Casting. Down-casting and up-casting was as follows: Upcasting : When we want to cast a Sub class to Super class, we use Upcasting or widening.

Dog a. Premraj Premraj So, there is no such a way of doing upcasting to call the method's parent? Assume you have three dogs Dog - This is the super Class. Pet Dog - Pet Dog extends Dog. Community Bot 1 1 1 silver badge. Nagarjuna Yelisetty Nagarjuna Yelisetty 1 1 gold badge 6 6 silver badges 11 11 bronze badges. The mechanism used isn't specified, but the most usual mechanism -a vtable - does no such thing.

Look in the object code. No downcast. Why not? This is what happens right can you give a example where it will not work? This is what happens right.. It's your contention. It's up to you to prove it. Show where in the object code the downcast occurs. The answer to the question 'why not' is 'because it isn't necessary'. The vtable takes care of the method dispatch, and the variable already points to the entire object.

It is a mere assertion. I am asking you to prove your statements. You're not doing so. In effect you're only repeating yourself. And I have already provided several refutations. I've also provided a decision procedure. If you can find a downcast in the object code for a method call, you're right and I'm wrong.

This is how science is done. Do it. And claiming that I am 'boldly depending on the documentation' is a blatant misrepresentation. Don't do that. Show 3 more comments. Privacy Statement. Required cookies are necessary for basic website functionality. Some examples include: session cookies needed to transmit the website, authentication cookies, and security cookies. Functional cookies enhance functions, performance, and services on the website.

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