Sample java program using abstraction

Your message has been sent to W3Schools. W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning.

Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use , cookie and privacy policy. Copyright by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3. What is Abstraction in Java? What is Abstract Class? What are Abstract Methods?

Report a Bug. Previous Prev. Next Continue. Home Testing Expand child menu Expand. SAP Expand child menu Expand. Web Expand child menu Expand. Must Learn Expand child menu Expand. Big Data Expand child menu Expand. Live Project Expand child menu Expand. AI Expand child menu Expand.

Toggle Menu Close. The idea is that such changes are not supposed to have any impact on client code since they involve no difference in abstract behavior.

Software is essentially a collection of numerous statements written in any programming language. Most of the time, statements are similar and repeated over places multiple times.

Control abstraction is the process of identifying all such statements and expose them as a unit of work. We normally use this feature when we create a function to perform any work. There are chances that you will come up with the following information. You might have used ATM machines many times for cash withdrawal and bank statements. The ATM Machine has given a card swipe slot, a touch screen, and a keyboard, you can use these features to withdraw the money but you never know what exact actions or operations takes place internally in the machine-like after a card swipe the machine checks whether the card is valid or not, then the PIN will be verified if it is correct then only we can withdraw the money but the withdraw money should not be greater than the available balance.

Let us implement the above-discussed example using java. The following is our ATMMachine class and if you further notice, here we declared each and every method as public. As you can see, in the above code, now the user of our ATMMachine class can call the methods and perform the necessary actions as shown in the below code.

As you can see in the above image, you get the output as expected. Now, let us move and analyze the code. Do, we really need to call the following three methods manually. The way we have implemented the code in our ATMMachine class if the withdrawal amount is less than the available balance, then also it is going to perform the withdrawal operation.

At the same time, the user of the ATMMachine class may forget to call some of the methods as shown in the below code. Why this is happening?