Java: Priority
What is the result of 2 + 2 * 2?
It's 6.
If you thought it's 8, then this lesson is for you ;-) In primary school you've learned about operation priority. Priority defines the order of operations in complex expressions. For example, multiplication and division have higher priority than addition or division. So, 2 + 3 * 2 is 8.
But sometimes we want different, non-standard order. Just like in math, we can use brackets to change the order, like so: (2 + 2) * 2.
Here are few more examples:
System.out.println(3 * (4 - 2)); // => 6
System.out.println(7 * 3 + (4 / 2) - (8 + (2 - 1))); // => 14
Be sure to pair all the brackets in correct order. This is often the problem for both beginners and experienced programmers alike. To make things easier, put both opening and closing brackets, and then type the stuff inside. The editor on our website (and most code editors) do that by default automatically: you type (, and the editor adds ). This works for some other symbols, like quotation marks, for example. We'll talk about them later.
Sometimes an expression is too complication to understand visually. Feel free to put brackets even if then won't change the priority, but will make things clearer:
Before:
System.out.println(8 / 2 + 5 - -3 / 2); // => 11
After:
System.out.println(((8 / 2) + 5) - (-3 / 2)); // => 11
Remember: code is for people, because it'll be read by people, and machines will only execute it. The only thing that matters for the machines is the correctness of code. They don't distinguish between "clear" or "confusing".
https://replit.com/@hexlet/java-basics-arithmetics
Instructions
Consider an expression: 70 * 3 + 4 / 8 + 2.
Place the brackets correctly, so that both additions (3 + 4 и 8 + 2) are calculated first. Print the result onto the screen.
The exercise doesn't pass checking. What to do? 😶
If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:
- Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨
Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.
My code is different from the teacher's one 🤔
It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.
In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.
I've read the lessons but nothing is clear 🙄
It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.
By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.