Why Intellij IDEA is better than Eclipse?

There are "eternal" questions that have no single correct answer. E.g. what is better: Windows or Linux, Java or C#; who is stronger, IDEA or Eclipse......

One of such holywars is selection of the best Java IDE:

  

There is a lot of disputes on this topic discussing which of them has more plugins, shortkeys and so on. There is so many differences that it's difficult to decide what of them are the most important. As a result, people typically claim that both IDEs are equal in their capabilities, and choosing of one of them is a matter of taste.

 am going to show just one major differencebetween IDEA and Eclipse.

The main difference between IDEA and Eclipse

The main reason why IDEA is steeper is: IDEA feels context. That's what JetBrains employees mean when they name IDEA intelligent. What it really means? IDEA indexes the whole your project, analyses everything it has, and even builds the syntax tree.

Still not clear? Do not worry, it will become clear in the following examples.

This ability to understand the context is expressed in many, many ways, here are just a few.

1. Debugging

As a part of debugging process, we often want to evaluate some expression to see its value. In Eclipse you need to select this expression. It's important to exactly select the whole expression, otherwise Eclipse cannot evaluate it. Now you press Ctrl+Shift+I and see the value of expression.

With IDEA you don't need to select anything. You just put cursor at any place inside your expression (at method hasAttribute in given case) and press Alt+F8. IDEA understands which expression you probably need and shows a dialog window suggesting several possible variants for your expression. You can also edit and immediatelly evaluate the expression in this dialog. Very convenient! After trying this feature, you just cannot debug in Eclipse anymore. 

It turns out that both IDEs, in principle, allow you to do the same thing. But with IDEA it's much easier and faster. I'm serious, the difference is huge - it's just Heaven and Earth. In this small dialog window IDEA will provide autofilling, syntax highlighting and everything you need.

2. Autocomplete

Autocomplete is what distinguishes any IDE from the notepad. In this area feeling the context gives IDEA a qualitative advantage. For example, we started writing a line of code:

view sourceprint?

1.assertElement(By.id("errorMessage"), vi

and now we want to find what options do we have: what can start with letters "vi".

What IDEA does? Not waiting for any keystrokes, it immediatelly understands that method assertElement wants an Condition class instance as a second parameter, and there is a static variable in class Condition with name visible. And IDEA immediatelly suggests the only valid option: 

And what Eclipse does? Alas, it does not understand the context. It does not know that the cursor is located where the second parameter of the method assertElement should place. So when you press the sacred Ctrl + Space, Eclipse simply shows everything in Universe that begins with the letters "vi":

In a beautiful pop-up window we see a lot of pretty-highlighted well-documented useless information. :(

3. Refactoring

Professional programmers are able to be productive using refactorings provided by their IDE. All modern IDE offer a very impressive set of refactorings. 

For example, suppose we have a method assertErrorMessageIsHidden:

view sourceprint?

1.public void assertErrorMessageIsHidden() {

2.assertElement(By.id("errorMessage"), Condition.visible);

3.}

and we want the String "errorMessage" to come as a parameter to this method.

Let's start from IDEA. Put the cursor to any place inside the string "errorMessage", press Ctrl+Alt+P (meaning "parameter"), and IDEA suggests what expression we probably could extract to a parameter:

As soon as the expression "errorMessage" is selected, IDEA suggests several possible names for this parameter. 

Do not forget: select the entire expression "errorMessage" (always with quotes, or get a wild message "An expression must be select to activate this refactoring"), choose a refactoring "Introduce parameter" (from the menu, there is no hot key) and get about the same result. However, Eclipse doesn't suggest options for a parameter name,

 

Conclusion

If we are choosing a Java IDE then Intellij IDEA is definitely better than Eclipse. It's not just a matter of taste. IDEA is objectively better. It lets you to quickly and easily write and change the code, suggests appropriate names, finds the appropriate methods. It does not require you to exactly select the expressions, but guesses what you want to do and how you wanted to name it. IDEA anticipates and suggests.