CODEWITHSUNDEEP
java
Bom Tomdabil
Bom Tomdabil

Reputation: 61

Is there a way to tell if there is code not being used in java?

Whenever I program, I seem to accumulate a lot of "trash" code, code that is not in use anymore. Just to keep my code neat, and to avoid making any expensive and unnecessary computations, Is there an easy way to tell if there is code that is not being used?

Upvotes: 0

Views: 824

Answers (6)

Marcino
Marcino

Reputation: 1

I do imagine situation when you have app developed by years and some part of your functions doesn't used anymore even they still working. Example: Let's assume you make some changes on internal systems when specific event occured but it is not occurs anymore.

I would say you could use AspectJ to obtain such data / log and then analyze after some time.

Upvotes: 0

Bathsheba
Bathsheba

Reputation: 234635

It's difficult to do in Java since it's a reflective language. (You can't simply hunt for calls to a certain class or function, for example, since reflection can be used to call a function using strings that can only be resolved at runtime.)

So in full generality, you cannot be certain.

If you have adequate unit tests for your code base then the possibility of redundant code should not be a cause for concern.

Upvotes: 1

Sweeper
Sweeper

Reputation: 270770

I think "unused code" means the code that is always not executed at runtime. I hope I interpreted you correctly.

The way to do a simple check on this is very easy. Just use IntelliJ IDEA to write your code. It will tell you that parts of your code that will never be executed and also the parts where the code can be simplified. For example,

if (x == 5) {

}

And then it will tell you that this if statement is redundant. Or if you have this:

return;
someMethod();

The IDE will tell you that someMethod() can never be reached. And it also provides a lot of other cool features.

But sometimes this isn't enough. What if you have

if (x == 5) {
    someMethod();
}

But actually in your code, x can only be in the range of 1 to 4? The IDE won't tell you about this. You can use a tool that shows your code coverage by running lots of tests. Then you can see which part of your code is not executed.

If you don't want to use such a tool, you can put breakpoints in your methods. Then run some tests by hand. When the debugger steps through your code, you can see exactly where the code goes and exactly which piece(s) of code is not executed.

Another method to do this is to use the Find/Replace function of the IDE. Check if some of your public/private methods are not being called anywhere. For example, to check whether someMethod() is called, search for someMethod in the whole project and see if there are occurrences other than the declaration.

But the most effective way would be,

Stop writing this kind of code in the first place!

Upvotes: 0

Saket
Saket

Reputation: 3129

One of the basic principles which will help you in this regard is to reduce visibility of everything as much as possible. If a class can be private don't make it default, protected or public. Same applies for methods and variables. It is much easier when you can say for sure if something is not being used outside a class. In cases like this even IDEs like Eclipse and IntelliJ Idea will suggest you about unused code.

Using this practice while developing and refactoring code is the best way to clean unused code confidently without the possibility of breaking the application. This will help in scenarios even when reflection is being used.

Upvotes: 1

Frank Puffer
Frank Puffer

Reputation: 8215

Try to avoid accumulating trash in the first place. Remove stuff you don't need anymore. (You could make a backup or better use a source code management system.)

You should also write unit tests for your functions. So you know if it still works after you remove something.

Aside from that, most IDEs will show you unused local variables and private methods.

Upvotes: 0

mvlaicevich
mvlaicevich

Reputation: 103

i think the best way to check that is to install a plugin of coverage like eclemma and create unit and integration tests to get 100% of coverage of the code that accomplish the use code/task you have. The code that don't need to be tested or don't pass over it after the tests are completed and run, is code that you are not using

Upvotes: 0

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