Is there a way to replace class by another one in Intellij Idea?

There is this "migrate" function. Right click in whatever class -> Refactor -> Migrate.

It's a bit annoying that you have to create a new migrate set and you can't run it from scratch. But it does exactly what you need.

You pick class or package to migrate and tell it to which class or package it should change. Press run and all usages are rewritten. Then you're free to delete the old class because there will be no usages.

EDIT: In the newer versions it isn't in the context menu anymore. Just go to the menu on top - Refactor - Migrate (or simply pres shift twice and type migrate).

Cheers!

I found it easier to use delete and rename:

1. Temporarily delete TargetClass (delete without updating usages).

2. Rename SourceClass to TargetClass (including updating usages).

3. Restore TargetClass from VCS or local history.

If you are using static methods (like your StringUtils example suggests), delegate to the new class in your previous implementation like

public static String myOldMethod(String argument) { return MyNewClass.myNewMethod(argument); } 

then select Refactor->Inline and select "All invocations and remove the method" in the option dialog. In this way you can handle method name changes and argument order changes are well.

The simplest way is to write a method mapping what you would like to inline.

Say you have a method

enum MyStringUtils { public static boolean containsAnyCase(String searchFor, String searchIn) { // something } } // calling code boolean found = MyStringUtils.containsAnyCase(find, in); 

You want to use StringUtils.containsIgnoreCase however the class name, method name and order arguments are different.

So you change the body of the method to call the desired method instead.

 public static boolean containsAnyCase(String searchFor, String searchIn) { return StringUtils.containsIgnoreCase(searchIn, searchFor); } 

Select the method and <Crtl> + <Alt> + N. This will offer to inline this method everywhere and deletes your method. Your caller now looks like

 boolean found = StringUtils.containsIgnoreCase(in, find); 

This will work even if the original class uses an import of the class, import static of the method or no import at all.

Although I am not an expert in IntelliJ I can tell you that generally in java the class loading is done sequentially. I mean the class loader is looking for classes sequentially, so if the same class presents in class path several times it will take the first version.

So, it depends on how are you running your application. If for example you are using command line like java -cp lib.jar;myapp.jar com.mycompany.Main and both lib.jar and myapp.jar contain the same class Util the lib.jar version will be used.

If you want to achieve the same effect when running from IDE try to check the project properties. Probably you can control the order of library jars relatively to your project's classes? If not, probably you can add jars to bootstrap classpath. In this case add your lib.jar to bootstrap classpath (just to work on your IDE).

Good luck.