Change Class Signature

The Change Class Signature refactoring lets you turn a class into a generic and manipulate its type parameters. The refactoring automatically corrects all calls, implementations and overridings of the class.

• Example
• Use cases
• Changing a class signature

Example

// This is the class whose signature will be changed:

public class MyClass {
    // some code here
}

public class MyOtherClass {

    // Here are the references to MyClass:

    MyClass myClass;
    void myMethod(MyClass myClass) {
        // some code here
    }
    // some code here
}

// Now we are going to add two formal type parameters
// to MyClass.

// Two formal type parameters have been added:

public class MyClass<Param1, Param2> {
    // some code here
}

public class MyOtherClass {

    // The references to MyClass have changed accordingly:

    MyClass<String, Integer> myClass;
    void myMethod(MyClass<String, Integer> myClass) {
        // some code here
    }
    // some code here
}

// When performing the refactoring, String and Integer
// were specified as the default values for Param1 and
// Param2 respectively.

Use cases

• The type parameters can have bounds extending other constructs including other type parameters from another class. For instance, the code like public class ClassA<T, E> can be easily transformed to public class ClassA<T, E extends T>. However, if the parameter order was initially public class ClassA<E, T>, the Change Class Signature refactoring may be useful for changing the parameter order in the class signature as well as in all its usages.
• IntelliJ IDEA can successfully deal with rather complicated cases and can alter parameters and corresponding usages if one parameter depends on another.

Changing a class signature