Extract constant
Last modified: 10 August 2022The Extract Constant refactoring makes your source code easier to read and maintain. It also helps you avoid using hardcoded constants without any explanations about their values or purpose.
In the editor, select an expression or declaration of a variable you want to replace with a constant.
Press Ctrl+Alt+C to introduce a constant or select Refactor | Extract | Constant.
note
By default, IntelliJ IDEA uses the in-place refactoring. To use the Extract Constant dialog for the refactoring, open the Settings/Preferences dialog (Ctrl+Alt+S), go to Editor | Code Editing, and select the In modal dialogs refactoring option in the Refactorings area.
Select a name from a list that opens or type your own name and press Enter.
Alternatively, press Ctrl+Alt+C twice to open the Extract Constant dialog where you can specify the additional options for the constant such as making it
private
orpublic
, move the constant to another class, and so on.tip
Use mnemonics to quickly change visibility. For example, press Alt+V to change visibility to
private
.
Example
Let's introduce a constant for the expression "string"
that occurs twice throughout code.
public class Class {
public void method() {
ArrayList list = new ArrayList();
list.add("string");
anotherMethod("string");
}
private void anotherMethod(String string) {
}
}
IntelliJ IDEA extracts the constant and replaces the expression with the constant STRING
.
public class Class {
private static final String STRING = "string";
public void method() {
ArrayList list = new ArrayList();
list.add(STRING);
anotherMethod(STRING);
}
private void anotherMethod(String string) {
}
}
Thanks for your feedback!