Replace constructor with builder

The Replace Constructor with Builder refactoring helps hide a constructor, replacing its usages with the references to a newly generated builder class, or to an existing builder class.

Place the caret at the constructor invocation in the editor and press Alt+Enter.
From the list of available context actions, select Replace constructor with builder.
In the dialog that opens, if you need, change the suggested setter names. Specify whether you want to initialize the generated fields in the builder.
If you specify an initial value that matches the parameter value in the constructor invocation, you can skip setter method for such parameter by selecting the Optional Setter checkbox. You can also specify whether you want to create a new or use the existing builder.
Preview and apply the changes.

Example

                class Foo {
                    Foo(String firstName, String lastName, int age, boolean married) {}

                    public static void main(String[] args) {
                        Foo joe = new Foo("Joe", "Smith", 42, false);
                    }
                }
            

                class Foo {
                    Foo(String firstName, String lastName, int age, boolean married) {
                    }

                    public static void main(String[] args) {
                        //married is omitted, default "false" is used
                        Foo joe = new FooBuilder()
                        .setFirstName("Joe")
                        .setLastName("Smith")
                        .setAge(42)
                        .createFoo();
                    }

                    static class FooBuilder {
                        private String firstName;
                        private String firstName;
                        private int age;
                        private boolean married;

                        public FooBuilder setFirstName(String firstName) {
                            this.firstName = firstName;
                            return this;
                        }

                        public Foo createFoo() {
                            return new Foo(firstName, lastName, age, married);
                        }
                    }
                }
            

Replace constructor with builder dialog

Use this dialog to specify options for the Replace constructor with builder refactoring.

Item	Description

Parameter	This column shows the list of parameters detected in the constructor, which will be replaced with the builder fields.
Field name	This editable column shows the list of suggested field names in the builder.
Setter name	This editable column shows the list of suggested setter names in the builder.
Default value	Use this editable column to initialize the fields with the default values.
Optional setter	If the specified default value of a field matches the parameter value in the constructor invocation, then selecting this checkbox results in omitting setter method for this field in the builder invocation. If this checkbox is not selected, the corresponding setter method will be shown anyway.

Create new	Click this option to generate a new builder class, with the specified name and destination package.
Builder class name	This editable field shows the suggested name of the new builder class to ge generated. You can accept the default, or type a new one.
Package for new builder	Type the name of the destination package, or click the browse button, and locate it in the Choose Destination Package dialog. If the desired package doesn't exist, click to create a new one.
Use existing	Click this option to specify an existing builder class.
Builder class name	Type here the fully qualified name of the desired builder class that already exists in your project, or click the browse button and find it either by name, or in the project tree view.

Last modified: 11 February 2024