Builder pattern code generation in IntelliJ

Use the Replace Constructor with Builder refactoring.

To use this function, click on the constructor's signature in your code, then right click and select the "Refactor" menu, then click "Replace Constructor with Builder..." to bring up the dialog box to generate the code.

I found the built-in builder pattern generation in IntelliJ to be a bit clunky for a few reasons:

1. It needs to use an existing constructor as reference.
2. It's not quickly accessible via the "Generate" menu (command+N on OS X).
3. It only generates external Builder classes. As others have mentioned, it's very common to use static inner classes when implementing the builder pattern.

The InnerBuilder plugin addresses all of these shortcomings, and requires no setup or configuration. Here's a sample Builder generated by the plugin:

public class Person {
    private String firstName;
    private String lastName;
    private int age;

    private Person(Builder builder) {
        firstName = builder.firstName;
        lastName = builder.lastName;
        age = builder.age;
    }

    public static final class Builder {
        private String firstName;
        private String lastName;
        private int age;

        public Builder() {
        }

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

        public Builder lastName(String lastName) {
            this.lastName = lastName;
            return this;
        }

        public Builder age(int age) {
            this.age = age;
            return this;
        }

        public Person build() {
            return new Person(this);
        }
    }
}

Here's how to overcome the shortcomings mentioned by Mansoor Siddiqui:

1) It needs to use an existing constructor as reference.

Which is very easy to generate. Just hit Alt + Ins on Windows to invoke Generate menu and choose Constructor.

2) It's not quickly accessible via the "Generate" menu (command+N on OS X)

Just go to Settings -> Keymap, search for Builder and assign it a shortcut of your choice (if you use this functionality very often, which is rarely the case). You can assign Alt + B for example.

Another alternative is Ctrl + Shift + A (Find Action). Start typing Builder and you'll immediately get access to the command:

You could use this shortcut for quickly getting access to any IntelliJ IDEA feature (this helps a lot when you don't remember exactly what the command is called and where to find it).

3) It only generates external Builder classes. As others have mentioned, it's very common to use static inner classes when implementing the builder pattern.

I also prefer my builders as static inner classes. Unfortunately, there is no straightforward way to do it, but it's still feasible. You just have to define the nested inner class yourself (leave it empty), and when you invoke Replace Constructor with Builder dialog, choose Use existing option and select your inner class. Works like a charm! Although, it would've been easier to make this option configurable.