Editing Builder pattern (section)

== Examples ==
A [[C Sharp (programming language)|C#]] example:
<syntaxhighlight lang="csharp">
/// <summary>
/// Represents a product created by the builder.
/// </summary>
public class Bicycle
{
    public Bicycle(string make, string model, string colour, int height)
    {
        Make = make;
        Model = model;
        Colour = colour;
        Height = height;
    }

    public string Make { get; set; }
    public string Model { get; set; }
    public int Height { get; set; }
    public string Colour { get; set; }
}

/// <summary>
/// The builder abstraction.
/// </summary>
public interface IBicycleBuilder
{
    Bicycle GetResult();

    string Colour { get; set; }
    int Height { get; set; }
}

/// <summary>
/// Concrete builder implementation.
/// </summary>
public class GTBuilder : IBicycleBuilder
{
    public Bicycle GetResult()
    {
        return Height == 29 ? new Bicycle("GT", "Avalanche", Colour, Height) : null;
    }

    public string Colour { get; set; }
    public int Height { get; set; }
}

/// <summary>
/// The director.
/// </summary>
public class MountainBikeBuildDirector
{
    private IBicycleBuilder _builder;

    public MountainBikeBuildDirector(IBicycleBuilder builder)
    {
        _builder = builder;
    }

    public void Construct()
    {
        _builder.Colour = "Red";
        _builder.Height = 29;
    }

    public Bicycle GetResult()
	{
		return this._builder.GetResult();
	}
}

public class Client
{
    public void DoSomethingWithBicycles()
    {
        var director = new MountainBikeBuildDirector(new GTBuilder());
        // Director controls the stepwise creation of product and returns the result.
        director.Construct();
        Bicycle myMountainBike = director.GetResult();
    }
}
</syntaxhighlight>

A Java example:<syntaxhighlight lang="java" line="1">
public class Employee {
    // Required parameters
    private final String name;
    private final int id;

    // Optional parameters
    private final String department;
    private final double salary;

    // Private constructor
    private Employee(Builder builder) {
        this.name = builder.name;
        this.id = builder.id;
        this.department = builder.department;
        this.salary = builder.salary;
    }

    // Static nested Builder class
    public static class Builder {
        private final String name;
        private final int id;

        private String department = "General";  // default value
        private double salary = 0.0;            // default value

        public Builder(String name, int id) {
            this.name = name;
            this.id = id;
        }

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

        public Builder salary(double salary) {
            this.salary = salary;
            return this;
        }

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

    @Override
    public String toString() {
        return "Employee{name='" + name + "', id=" + id +
               ", department='" + department + "', salary=" + salary + '}';
    }
}
public class Main {
    public static void main(String[] args) {
        Employee emp = new Employee.Builder("Alice", 101)
                           .department("Engineering")
                           .salary(90000.0)
                           .build();

        System.out.println(emp);
    }
}

</syntaxhighlight>The Director assembles a bicycle instance in the example above, delegating the construction to a separate builder object that has been given to the Director by the Client.