@lombok.
Builder
class Foo
{
@lombok.
Builder.
Required final String firstName
;
@lombok.
Builder.
Required final String lastName
;
@lombok.
Builder.
Required final int age
;
final String email
;
private Foo
(String firstName,
String lastName,
int age,
String email
) {
this.
firstName = firstName
;
this.
lastName = lastName
;
this.
age = age
;
this.
email = email
;
}
public static FooBuilder builder
() {
return new FooBuilder
();
}
private static class FooBuilderBase
{
private String firstName
= null;
private String lastName
= null;
private int age
= 0;
private String email
= null;
private FooBuilderBase
() {}
private FooBuilderBase
(String firstName,
String lastName,
int age,
String email
) {
this.
firstName = firstName
;
this.
lastName = lastName
;
this.
age = age
;
this.
email = email
;
}
public FooBuilder email
(String email
) {
this.
email = email
;
return this;
}
}
// builder with no value fixed
private static class FooBuilder
extends FooBuilderBase
{
private FooBuilder
() {}
public FooBuilderWithFirstName firstName
(String firstName
) {
this.
firstName = firstName
;
return new FooBuilderWithFirstName
(firstName, lastName, age, email
);
}
public FooBuilderWithLastName lastName
(String lastName
) {
this.
lastName = lastName
;
return new FooBuilderWithLastName
(firstName, lastName, age, email
);
}
public FooBuilderWithAge age
(int age
) {
this.
age = age
;
return new FooBuilderWithAge
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
// builders with one value fixed
public static class FooBuilderWithFirstName
extends FooBuilderBase
{
private FooBuilderWithFirstName
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more firstName method, so the user can't clear it
public FooBuilderWithFirstName_LastName lastName
(String lastName
) {
this.
lastName = lastName
;
return new FooBuilderWithFirstName_LastName
(firstName, lastName, age, email
);
}
public FooBuilderWithFirstName_Age age
(int age
) {
this.
age = age
;
return new FooBuilderWithFirstName_Age
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
public static class FooBuilderWithLastName
extends FooBuilderBase
{
private FooBuilderWithLastName
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more lastName method, so the user can't clear it
public FooBuilderWithFirstName_LastName firstName
(String firstName
) {
this.
firstName = firstName
;
return new FooBuilderWithFirstName_LastName
(firstName, lastName, age, email
);
}
public FooBuilderWithLastName_Age age
(int age
) {
this.
age = age
;
return new FooBuilderWithLastName_Age
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
public static class FooBuilderWithAge
extends FooBuilderBase
{
private FooBuilderWithAge
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more age method, so the user can't clear it
public FooBuilderWithFirstName_Age firstName
(String firstName
) {
this.
firstName = firstName
;
return new FooBuilderWithFirstName_Age
(firstName, lastName, age, email
);
}
public FooBuilderWithLastName_Age lastName
(String lastName
) {
this.
lastName = lastName
;
return new FooBuilderWithLastName_Age
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
// builders with two values fixed
public static class FooBuilderWithFirstName_LastName
extends FooBuilderBase
{
private FooBuilderWithFirstName_LastName
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more firstName, lastName methods, so the user can't clear it
public FooBuilderComplete age
(int age
) {
this.
age = age
;
return new FooBuilderComplete
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
public static class FooBuilderWithLastName_Age
extends FooBuilderBase
{
private FooBuilderWithLastName_Age
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more lastNam, age methods, so the user can't clear it
public FooBuilderComplete firstName
(String firstName
) {
this.
firstName = firstName
;
return new FooBuilderComplete
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
public static class FooBuilderWithFirstName_Age
extends FooBuilderBase
{
private FooBuilderWithFirstName_Age
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more firstName, age method, so the user can't clear it
public FooBuilderComplete lastName
(String lastName
) {
this.
lastName = lastName
;
return new FooBuilderComplete
(firstName, lastName, age, email
);
}
// no build method yet, because the builder doesn't have all the required info
}
// builders with three values fixed
public static class FooBuilderComplete
extends FooBuilderBase
{
private FooBuilderComplete
(String firstName,
String lastName,
int age,
String email
) {
super(firstName, lastName, age, email
);
}
// no more firstName, lastName, age methods, so the user can't clear it
// but now we have a build method
public Foo build
() {
return new Foo
(firstName, lastName, age, email
);
}
}
}
