Builder pattern with lambdas (#12)

Author: oleksandr-sh

src/com/xpinjection/java8/good/builder/Sample.java

@@ -0,0 +1,17 @@
+package com.xpinjection.java8.good.builder;
+
+/**
+ * @author Oleksandr Shkurko
+ */
+public class Sample {
+
+ public static void main(String[] args) {
+ User user = User.builder()
+ .setId(42)
+ .setName("Guest")
+ .setAge(23)
+ .build();
+
+ System.out.println(user);
+ }
+}

src/com/xpinjection/java8/good/builder/User.java

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+package com.xpinjection.java8.good.builder;
+
+import java.util.StringJoiner;
+
+/**
+ * @author Oleksandr Shkurko
+ */
+public class User {
+
+ private Long id;
+ private String name;
+ private int age;
+
+ private User(Long id, String name, int age) {
+ this.id = id;
+ this.name = name;
+ this.age = age;
+ }
+
+ public static UserBuilderId builder() {
+ return id -> name -> age -> () -> new User(id, name, age);
+ }
+
+ public Long getId() {
+ return id;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public int getAge() {
+ return age;
+ }
+
+ public interface UserBuilderId {
+ UserBuilderName setId(long id);
+ }
+
+ public interface UserBuilderName {
+ UserBuilderAge setName(String name);
+ }
+
+ public interface UserBuilderAge {
+ UserBuilder setAge(int age);
+ }
+
+ public interface UserBuilder {
+ User build();
+ }
+
+ @Override
+ public String toString() {
+ return new StringJoiner(", ", User.class.getSimpleName() + "[", "]")
+ .add("id=" + id)
+ .add("name='" + name + "'")
+ .add("age=" + age)
+ .toString();
+ }
+}

src/com/xpinjection/java8/good/builder2/Sample.java

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+package com.xpinjection.java8.good.builder2;
+
+/**
+ * @author Oleksandr Shkurko
+ */
+public class Sample {
+
+ public static void main(String[] args) {
+ User user = User.builder()
+ .setId(1)
+ .setName("guest")
+ .setAge(18)
+ .addRole("GUEST")
+ .addRole("LOGIN")
+ .build();
+
+ System.out.println(user);
+ }
+}

src/com/xpinjection/java8/good/builder2/User.java

@@ -0,0 +1,87 @@
+package com.xpinjection.java8.good.builder2;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.StringJoiner;
+
+import static java.util.Collections.unmodifiableSet;
+import static java.util.Objects.requireNonNull;
+
+/**
+ * @author Oleksandr Shkurko
+ */
+public class User {
+ private Long id;
+ private String name;
+ private int age;
+ private Set<String> roles;
+
+ private User() {
+ }
+
+ public static UserBuilderId builder() {
+ return id -> name -> age ->
+
+ new UserBuilderRoles() {
+ @Override
+ public User build() {
+ User user = new User();
+ user.id = id;
+ user.name = requireNonNull(name);
+ user.age = age;
+ user.roles = unmodifiableSet(this.roles);
+ return user;
+ }
+ };
+ }
+
+ public Long getId() {
+ return id;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public int getAge() {
+ return age;
+ }
+
+ public Set<String> getRoles() {
+ return roles;
+ }
+
+ public interface UserBuilderId {
+ UserBuilderName setId(long id);
+ }
+
+ public interface UserBuilderName {
+ UserBuilderAge setName(String name);
+ }
+
+ public interface UserBuilderAge {
+ UserBuilderRoles setAge(int age);
+ }
+
+ public static abstract class UserBuilderRoles {
+
+ Set<String> roles = new HashSet<>();
+
+ public UserBuilderRoles addRole(String role) {
+ roles.add(requireNonNull(role));
+ return this;
+ }
+
+ public abstract User build();
+ }
+
+ @Override
+ public String toString() {
+ return new StringJoiner(", ", User.class.getSimpleName() + "[", "]")
+ .add("id=" + id)
+ .add("name='" + name + "'")
+ .add("age=" + age)
+ .add("roles=" + roles)
+ .toString();
+ }
+}