Builder Design Pattern

Author: DhirajGadekar

Creational Design Pattern/BuilderDesignPattern/.vscode/settings.json

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+{
+    "java.project.sourcePaths": ["src"],
+    "java.project.outputPath": "bin",
+    "java.project.referencedLibraries": [
+        "lib/**/*.jar"
+    ]
+}

Creational Design Pattern/BuilderDesignPattern/README.md

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+## Getting Started
+
+Welcome to the VS Code Java world. Here is a guideline to help you get started to write Java code in Visual Studio Code.
+
+## Folder Structure
+
+The workspace contains two folders by default, where:
+
+- `src`: the folder to maintain sources
+- `lib`: the folder to maintain dependencies
+
+Meanwhile, the compiled output files will be generated in the `bin` folder by default.
+
+> If you want to customize the folder structure, open `.vscode/settings.json` and update the related settings there.
+
+## Dependency Management
+
+The `JAVA PROJECTS` view allows you to manage your dependencies. More details can be found [here](https://github.com/microsoft/vscode-java-dependency#manage-dependencies).

Creational Design Pattern/BuilderDesignPattern/bin/App.class

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+public class App {
+    public static void main(String[] args) {
+        
+        User user1 = User.UserBuilder.builder()
+                    .setUserId(101)
+                    .setUsername("dhirajgadekar")
+                    .setEmailId("dhirajgadekar@gmail.com")
+                    .build();
+        
+        User user2 = User.UserBuilder.builder()
+            .setUserId(102)
+            .setUsername("dhiraj")
+            .build();
+
+        User user3 = User.UserBuilder.builder()
+            .setEmailId("gadekar@gmail.com")
+            .setUsername("gadekar")
+            .setUserId(103)
+            .build();
+
+        System.out.println(user1);
+        System.out.println(user2);
+        System.out.println(user3);
+    }
+}

Creational Design Pattern/BuilderDesignPattern/bin/User$UserBuilder.class

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+class User {
+
+    private final int userId;
+    private final String username;
+    private final String emailId;
+    private User(UserBuilder buider) {
+
+        this.userId = buider.userId;
+        this.username = buider.username;
+        this.emailId = buider.emailId;
+    }
+    public int getUserId() {
+        return userId;
+    }
+    public String getUsername() {
+        return username;
+    }
+    public String getEmailId() {
+        return emailId;
+    }
+    
+    @Override
+    public String toString() {
+     
+        return this.userId + " : " + this.username + " : " +  this.emailId;
+    }
+
+    static class UserBuilder {
+
+        private int userId;
+        private String username;
+        private String emailId;
+
+        private UserBuilder() {
+
+        }
+
+        public static UserBuilder builder() {
+
+            return new UserBuilder();
+        }
+        public UserBuilder setUserId(int userId) {
+            this.userId = userId;
+            return this;
+        }
+
+        public UserBuilder setUsername(String username) {
+            this.username = username;
+            return this;
+        }
+
+        public UserBuilder setEmailId(String emailId) {
+            this.emailId = emailId;
+            return this;
+        }
+        
+        public User build() {
+
+            User user = new User(this);
+            return user;
+        }
+    }
+}