Builder pattern with and without fields duplication

src/main/java/com/scaler/lld/design/assignments/builder/DatabaseConfigurationBuilder.java

@@ -2,5 +2,66 @@
 
 @WithBuilder
 public class DatabaseConfigurationBuilder {
+    private String databaseUrl;
+    private String username;
+    private String password;
+    private int maxConnections;
+    private boolean enableCache;
+    private boolean isReadOnly;
 
+    private DatabaseConfigurationBuilder() {
+    }
+
+    public static class Builder {
+        private String databaseUrl;
+        private String username;
+        private String password;
+        private int maxConnections;
+        private boolean enableCache;
+        private boolean isReadOnly;
+
+        public Builder() {
+        }
+
+        public DatabaseConfigurationBuilder build() {
+            DatabaseConfigurationBuilder outerClassObj = new DatabaseConfigurationBuilder();
+            outerClassObj.databaseUrl = databaseUrl;
+            outerClassObj.username = username;
+            outerClassObj.password = password;
+            outerClassObj.maxConnections = maxConnections;
+            outerClassObj.enableCache = enableCache;
+            outerClassObj.isReadOnly = isReadOnly;
+            return outerClassObj;
+        }
+
+        public Builder url(String databaseUrl) {
+            this.databaseUrl = databaseUrl;
+            return this;
+        }
+
+        public Builder username(String username) {
+            this.username = username;
+            return this;
+        }
+
+        public Builder password(String password) {
+            this.password = password;
+            return this;
+        }
+
+        public Builder maxConnections(int maxConnections) {
+            this.maxConnections = maxConnections;
+            return this;
+        }
+
+        public Builder enableCache(boolean enableCache) {
+            this.enableCache = enableCache;
+            return this;
+        }
+
+        public Builder readOnly(boolean readOnly) {
+            isReadOnly = readOnly;
+            return this;
+        }
+    }
 }

src/main/java/com/scaler/lld/design/assignments/builder/DatabaseConfigurationBuilderWithoutFieldsDuplication.java

@@ -0,0 +1,63 @@
+package com.scaler.lld.design.assignments.builder;
+
+//@WithBuilder
+public class DatabaseConfigurationBuilderWithoutFieldsDuplication {
+    private String databaseUrl;
+    private String username;
+    private String password;
+    private int maxConnections;
+    private boolean enableCache;
+    private boolean isReadOnly;
+
+    private DatabaseConfigurationBuilderWithoutFieldsDuplication() {
+    }
+
+    public static class Builder {
+        private DatabaseConfigurationBuilderWithoutFieldsDuplication instance;
+        public Builder() {
+            instance = new DatabaseConfigurationBuilderWithoutFieldsDuplication();
+        }
+
+        public DatabaseConfigurationBuilderWithoutFieldsDuplication build() {
+            //return new object instead of "instance" variable due to immutability advantage.
+            DatabaseConfigurationBuilderWithoutFieldsDuplication outerClassObj = new DatabaseConfigurationBuilderWithoutFieldsDuplication();
+            outerClassObj.databaseUrl = instance.databaseUrl;
+            outerClassObj.username = instance.username;
+            outerClassObj.password = instance.password;
+            outerClassObj.maxConnections = instance.maxConnections;;
+            outerClassObj.enableCache = instance.enableCache;
+            outerClassObj.isReadOnly = instance.isReadOnly;
+            return outerClassObj;
+        }
+
+        public Builder url(String databaseUrl) {
+            instance.databaseUrl = databaseUrl;
+            return this;
+        }
+
+        public Builder username(String username) {
+            instance.username = username;
+            return this;
+        }
+
+        public Builder password(String password) {
+            instance.password = password;
+            return this;
+        }
+
+        public Builder maxConnections(int maxConnections) {
+            instance.maxConnections = maxConnections;
+            return this;
+        }
+
+        public Builder enableCache(boolean enableCache) {
+            instance.enableCache = enableCache;
+            return this;
+        }
+
+        public Builder readOnly(boolean readOnly) {
+            instance.isReadOnly = readOnly;
+            return this;
+        }
+    }
+}

src/main/java/com/scaler/lld/design/assignments/prototype/Configuration.java

@@ -1,6 +1,6 @@
 package com.scaler.lld.design.assignments.prototype;
 
-public class Configuration {
+public class Configuration implements ClonableObject<Configuration> {
     private String themeColor;
     private Boolean autoSave;
     private String language;
@@ -46,4 +46,9 @@ public String getFontFamily() {
     public ConfigurationType getType() {
         return type;
     }
+
+    @Override
+    public Configuration cloneObject() {
+        return new Configuration(themeColor, autoSave, language, darkMode, fontSize, fontFamily, type);
+    }
 }

src/main/java/com/scaler/lld/design/assignments/prototype/ConfigurationPrototypeRegistryImpl.java

@@ -0,0 +1,28 @@
+package com.scaler.lld.design.assignments.prototype;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+public class ConfigurationPrototypeRegistryImpl implements ConfigurationPrototypeRegistry {
+    Map<ConfigurationType, Configuration> configurationRegistry = new HashMap<>();
+
+    @Override
+    public void addPrototype(Configuration user) {
+        configurationRegistry.put(user.getType(), user);
+    }
+
+    @Override
+    public Configuration getPrototype(ConfigurationType type) {
+        return configurationRegistry.get(type);
+    }
+
+    @Override
+    public Configuration clone(ConfigurationType type) {
+        Configuration configuration = getPrototype(type);
+        if(Objects.nonNull(configuration)) {
+            return configuration.cloneObject();
+        }
+        return null;
+    }
+}

src/main/java/com/scaler/lld/design/assignments/singleton/FileBasedConfigurationManagerImpl.java

@@ -1,50 +1,58 @@
 package com.scaler.lld.design.assignments.singleton;
 
+import java.util.Objects;
+
 public class FileBasedConfigurationManagerImpl extends FileBasedConfigurationManager {
 
+    private static FileBasedConfigurationManagerImpl instance;
+
+    private FileBasedConfigurationManagerImpl() {
+        super();
+    }
+
     @Override
     public String getConfiguration(String key) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'getConfiguration'");
+        return properties.getProperty(key);
     }
 
     @Override
     public <T> T getConfiguration(String key, Class<T> type) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'getConfiguration'");
+        String propertyValue = properties.getProperty(key);
+        if(propertyValue == null) {
+            return null;
+        }
+        return convert(propertyValue, type);
     }
 
     @Override
     public void setConfiguration(String key, String value) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'setConfiguration'");
+        properties.setProperty(key, value);
     }
 
     @Override
     public <T> void setConfiguration(String key, T value) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'setConfiguration'");
+        properties.setProperty(key, String.valueOf(value));
     }
 
     @Override
     public void removeConfiguration(String key) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'removeConfiguration'");
+        properties.remove(key);
     }
 
     @Override
     public void clear() {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'clear'");
+        properties.clear();
     }
 
     public static FileBasedConfigurationManager getInstance() {
-        // TODO Auto-generated method stub
-        return null;
+        if(Objects.isNull(instance)) {
+            instance = new FileBasedConfigurationManagerImpl();
+        }
+        return instance;
     }
 
     public static void resetInstance() {
-        // TODO Auto-generated method stub
+        instance = null;
     }
 
 }