Singleton assignment solution

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;
+
+    //step 1:hide the constructor
+    private DatabaseConfigurationBuilder(){
+
+    }
+
+    public static DBConfigBuilder BuildDBConfiguration(){
+        return new DBConfigBuilder();
+    }
+
+    public static class DBConfigBuilder{
+        private DatabaseConfigurationBuilder instance;
+
+        public DBConfigBuilder( ){
+
+            this.instance = new DatabaseConfigurationBuilder();
+        }
+
+        public DBConfigBuilder WithDatabaseUrl(String url){
+            this.instance.databaseUrl = url;
+            return this;
+        }
+
+        public DBConfigBuilder WithUsername(String usrname){
+            this.instance.username = usrname;
+            return this;
+        }
+
+        public DBConfigBuilder WithPassword(String passwd){
+            this.instance.password = passwd;
+            return this;
+        }
+
+        public DBConfigBuilder WithMaxConnections(int connections){
+            this.instance.maxConnections = connections;
+            return this;
+        }
+
+        public DBConfigBuilder enableCache(boolean canEnable){
+            this.instance.enableCache = canEnable;
+            return this;
+        }
+
+        public DBConfigBuilder isReadOnly(boolean isReadOnly){
+            this.instance.isReadOnly = isReadOnly;
+            return this;
+        }
+
+        public DatabaseConfigurationBuilder build(){
+            return instance;
+        }
+
+
+
+    }
 
 }

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

@@ -1,50 +1,65 @@
 package com.scaler.lld.design.assignments.singleton;
 
+import java.util.Optional;
+
 public class FileBasedConfigurationManagerImpl extends FileBasedConfigurationManager {
 
+    private static FileBasedConfigurationManagerImpl instance = null;
+
+    private FileBasedConfigurationManagerImpl(){
+
+    }
+
+
     @Override
     public String getConfiguration(String key) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'getConfiguration'");
+        return getProperties().getProperty(key);
     }
 
     @Override
     public <T> T getConfiguration(String key, Class<T> type) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'getConfiguration'");
+        String value = getProperties().getProperty(key);
+        Optional<String> checkNull = Optional.ofNullable(value);
+        if(checkNull.isPresent())
+            return convert(value,type);
+        else
+            return null;
     }
 
     @Override
     public void setConfiguration(String key, String value) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'setConfiguration'");
+
+        getProperties().setProperty(key,value);
     }
 
     @Override
     public <T> void setConfiguration(String key, T value) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'setConfiguration'");
+        getProperties().setProperty(key,value.toString());
     }
 
     @Override
     public void removeConfiguration(String key) {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'removeConfiguration'");
+        getProperties().remove(key);
     }
 
     @Override
     public void clear() {
-        // TODO Auto-generated method stub
-        throw new UnsupportedOperationException("Unimplemented method 'clear'");
+        getProperties().clear();
     }
 
     public static FileBasedConfigurationManager getInstance() {
-        // TODO Auto-generated method stub
-        return null;
+        if(instance == null){
+            synchronized (FileBasedConfigurationManagerImpl.class){
+                if(instance == null){
+                    instance = new FileBasedConfigurationManagerImpl();
+                }
+            }
+        }
+        return instance;
     }
 
     public static void resetInstance() {
-        // TODO Auto-generated method stub
+        instance = null;
     }
 
 }