Convert DAOs to proper singleton format

1 files changed, 11 insertions, 2 deletions

diff --git a/src/main/java/design/persistence/JSONPersonalDatabase.java b/src/main/java/design/persistence/JSONPersonalDatabase.java
index db613d9..70aa1ab 100644
--- a/src/main/java/design/persistence/JSONPersonalDatabase.java
+++ b/src/main/java/design/persistence/JSONPersonalDatabase.java
@@ -23,11 +23,20 @@ import java.util.Map;
 
 public class JSONPersonalDatabase implements PersonalDatabase {
 
+    private static JSONPersonalDatabase INSTANCE;
+
+    public static JSONPersonalDatabase instance() {
+        if (INSTANCE == null) {
+            INSTANCE = new JSONPersonalDatabase("data/personaldb.json");
+        }
+        return INSTANCE;
+    }
+
     private final Map<String, Golfer> cache;
     private final ObjectMapper mapper;
     private final File file;
 
-    public JSONPersonalDatabase(String filename) {
+    private JSONPersonalDatabase(String filename) {
         this.file = new File(filename);
         this.cache = new HashMap<>();
         this.mapper = new ObjectMapper();
@@ -101,7 +110,7 @@ public class JSONPersonalDatabase implements PersonalDatabase {
     }
 
     private static class CourseIdDeserializer extends JsonDeserializer<Course> {
-        MasterDatabase masterDB = MasterDatabase.INSTANCE;
+        MasterDatabase masterDB = MasterDatabase.instance();
 
         @Override
         public Course deserialize(JsonParser p, DeserializationContext context) throws IOException {