create index from file at startup

src/main/java/cc/javastudio/raw/FileHandler.java

@@ -18,9 +18,9 @@ public class FileHandler implements Closeable {
                     String description) throws IOException {
         //position pointer at the end of file
 
-        long currentInsertPosition = dbFile.length();
-        Index.getInstance().add(currentInsertPosition);
-        dbFile.seek(currentInsertPosition);
+        long bytePosition = dbFile.length();
+        Index.getInstance().add(bytePosition);
+        dbFile.seek(bytePosition);
         /*
         calculate the total length of the record
         to put a pointer at the beginning of the record how long the record is
@@ -96,6 +96,28 @@ public class FileHandler implements Closeable {
         }
         return rawData;
     }
+    /*
+    loadIndex method creates the index contents at the startup of program
+    if file doesnt exist, does nothing
+    if file already exists, reads every recordlength and moves byteposition to end
+     */
+    public void loadIndex() throws IOException {
+        if (dbFile.length()==0){
+            return;
+        }
+        long bytePos = 0;
+        while (bytePos < dbFile.length()){
+            dbFile.seek(bytePos);
+            boolean isDeleted = dbFile.readBoolean();
+            if (!isDeleted){
+                Index.getInstance().add(bytePos);
+                bytePos += BYTE_LENGTH;
+                int recordLength = dbFile.readInt();
+                bytePos += INT_LENGTH + recordLength;
+
+            }
+        }
+    }
 
     public void close() throws IOException {
         dbFile.close();

src/main/java/cc/javastudio/testapp/TestAPP.java

@@ -9,12 +9,13 @@ import java.io.IOException;
 public class TestAPP {
     public static void main(String[] args)  {
         try (FileHandler fh = new FileHandler("DBServer.db")){
+            fh.loadIndex();
             fh.add("Johñ Doe", 44, "Berlin", "CCC-404", "Blue VW Beetle");
             fh.add("Jane Doe", 35, "USA", "CCC-404", "Seat Mottig");
             Person person = fh.readRow(1);
             System.out.println(person);
-            Index index = Index.getInstance();
-            System.out.println(index);
+            //Index index = Index.getInstance();
+            //System.out.println(index);
         } catch (IOException e) {
             e.printStackTrace();
         }