implemented Flight Repository methods

src/main/java/hs/fulda/de/ci/exam/project/FlightRepository.java

@@ -1,5 +1,32 @@
 package hs.fulda.de.ci.exam.project;
 
-public interface FlightRepository {
-    void save(Flight flight);
+import java.io.*;
+import java.util.Scanner;
+
+public class FlightRepository {
+    boolean save(Flight flight) throws IOException {
+        FileWriter fw = new FileWriter("flights.txt", true);
+        BufferedWriter bw = new BufferedWriter(fw);
+        bw.write(flight.toString());
+        bw.newLine();
+        bw.close();
+        return true;
+    };
+    String findFlightByFlightNumber(String flightNumber){
+        File file = new File("flights.txt");
+
+        try {
+            Scanner scanner = new Scanner(file);
+
+            while (scanner.hasNextLine()) {
+                String line = scanner.nextLine();
+                if(line.matches("(.*)"+flightNumber+"(.*)")) {
+                    return line;
+                }
+            }
+        } catch(FileNotFoundException e) {
+            System.out.println("There are no flights added yet. Please add a flight");
+        }
+        return "";
+    }
 }