Refactor to read/write files of graph and map data

src/main/java/GraphMLFileWriter.java

@@ -0,0 +1,35 @@
+import org.jgrapht.graph.SimpleWeightedGraph;
+import org.jgrapht.nio.dot.DOTExporter;
+import org.jgrapht.nio.graphml.GraphMLExporter;
+
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+
+public class GraphMLFileWriter {
+
+    String filename;
+    SimpleWeightedGraph graph;
+
+
+    public GraphMLFileWriter(String filename, SimpleWeightedGraph graph) {
+        if(!filename.matches(".*\\.graphml")){
+            filename = filename + ".graphml";
+        }
+        this.filename = filename;
+        this.graph = graph;
+    }
+
+    public void writeGraphToFile() {
+        try(BufferedWriter writer = Files.newBufferedWriter(Path.of(filename), StandardOpenOption.CREATE_NEW);
+        ){
+            GraphMLExporter<SimpleWeightedGraph, BufferedWriter> exporter = new GraphMLExporter<>();
+            exporter.exportGraph(graph, writer);
+        } catch(IOException ex){
+            System.out.println("Could not make new file named "+filename);
+            System.err.println(ex);
+        }
+    }
+}