Created StockFileWriter interface and moved csv write to its own file…

… to open up for additional formats in the future

src/main/java/millions/controller/CSVStockFileWriter.java

@@ -0,0 +1,35 @@
+package millions.controller;
+
+import millions.model.Stock;
+
+import java.io.FileWriter;
+import java.util.ArrayList;
+import java.util.List;
+
+public class CSVStockFileWriter implements StockFileWriter {
+  List<Stock> stocks;
+  String finalString;
+
+  public CSVStockFileWriter(List<Stock> stocks) {
+    this.stocks = stocks;
+  }
+
+  @Override
+  public void formatString() {
+    StringBuilder builder = new StringBuilder();
+    stocks.forEach(stock -> {
+      builder.append(stock.getSymbol());
+      builder.append(",");
+      builder.append(stock.getCompany());
+      builder.append(",");
+      builder.append(stock.getLatestPriceChange().toString());
+    });
+    this.finalString = builder.toString();
+  }
+
+  @Override
+  public boolean write(){
+    // TODO: handle file creation/file selection when writing to file
+    return false;
+  }
+}

src/main/java/millions/controller/StockFileWriter.java

@@ -0,0 +1,8 @@
+package millions.controller;
+
+import java.util.List;
+
+public interface StockFileWriter {
+  public void formatString();
+  public boolean write();
+}