Plum average yield calculation task ready

src/DataTableModel.java

@@ -149,6 +149,30 @@ public class DataTableModel extends AbstractTableModel {
         return targetPos;
     }
 
+    public double getPlumHarvestAvg() {
+        double harvest = 0;
+        int counter = 0;
+
+        for (int row = 0; row < getRowCount(); row++) {
+            for (int col = 0; col < getColumnCount(); col++) {
+                Data cell = rowData[row][col];
+                // Check if cell contains plum tree
+                if (cell.getTree().equals("Слива")) {
+                    harvest += cell.getHarvest();
+                    counter++;
+                }
+            }
+        }
+
+        // Avoid division by 0 in case there are no plum trees
+        if (counter > 0) {
+            // Find avg
+            harvest /= counter;
+        }
+
+        return harvest;
+    }
+
     public String[] getColumnNames() {
         return columnNames;
     }

src/MenuActionGetPlumHarvestAvg.java

@@ -0,0 +1,20 @@
+import javax.swing.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
+public class MenuActionGetPlumHarvestAvg implements ActionListener {
+    private DataTableModel  tableModel;
+
+    public MenuActionGetPlumHarvestAvg(DataTableModel tableModel) {
+        this.tableModel = tableModel;
+    }
+
+    public void actionPerformed(ActionEvent e) {
+        System.out.println("Find average plum harvest");
+
+        double plumHarvestAvg = tableModel.getPlumHarvestAvg();
+
+        String text = String.format("Средняя урожайность слив: %.3f", plumHarvestAvg);
+        JOptionPane.showMessageDialog(null, text);
+    }
+}

src/MenuBar.java

@@ -54,7 +54,10 @@ public class MenuBar extends JMenuBar {
         highestHarvestItem.addActionListener(new MenuActionFindHighestHarvest(tableModel));
         menu.add(highestHarvestItem);
 
-        menu.add(createMockMenuItem("Средн Урожай"));
+        JMenuItem plumHarvestAvgItem = new JMenuItem("Средн Урожай");
+        plumHarvestAvgItem.addActionListener(new MenuActionGetPlumHarvestAvg(tableModel));
+        menu.add(plumHarvestAvgItem);
+
         menu.add(createMockMenuItem("Общий урожай"));
         menu.add(createMockMenuItem("Lin Spec"));
         menu.add(createMockMenuItem("Сектор К деревьев"));