Need help with btSpellCheck. I get error message on if (!dictionary.contains(key)) {

 

package application;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.stream.Collectors;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class SpellCheckFrequentWordsFX extends Application {

Dictionary dictionary = new Dictionary();
ArrayList document = new ArrayList<>();


Map wordFrequency = new TreeMap<>();
Map map = new TreeMap<>();

public void start(Stage primaryStage) throws IOException, SQLException {

 TextArea textArea = new TextArea();
 textArea.setWrapText(true);

 Label nameLabel = new Label("File to Load: ");
 ChoiceBox textfileToCheck = new ChoiceBox();
 textfileToCheck.getItems().addAll("Sample.txt", "BillOfRights.txt", "greatgatsby.txt", "warandpeace.txt");
 textfileToCheck.getSelectionModel().select(0);
 String message = (LoadTheTextFile(textfileToCheck.getValue()));
 textfileToCheck.setOnAction(event -> {
  try {
   textArea.setText(LoadTheTextFile(textfileToCheck.getValue()));
  } catch (SQLException e) {
   e.printStackTrace();
  }
 });

 Button btFrequentWords = new Button("Frequent Words");
 Button btSpellCheck = new Button("Spell Check");

 Button btClearAnswers = new Button("Clear");
 Button btnExit = new Button("Exit");

 HBox hBoxTop = new HBox(nameLabel, textfileToCheck, btFrequentWords, btSpellCheck, btClearAnswers, btnExit);
 hBoxTop.setSpacing(10);
 hBoxTop.setAlignment(Pos.CENTER);
 hBoxTop.setPadding(new Insets(5, 5, 5, 5));

 BorderPane borderPane = new BorderPane();
 borderPane.setTop(hBoxTop);
 borderPane.setCenter(textArea);

 dictionary = DbConnection.ReadDictionary();
 // Dictionary Requires a Size Method
 // textArea.setText("Dictionary Loaded with " + dictionary.size() + " words");
 textArea.appendText(message + "");

 btFrequentWords.setOnAction(new EventHandler() {
  public void handle(ActionEvent e) {
   String output = "";    
   wordFrequency.clear();
   
   int maxCount = 0;
   
   wordFrequency = document.stream().map(String :: toLowerCase).filter(word -> !word.trim().isEmpty()).collect(Collectors.toMap(word -> word, word -> 1, (a,b) -> a + b, TreeMap::new));
   
   for (String word : document) {
    Integer cnt = wordFrequency.get(word);
    if (cnt != null) {
     if ( cnt > maxCount) {
      maxCount = cnt;
     }
    }
   }
   
   for (String k : wordFrequency.keySet()) {
    if (maxCount == wordFrequency.get(k)) {
     output += "Words that appear "  + maxCount + " times: " + k + "";
    }
   }
   textArea.setText(output);
  }
 });
 btSpellCheck.setOnAction(new EventHandler() {
  public void handle(ActionEvent e) {
   String output = "";
   map.clear();
   boolean missSpelled = false;
   int missSpelledCount = 0;
   
   for (String key : document) {
                   if (key.length() > 0) {
                           key = key.toLowerCase();
                           if (!dictionary.contains(key)) {
                            missSpelled = true;
                            missSpelledCount++;
                           }
                           if (!map.containsKey(key)) {
                                   if (missSpelled) {
                                           map.put(key, 0);
                                   } else {
                                           map.put(key, 1);
                                   }
                           } else {
                                   int value = map.get(key);
                                   value++;
                                   map.put(key, value);
                           }
                   }
                   missSpelled = false;
           }
   List > entries = new ArrayList<>(map.entrySet());
   Collections.sort(entries, (entry1, entry2) -> {
    return entry2.getValue().compareTo(entry1.getValue());
   });
   
   int maxValue = 0;
   for (Map.Entry entry : entries) {
    if (entry.getValue() > maxValue) {
     maxValue = entry.getValue();
    }
   }
   
   output += "---------- Most Frequent Words ----------";
   for (Map.Entry entry : entries) {
    if (entry.getValue() == maxValue) {
     output += entry.getKey() + " ";
    }
   }
   
   output += "";
   
   output += "---------- Frequency of Word ----------";
   int lastValue = 0;
   StringBuilder stringBuilder = new StringBuilder ();
   
   for (Map.Entry entry : entries) {
    if(!(entry.getValue() == lastValue)) {
     output += stringBuilder;
     stringBuilder.setLength(0);
     stringBuilder.append("frequency " + entry.getValue() + "" + " ");
    }
    if (entry.getValue() == lastValue) {
     stringBuilder = stringBuilder.append(", " + entry.getValue());
    } else {
     stringBuilder = stringBuilder.append(entry.getKey());
    }
    lastValue = entry.getValue();
   }
   
   output += "---------- Misspelled Words ---------- Count: " + missSpelledCount + "";
   stringBuilder.setLength(0);
   
   boolean beganPrintingMissSpelled = false;
   for (Map.Entry entry : entries) {
    if (beganPrintingMissSpelled == false) {
     stringBuilder = stringBuilder.append(entry.getKey());
    } else {
     stringBuilder = stringBuilder.append(", " + entry.getKey());
    }
    beganPrintingMissSpelled = true;
   }
   output += stringBuilder;
   textArea.setText(output);
  }
 });

 btClearAnswers.setOnAction(e -> {
  textArea.setText("");
 });

 btnExit.setOnAction(e -> {
  System.exit(0);
 });

 // Create a scene and place it in the stage
 Scene scene = new Scene(borderPane, 800, 450);
 scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
 primaryStage.setTitle("Spell Checking with Frequent Words");
 primaryStage.setScene(scene);
 primaryStage.show();
}

private String LoadTheTextFile(String fileName) throws SQLException {
 document.clear();
 File f = new File(fileName);
 Scanner scan;
 try {
  scan = new Scanner(f);
  while (scan.hasNext()) {
   String l = scan.next();
   if (l.endsWith(",") || l.endsWith(".") || l.endsWith("!") || l.endsWith("?") || l.endsWith(":")) {
    l = l.substring(0, l.length() - 1);
   }
   l = (l.replaceAll("[^a-zA-Z]", " ")).trim();
   String[] result = l.split(" ");
   for (int i = 0; i < result.length; i++) {
    if (result[i].length() > 0)
     document.add(result[i]);
   }
  }
  scan.close();
 } catch (FileNotFoundException e1) {
  e1.printStackTrace();
 }
 StringBuilder sb = new StringBuilder();
 for (String s : document)
  sb = sb.append(s + " ");
 return fileName + " loaded with " + document.size() + " words" + sb;
}

/**
 * The main method is only needed for the IDE with limited JavaFX support. Not
 * needed for running from the command line.
 */
public static void main(String[] args) {
 launch(args);
}
}