Resolves checkstyle errors for intercepting-filter, interpreter, iterator (#1065)

* Reduces checkstyle errors in intercepting-filter

* Reduces checkstyle errors in interpreter

* Reduces checkstyle errors in iterator

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/AbstractFilter.java

@@ -25,13 +25,13 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * Base class for order processing filters. Handles chain management.
- *
  */
 public abstract class AbstractFilter implements Filter {
 
   private Filter next;
 
-  public AbstractFilter() {}
+  public AbstractFilter() {
+  }
 
   public AbstractFilter(Filter next) {
     this.next = next;

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/AddressFilter.java

@@ -26,9 +26,8 @@ package com.iluwatar.intercepting.filter;
 /**
  * Concrete implementation of filter This filter is responsible for checking/filtering the input in
  * the address field.
- * 
- * @author joshzambales
  *
+ * @author joshzambales
  */
 public class AddressFilter extends AbstractFilter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/App.java

@@ -24,7 +24,6 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * 
  * When a request enters a Web application, it often must pass several entrance tests prior to the
  * main processing stage. For example, - Has the client been authenticated? - Does the client have a
  * valid session? - Is the client's IP address from a trusted network? - Does the request path
@@ -32,28 +31,26 @@ package com.iluwatar.intercepting.filter;
  * the browser type of the client? Some of these checks are tests, resulting in a yes or no answer
  * that determines whether processing will continue. Other checks manipulate the incoming data
  * stream into a form suitable for processing.
- * <p>
- * The classic solution consists of a series of conditional checks, with any failed check aborting
- * the request. Nested if/else statements are a standard strategy, but this solution leads to code
- * fragility and a copy-and-paste style of programming, because the flow of the filtering and the
- * action of the filters is compiled into the application.
- * <p>
- * The key to solving this problem in a flexible and unobtrusive manner is to have a simple
+ *
+ * <p>The classic solution consists of a series of conditional checks, with any failed check
+ * aborting the request. Nested if/else statements are a standard strategy, but this solution leads
+ * to code fragility and a copy-and-paste style of programming, because the flow of the filtering
+ * and the action of the filters is compiled into the application.
+ *
+ * <p>The key to solving this problem in a flexible and unobtrusive manner is to have a simple
  * mechanism for adding and removing processing components, in which each component completes a
  * specific filtering action. This is the Intercepting Filter pattern in action.
- * <p>
- * In this example we check whether the order request is valid through pre-processing done via
- * {@link Filter}. Each field has its own corresponding {@link Filter}
- * <p>
- * 
- * @author joshzambales
  *
+ * <p>In this example we check whether the order request is valid through pre-processing done via
+ * {@link Filter}. Each field has its own corresponding {@link Filter}.
+ *
+ * @author joshzambales
  */
 public class App {
 
   /**
-   * Program entry point
-   * 
+   * Program entry point.
+   *
    * @param args command line args
    */
   public static void main(String[] args) {

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Client.java

@@ -23,6 +23,9 @@
 
 package com.iluwatar.intercepting.filter;
 
+import java.awt.BorderLayout;
+import java.awt.GridLayout;
+
 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JLabel;
@@ -32,18 +35,15 @@ import javax.swing.JTextArea;
 import javax.swing.JTextField;
 import javax.swing.SwingUtilities;
 import javax.swing.WindowConstants;
-import java.awt.BorderLayout;
-import java.awt.GridLayout;
 
 /**
- * The Client class is responsible for handling the input and running them through filters inside the
- * {@link FilterManager}.
+ * The Client class is responsible for handling the input and running them through filters inside
+ * the {@link FilterManager}.
+ *
+ * <p>This is where {@link Filter}s come to play as the client pre-processes the request before
+ * being displayed in the {@link Target}.
  *
- * This is where {@link Filter}s come to play as the client pre-processes the request before being displayed in the
- * {@link Target}.
- * 
  * @author joshzambales
- *
  */
 public class Client extends JFrame { // NOSONAR
 
@@ -57,7 +57,7 @@ public class Client extends JFrame { // NOSONAR
   private JButton processButton;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public Client() {
     super("Client System");
@@ -107,8 +107,10 @@ public class Client extends JFrame { // NOSONAR
     });
 
     processButton.addActionListener(e -> {
-      Order order = new Order(jtFields[0].getText(), jtFields[1].getText(), jtAreas[0].getText(), jtFields[2].getText(),
-          jtAreas[1].getText());
+      Order order =
+          new Order(jtFields[0].getText(), jtFields[1].getText(), jtAreas[0].getText(), jtFields[2]
+              .getText(),
+              jtAreas[1].getText());
       jl.setText(sendRequest(order));
     });
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/ContactFilter.java

@@ -26,10 +26,9 @@ package com.iluwatar.intercepting.filter;
 /**
  * Concrete implementation of filter This filter checks for the contact field in which it checks if
  * the input consist of numbers and it also checks if the input follows the length constraint (11
- * digits)
- * 
- * @author joshzambales
+ * digits).
  *
+ * @author joshzambales
  */
 public class ContactFilter extends AbstractFilter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/DepositFilter.java

@@ -24,10 +24,9 @@
 package com.iluwatar.intercepting.filter;
 
 /**
- * Concrete implementation of filter This checks for the deposit code
- * 
- * @author joshzambales
+ * Concrete implementation of filter This checks for the deposit code.
  *
+ * @author joshzambales
  */
 public class DepositFilter extends AbstractFilter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Filter.java

@@ -26,9 +26,8 @@ package com.iluwatar.intercepting.filter;
 /**
  * Filters perform certain tasks prior or after execution of request by request handler. In this
  * case, before the request is handled by the target, the request undergoes through each Filter
- * 
- * @author joshzambales
  *
+ * @author joshzambales
  */
 public interface Filter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/FilterChain.java

@@ -26,7 +26,7 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * Filter Chain carries multiple filters and help to execute them in defined order on target.
- * 
+ *
  * @author joshzambales
  */
 public class FilterChain {
@@ -35,7 +35,7 @@ public class FilterChain {
 
 
   /**
-   * Adds filter
+   * Adds filter.
    */
   public void addFilter(Filter filter) {
     if (chain == null) {
@@ -46,7 +46,7 @@ public class FilterChain {
   }
 
   /**
-   * Execute filter chain
+   * Execute filter chain.
    */
   public String execute(Order order) {
     if (chain != null) {

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/FilterManager.java

@@ -25,9 +25,8 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * Filter Manager manages the filters and {@link FilterChain}.
- * 
- * @author joshzambales
  *
+ * @author joshzambales
  */
 public class FilterManager {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/NameFilter.java

@@ -26,9 +26,8 @@ package com.iluwatar.intercepting.filter;
 /**
  * Concrete implementation of filter. This filter checks if the input in the Name field is valid.
  * (alphanumeric)
- * 
- * @author joshzambales
  *
+ * @author joshzambales
  */
 public class NameFilter extends AbstractFilter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Order.java

@@ -25,7 +25,6 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * Order class carries the order data.
- *
  */
 public class Order {
 
@@ -35,12 +34,16 @@ public class Order {
   private String depositNumber;
   private String orderItem;
 
-  public Order() {}
+  public Order() {
+  }
 
   /**
-   * Constructor
+   * Constructor.
    */
-  public Order(String name, String contactNumber, String address, String depositNumber, String order) {
+  public Order(
+      String name, String contactNumber, String address,
+      String depositNumber, String order
+  ) {
     this.name = name;
     this.contactNumber = contactNumber;
     this.address = address;

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/OrderFilter.java

@@ -25,9 +25,8 @@ package com.iluwatar.intercepting.filter;
 
 /**
  * Concrete implementation of filter. This checks for the order field.
- * 
- * @author joshzambales
  *
+ * @author joshzambales
  */
 public class OrderFilter extends AbstractFilter {
 

intercepting-filter/src/main/java/com/iluwatar/intercepting/filter/Target.java

@@ -23,6 +23,11 @@
 
 package com.iluwatar.intercepting.filter;
 
+import java.awt.BorderLayout;
+import java.awt.Dimension;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JPanel;
@@ -32,16 +37,11 @@ import javax.swing.JTable;
 import javax.swing.SwingUtilities;
 import javax.swing.WindowConstants;
 import javax.swing.table.DefaultTableModel;
-import java.awt.BorderLayout;
-import java.awt.Dimension;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 
 /**
  * This is where the requests are displayed after being validated by filters.
- * 
- * @author mjoshzambales
  *
+ * @author mjoshzambales
  */
 public class Target extends JFrame { //NOSONAR
 
@@ -52,14 +52,14 @@ public class Target extends JFrame { //NOSONAR
   private JButton del;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public Target() {
     super("Order System");
     setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
     setSize(640, 480);
     dtm =
-        new DefaultTableModel(new Object[] {"Name", "Contact Number", "Address", "Deposit Number",
+        new DefaultTableModel(new Object[]{"Name", "Contact Number", "Address", "Deposit Number",
             "Order"}, 0);
     jt = new JTable(dtm);
     del = new JButton("Delete");
@@ -85,7 +85,7 @@ public class Target extends JFrame { //NOSONAR
   }
 
   public void execute(String[] request) {
-    dtm.addRow(new Object[] {request[0], request[1], request[2], request[3], request[4]});
+    dtm.addRow(new Object[]{request[0], request[1], request[2], request[3], request[4]});
   }
 
   class DListener implements ActionListener {

interpreter/src/main/java/com/iluwatar/interpreter/App.java

@@ -23,35 +23,30 @@
 
 package com.iluwatar.interpreter;
 
+import java.util.Stack;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.Stack;
-
 /**
- * 
  * The Interpreter pattern is a design pattern that specifies how to evaluate sentences in a
  * language. The basic idea is to have a class for each symbol (terminal or nonterminal) in a
  * specialized computer language. The syntax tree of a sentence in the language is an instance of
  * the composite pattern and is used to evaluate (interpret) the sentence for a client.
- * <p>
- * In this example we use the Interpreter pattern to break sentences into expressions (
- * {@link Expression}) that can be evaluated and as a whole form the result.
- * 
+ *
+ * <p>In this example we use the Interpreter pattern to break sentences into expressions ({@link
+ * Expression}) that can be evaluated and as a whole form the result.
  */
 public class App {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
 
   /**
-   * 
    * Program entry point.
-   * <p>
-   * Expressions can be evaluated using prefix, infix or postfix notations This sample uses postfix,
-   * where operator comes after the operands
-   * 
+   *
+   * <p>Expressions can be evaluated using prefix, infix or postfix notations This sample uses
+   * postfix, where operator comes after the operands.
+   *
    * @param args command line args
-   * 
    */
   public static void main(String[] args) {
     String tokenString = "4 3 2 - 1 + *";
@@ -84,7 +79,7 @@ public class App {
   }
 
   /**
-   * Get expression for string
+   * Get expression for string.
    */
   public static Expression getOperatorInstance(String s, Expression left, Expression right) {
     switch (s) {

interpreter/src/main/java/com/iluwatar/interpreter/Expression.java

@@ -24,9 +24,7 @@
 package com.iluwatar.interpreter;
 
 /**
- * 
- * Expression
- *
+ * Expression.
  */
 public abstract class Expression {
 

interpreter/src/main/java/com/iluwatar/interpreter/MinusExpression.java

@@ -24,9 +24,7 @@
 package com.iluwatar.interpreter;
 
 /**
- * 
- * MinusExpression
- *
+ * MinusExpression.
  */
 public class MinusExpression extends Expression {
 

interpreter/src/main/java/com/iluwatar/interpreter/MultiplyExpression.java

@@ -24,9 +24,7 @@
 package com.iluwatar.interpreter;
 
 /**
- * 
- * MultiplyExpression
- *
+ * MultiplyExpression.
  */
 public class MultiplyExpression extends Expression {
 

interpreter/src/main/java/com/iluwatar/interpreter/NumberExpression.java

@@ -24,9 +24,7 @@
 package com.iluwatar.interpreter;
 
 /**
- * 
- * NumberExpression
- *
+ * NumberExpression.
  */
 public class NumberExpression extends Expression {
 

interpreter/src/main/java/com/iluwatar/interpreter/PlusExpression.java

@@ -24,9 +24,7 @@
 package com.iluwatar.interpreter;
 
 /**
- * 
- * PlusExpression
- *
+ * PlusExpression.
  */
 public class PlusExpression extends Expression {
 

iterator/src/main/java/com/iluwatar/iterator/App.java

@@ -39,8 +39,8 @@ import org.slf4j.LoggerFactory;
 /**
  * The Iterator pattern is a design pattern in which an iterator is used to traverse a container and
  * access the container's elements. The Iterator pattern decouples algorithms from containers.
- * <p>
- * In this example the Iterator ({@link Iterator}) adds abstraction layer on top of a collection
+ *
+ * <p>In this example the Iterator ({@link Iterator}) adds abstraction layer on top of a collection
  * ({@link TreasureChest}). This way the collection can change its internal implementation without
  * affecting its clients.
  */
@@ -85,7 +85,7 @@ public class App {
   }
 
   /**
-   * Program entry point
+   * Program entry point.
    *
    * @param args command line args
    */

iterator/src/main/java/com/iluwatar/iterator/Iterator.java

@@ -24,7 +24,8 @@
 package com.iluwatar.iterator;
 
 /**
- * Iterator interface to be implemented by iterators over various data structures
+ * Iterator interface to be implemented by iterators over various data structures.
+ *
  * @param <T> generically typed for various objects
  */
 public interface Iterator<T> {

iterator/src/main/java/com/iluwatar/iterator/bst/BstIterator.java

@@ -32,7 +32,7 @@ import java.util.NoSuchElementException;
  * expect to retrieve TreeNodes according to the Integer's natural ordering (1, 2, 3...)
  *
  * @param <T> This Iterator has been implemented with generic typing to allow for TreeNodes of
- *     different value types
+ *            different value types
  */
 public class BstIterator<T extends Comparable<T>> implements Iterator<TreeNode<T>> {
 
@@ -46,7 +46,7 @@ public class BstIterator<T extends Comparable<T>> implements Iterator<TreeNode<T
   /**
    * This BstIterator manages to use O(h) extra space, where h is the height of the tree It achieves
    * this by maintaining a stack of the nodes to handle (pushing all left nodes first), before
-   * handling self or right node
+   * handling self or right node.
    *
    * @param node TreeNode that acts as root of the subtree we're interested in.
    */
@@ -58,6 +58,8 @@ public class BstIterator<T extends Comparable<T>> implements Iterator<TreeNode<T
   }
 
   /**
+   * Checks if there exists next element.
+   *
    * @return true if this iterator has a "next" element
    */
   @Override
@@ -66,6 +68,8 @@ public class BstIterator<T extends Comparable<T>> implements Iterator<TreeNode<T
   }
 
   /**
+   * Gets the next element.
+   *
    * @return TreeNode next. The next element according to our in-order traversal of the given BST
    * @throws NoSuchElementException if this iterator does not have a next element
    */

iterator/src/main/java/com/iluwatar/iterator/bst/TreeNode.java

@@ -36,7 +36,7 @@ public class TreeNode<T extends Comparable<T>> {
   private TreeNode<T> right;
 
   /**
-   * Creates a TreeNode with a given value, and null children
+   * Creates a TreeNode with a given value, and null children.
    *
    * @param val The value of the given node
    */
@@ -67,7 +67,7 @@ public class TreeNode<T extends Comparable<T>> {
   }
 
   /**
-   * Inserts new TreeNode based on a given value into the subtree represented by self
+   * Inserts new TreeNode based on a given value into the subtree represented by self.
    *
    * @param valToInsert The value to insert as a new TreeNode
    */

iterator/src/main/java/com/iluwatar/iterator/list/Item.java

@@ -24,9 +24,7 @@
 package com.iluwatar.iterator.list;
 
 /**
- * 
- * Item
- *
+ * Item.
  */
 public class Item {
 

iterator/src/main/java/com/iluwatar/iterator/list/ItemType.java

@@ -24,9 +24,7 @@
 package com.iluwatar.iterator.list;
 
 /**
- * 
- * ItemType enumeration
- *
+ * ItemType enumeration.
  */
 public enum ItemType {
 

iterator/src/main/java/com/iluwatar/iterator/list/TreasureChest.java

@@ -28,29 +28,27 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- *
  * TreasureChest, the collection class.
- *
  */
 public class TreasureChest {
 
   private List<Item> items;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public TreasureChest() {
     items = List.of(
-            new Item(ItemType.POTION, "Potion of courage"),
-            new Item(ItemType.RING, "Ring of shadows"),
-            new Item(ItemType.POTION, "Potion of wisdom"),
-            new Item(ItemType.POTION, "Potion of blood"),
-            new Item(ItemType.WEAPON, "Sword of silver +1"),
-            new Item(ItemType.POTION, "Potion of rust"),
-            new Item(ItemType.POTION, "Potion of healing"),
-            new Item(ItemType.RING, "Ring of armor"),
-            new Item(ItemType.WEAPON, "Steel halberd"),
-            new Item(ItemType.WEAPON, "Dagger of poison"));
+        new Item(ItemType.POTION, "Potion of courage"),
+        new Item(ItemType.RING, "Ring of shadows"),
+        new Item(ItemType.POTION, "Potion of wisdom"),
+        new Item(ItemType.POTION, "Potion of blood"),
+        new Item(ItemType.WEAPON, "Sword of silver +1"),
+        new Item(ItemType.POTION, "Potion of rust"),
+        new Item(ItemType.POTION, "Potion of healing"),
+        new Item(ItemType.RING, "Ring of armor"),
+        new Item(ItemType.WEAPON, "Steel halberd"),
+        new Item(ItemType.WEAPON, "Dagger of poison"));
   }
 
   public Iterator<Item> iterator(ItemType itemType) {
@@ -58,7 +56,7 @@ public class TreasureChest {
   }
 
   /**
-   * Get all items
+   * Get all items.
    */
   public List<Item> getItems() {
     return new ArrayList<>(items);

iterator/src/main/java/com/iluwatar/iterator/list/TreasureChestItemIterator.java

@@ -27,9 +27,7 @@ import com.iluwatar.iterator.Iterator;
 import java.util.List;
 
 /**
- *
- * TreasureChestItemIterator
- *
+ * TreasureChestItemIterator.
  */
 public class TreasureChestItemIterator implements Iterator<Item> {
 
@@ -38,7 +36,7 @@ public class TreasureChestItemIterator implements Iterator<Item> {
   private ItemType type;
 
   /**
-   * Constructor
+   * Constructor.
    */
   public TreasureChestItemIterator(TreasureChest chest, ItemType type) {
     this.chest = chest;