Merge pull request TheAlgorithms#1396 from rbshealy/master

StepfenShawn · web-flow · commit ab88fed35665 · 2020-08-13T10:43:36.000+08:00
Add javadoc comments and Cleanup DynamicArray.java
diff --git a/DataStructures/DynamicArray/DynamicArray.java b/DataStructures/DynamicArray/DynamicArray.java
@@ -1,93 +1,138 @@
 package DataStructures.DynamicArray;
 
-import java.util.Arrays;
-import java.util.ConcurrentModificationException;
-import java.util.Iterator;
-import java.util.NoSuchElementException;
-import java.util.Objects;
-import java.util.function.Consumer;
-import java.util.stream.Stream;
-import java.util.stream.StreamSupport;
+import java.util.*;
 
+/**
+ * This class implements a dynamic array
+ * @param <E> the type that each index of the array will hold
+ */
 public class DynamicArray<E> implements Iterable<E> {
 
-    private int capacity = 10;
-
-    private int size = 0;
-
+    private int capacity;
+    private int size;
     private Object[] elements;
 
+    /**
+     * constructor
+     * @param capacity the starting length of the desired array
+     */
     public DynamicArray(final int capacity) {
+    	this.size = 0;
         this.capacity = capacity;
         this.elements = new Object[this.capacity];
     }
 
+    /**
+     * No-args constructor
+     */
     public DynamicArray() {
+    	this.size = 0;
+    	this.capacity = 10;
         this.elements = new Object[this.capacity];
     }
 
+    /**
+     * Doubles the capacity of the array
+     * @return int the new capacity of the array
+     */
     public int newCapacity() {
-        this.capacity <<= 1;
-
+        this.capacity *= 2; 
+        //changed from this.capacity <<= 1; now much easier to understand
         return this.capacity;
     }
 
+    /**
+     * Adds an element to the array
+     * If full, creates a copy array twice the size of the current one
+     * @param element the element of type <E> to be added to the array
+     */
     public void add(final E element) {
-        if (this.size == this.elements.length)
-            this.elements = Arrays.copyOf(this.elements, newCapacity());
+        if (this.size == this.elements.length) {
+        	this.elements = Arrays.copyOf(this.elements, newCapacity());
+        }
 
         this.elements[this.size] = element;
         size++;
     }
-
+    
+    /**
+     * Places element of type <E> at the desired index
+     * @param index the index for the element to be placed
+     * @param element the element to be inserted
+     */
     public void put(final int index, E element) {
-//        Objects.checkIndex(index, this.size);
-
         this.elements[index] = element;
     }
 
+    /**
+     * get method for element at a given index
+     * returns null if the index is empty
+     * @param index the desired index of the element
+     * @return <E> the element at the specified index
+     */
     public E get(final int index) {
         return getElement(index);
     }
-
+    
+    /**
+     * Removes an element from the array
+     * @param index the index of the element to be removed
+     * @return <E> the element removed
+     */
     public E remove(final int index) {
         final E oldElement = getElement(index);
         fastRemove(this.elements, index);
 
         return oldElement;
     }
-
-    public int size() {
+    
+    /**
+     * get method for size field
+     * @return int size
+     */
+    public int getSize() {
         return this.size;
     }
 
+    /**
+     * isEmpty helper method
+     * @return boolean true if the array contains no elements, false otherwise
+     */
     public boolean isEmpty() {
         return this.size == 0;
     }
-
+    
     public Stream<E> stream() {
         return StreamSupport.stream(spliterator(), false);
     }
 
     private void fastRemove(final Object[] elements, final int index) {
         final int newSize = this.size - 1;
 
-        if (newSize > index)
-            System.arraycopy(elements, index + 1, elements, index, newSize - index);
+        if (newSize > index) {
+        	System.arraycopy(elements, index + 1, elements, index, newSize - index);
+        }
 
         elements[this.size = newSize] = null;
     }
 
     private E getElement(final int index) {
-//        Objects.checkIndex(index, this.size);
         return (E) this.elements[index];
     }
 
+    /**
+     * returns a String representation of this object
+     * @return String a String representing the array
+     */
     @Override
     public String toString() {
         return Arrays.toString(Arrays.stream(this.elements).filter(Objects::nonNull).toArray());
     }
 
+    /**
+     * Creates and returns a new Dynamic Array Iterator
+     * @return Iterator a Dynamic Array Iterator
+     */
     @Override
     public Iterator iterator() {
         return new DynamicArrayIterator();
@@ -109,7 +154,6 @@ public E next() {
             if (this.cursor > DynamicArray.this.elements.length) throw new ConcurrentModificationException();
 
             final E element = DynamicArray.this.getElement(this.cursor);
-
             this.cursor++;
 
             return element;
@@ -120,7 +164,6 @@ public void remove() {
             if (this.cursor < 0) throw new IllegalStateException();
 
             DynamicArray.this.remove(this.cursor);
-
             this.cursor--;
         }
 
@@ -134,6 +177,10 @@ public void forEachRemaining(Consumer<? super E> action) {
         }
     }
 
+    /**
+     * This class is the driver for the DynamicArray<E> class
+     * it tests a variety of methods and prints the output
+     */
     public static void main(String[] args) {
         DynamicArray<String> names = new DynamicArray<>();
         names.add("Peubes");
@@ -147,7 +194,7 @@ public static void main(String[] args) {
 
         System.out.println(names);
 
-        System.out.println(names.size());
+        System.out.println(names.getSize());
 
         names.remove(0);
 
