initial commit

src/main/java/core/basesyntax/ArrayList.java

@@ -1,48 +1,124 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    public static final int DEFAULT_CAPACITY = 10;
+    public static final double ARRAY_GROWTH_VALUE = 1.5;
+    private T[] elementData;
+    private int size;
+
+    public ArrayList() {
+        elementData = (T[]) new Object[DEFAULT_CAPACITY];
+    }
+
     @Override
     public void add(T value) {
-
+        growIfArrayIsFull();
+        elementData[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
-
+        checkIndexForAdd(index);
+        growIfArrayIsFull();
+        System.arraycopy(elementData, index, elementData, index + 1,
+                size - index);
+        elementData[index] = value;
+        size++;
     }
 
     @Override
     public void addAll(List<T> list) {
-
+        for (int i = 0; i < list.size(); i++) {
+            add(list.get(i));
+        }
     }
 
     @Override
     public T get(int index) {
-        return null;
+        checkIndexValidation(index);
+        return elementData[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        checkIndexValidation(index);
+        elementData[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkIndexValidation(index);
+        T oldValue = elementData[index];
+        removeByIndex(elementData, index);
+        return oldValue;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int i = 0; i < size; i++) {
+            if (equalsElement(element, elementData[i])) {
+                return remove(i);
+            }
+        }
+        throw new NoSuchElementException("Element '" + element + "' not found");
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
+        return size == 0;
+    }
+
+    private void checkIndexForAdd(int index) {
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException("Can't add value to index " + index
+                    + ". Index is invalid.");
+        }
+    }
+
+    private void growIfArrayIsFull() {
+        if (size == elementData.length) {
+            T[] grownElementData = (T[]) new Object[(int) (elementData.length
+                    * ARRAY_GROWTH_VALUE)];
+            System.arraycopy(elementData, 0, grownElementData, 0, size);
+            elementData = grownElementData;
+        }
+    }
+
+    private void checkIndexValidation(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index is invalid.");
+        }
+    }
+
+    private boolean equalsElement(T element, Object object) {
+        if (element == object) {
+            return true;
+        }
+        if (element == null || object == null) {
+            return false;
+        }
+        if (element.getClass().equals(object.getClass())) {
+            T current = (T) object;
+            return (current == element || (current != null && current.equals(element)));
+        }
         return false;
     }
+
+    private void removeByIndex(Object[] elementData, int index) {
+        if ((size - 1) > index) {
+            System.arraycopy(elementData, index + 1, elementData, index,
+                    size - index - 1);
+        } else {
+            elementData[index] = null;
+        }
+        size--;
+    }
 }