complete task

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

@@ -1,48 +1,114 @@
 package core.basesyntax;
 
 public class ArrayList<T> implements List<T> {
+    private static final int DEFAULT_CAPACITY = 10;
+    private static final int GROWTH_DIVISOR = 2;
+    private Object[] elementData;
+    private int size;
+
+    public ArrayList() {
+        this.elementData = new Object[DEFAULT_CAPACITY];
+    }
+
     @Override
     public void add(T value) {
-
+        growIfArrayFull();
+        elementData[size++] = value;
     }
 
     @Override
     public void add(T value, int index) {
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException(
+                    "Index: " + index + ", Size: " + size
+            );
+        }
+
+        growIfArrayFull();
 
+        int elementsToMove = size - index;
+        if (elementsToMove > 0) {
+            System.arraycopy(elementData, index, elementData, index + 1, elementsToMove);
+        }
+
+        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;
+        checkIndex(index);
+        return (T) elementData[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        checkIndex(index);
+        elementData[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkIndex(index);
+
+        T value = (T) elementData[index];
+
+        int elementsToMove = size - index - 1;
+        if (elementsToMove > 0) {
+            System.arraycopy(elementData, index + 1, elementData, index, elementsToMove);
+        }
+
+        elementData[--size] = null;
+
+        return value;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int i = 0; i < size; i++) {
+            if ((element == null && elementData[i] == null)
+                    || (element != null && element.equals(elementData[i]))) {
+
+                return remove(i);
+            }
+        }
+
+        throw new java.util.NoSuchElementException(
+                "Element not found: " + element
+        );
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return size == 0;
+    }
+
+    private void growIfArrayFull() {
+        if (size == elementData.length) {
+            int newCapacity = elementData.length + elementData.length / GROWTH_DIVISOR;
+            Object[] newArray = new Object[newCapacity];
+            System.arraycopy(elementData, 0, newArray, 0, size);
+            elementData = newArray;
+        }
+    }
+
+    private void checkIndex(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException(
+                    "Index: " + index + ", Size: " + size
+            );
+        }
     }
 }