realised class ArrayList

create const: DEFAULT_CAPACITY,
GROW_FACTOR
implements: add() - 3, get(), set(),
remove() - 2, size(), isEmpty()
added the methods grow(), checkIndex()

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

@@ -1,48 +1,123 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    private static final int DEFAULT_CAPACITY = 10;
+    private static final double GROWTH_FACTOR = 1.5;
+    private Object[] values;
+    private int size;
+    private T oldValue;
+
+    public ArrayList() {
+        values = new Object[DEFAULT_CAPACITY];
+    }
+
     @Override
     public void add(T value) {
-
+        grow();
+        values[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bounds " + index);
+        }
 
+        grow();
+
+        if (index == size) {
+            values[size++] = value;
+        } else {
+            System.arraycopy(values, index, values, index + 1, size - index);
+            values[index] = value;
+            size++;
+        }
     }
 
     @Override
     public void addAll(List<T> list) {
+        grow();
 
+        for (int i = 0; i < list.size(); i++) {
+            T element = list.get(i);
+            add(element);
+        }
     }
 
     @Override
     public T get(int index) {
-        return null;
+        checkIndex(index);
+
+        return (T) values[index];
     }
 
     @Override
     public void set(T value, int index) {
+        checkIndex(index);
 
+        oldValue = (T)values[index];
+        values[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkIndex(index);
+
+        oldValue = (T)values[index];
+
+        for (int i = index; i < size - 1; i++) {
+            values[i] = values[i + 1];
+        }
+
+        size--;
+        values[size] = null;
+        return oldValue;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        int index = -1;
+
+        for (int i = 0; i < size; i++) {
+            if ((element == null && values[i] == null)
+                    || (element != null && element.equals(values[i]))) {
+                index = i;
+                break;
+            }
+        }
+
+        if (index == -1) {
+            throw new NoSuchElementException("Element not found " + element);
+        }
+
+        return remove(index);
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return size == 0;
+    }
+
+    private void grow() {
+        if (size == values.length) {
+            int newCapacity = (int)(values.length * GROWTH_FACTOR);
+            Object[] newValues = new Object[newCapacity];
+            System.arraycopy(values, 0, newValues, 0, size);
+            values = newValues;
+        }
+    }
+
+    private void checkIndex(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bounds " + index);
+        }
     }
 }