Overridden ArrayList methods

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

@@ -1,48 +1,109 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    private static final int DEFAULT_CAPACITY = 10;
+    private int size;
+    private T[] elementData;
+
+    public ArrayList() {
+        this.elementData = (T[]) new Object[DEFAULT_CAPACITY];
+        this.size = 0;
+    }
+
+    public void indexValidator(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index is not valid");
+        }
+    }
+
+    public Object[] grow(T[] elementData, int size) {
+        if ((size + 1) >= elementData.length) {
+            int newCapacity = elementData.length + (elementData.length >> 1);
+            T[] newElementData = (T[]) new Object[newCapacity];
+            System.arraycopy(elementData, 0, newElementData, 0, size);
+            elementData = newElementData;
+        }
+        return elementData;
+    }
+
     @Override
     public void add(T value) {
-
+        elementData = (T[]) grow(elementData, size);
+        elementData[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
-
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException("Index is not valid");
+        }
+        if (size == elementData.length) {
+            elementData = (T[]) grow(elementData, size);
+        }
+        for (int i = size; i > index; i--) {
+            elementData[i] = elementData[i - 1];
+        }
+        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;
+        indexValidator(index);
+        return elementData[index];
     }
 
     @Override
     public void set(T value, int index) {
+        indexValidator(index);
+        elementData[index] = value;
 
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        indexValidator(index);
+        T removedValue = elementData[index];
+        System.arraycopy(elementData, index + 1, elementData, index, size - index - 1);
+        size--;
+        return removedValue;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        if (element == null) {
+            for (int i = 0; i < size; i++) {
+                if (elementData[i] == null) {
+                    return remove(i);
+                }
+            }
+        } else {
+            for (int i = 0; i < size; i++) {
+                if (element.equals(elementData[i])) {
+                    return remove(i);
+                }
+            }
+        }
+        throw new NoSuchElementException("Element not found");
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return size == 0;
     }
 }