Solution

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

@@ -1,48 +1,105 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+import java.util.Objects;
+
 public class ArrayList<T> implements List<T> {
+    private static final int ARRAY_START_SIZE = 10;
+    private static final double COEFFICIENT = 1.5;
+    private Object[] list;
+    private int size;
+
+    public ArrayList() {
+        list = new Object[ARRAY_START_SIZE];
+    }
+
     @Override
     public void add(T value) {
-
+        growIfArrayFull();
+        list[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
-
+        if (index > size() || index < 0) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of range");
+        }
+        if (index == size()) {
+            add(value);
+            return;
+        }
+        growIfArrayFull();
+        Object[] newList = new Object[list.length];
+        System.arraycopy(list, 0, newList, 0, index);
+        newList[index] = value;
+        System.arraycopy(list, index, newList, index + 1, size() - index);
+        list = newList;
+        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;
+        checkIndexIsValid(index);
+        return (T) list[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        checkIndexIsValid(index);
+        list[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkIndexIsValid(index);
+        final T oldElement = (T) list[index];
+        System.arraycopy(list, index + 1, list, index, size() - 1 - index);
+        size--;
+        list[size] = null;
+        return oldElement;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int index = 0; index < size; index++) {
+            if (Objects.equals(element, list[index])) {
+                return remove(index);
+            }
+        }
+        throw new NoSuchElementException("No such element " + element);
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return size == 0;
+    }
+
+    private void checkIndexIsValid(int index) {
+        if (index >= size() || index < 0) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of range");
+        }
+    }
+
+    private void growIfArrayFull() {
+        if (list.length <= size) {
+            int newSize = (int) (list.length * COEFFICIENT);
+            Object[] temp = new Object[newSize];
+            System.arraycopy(list, 0, temp, 0, size);
+            list = temp;
+        }
     }
 }