Can you check my task, please?

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

@@ -1,48 +1,145 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    private T[] array;
+    private int lastElementIndex;
+    private final int baseSize = 10;
+    private final double enlargingSize = 1.5;
+
+    public ArrayList() {
+        array = (T[])new Object[baseSize];
+        lastElementIndex = -1;
+    }
+
+    public ArrayList(T[] array) {
+        this.array = array;
+        lastElementIndex = array.length - 1;
+    }
+
     @Override
     public void add(T value) {
-
+        if (lastElementIndex < array.length - 1) {
+            ++lastElementIndex;
+            array[lastElementIndex] = value;
+        } else {
+            changeSize(enlargingSize);
+            add(value);
+        }
     }
 
     @Override
     public void add(T value, int index) {
-
+        if (index < 0 || index > lastElementIndex + 1) {
+            throw new ArrayListIndexOutOfBoundsException("Invalid index, can't be added to"
+                    + " non-existing position.");
+        }
+        if (index == 0 && lastElementIndex < 0) {
+            add(value);
+            return;
+        }
+        ++lastElementIndex;
+        if (lastElementIndex == array.length - 1) {
+            changeSize(enlargingSize);
+        }
+        Object[] newArray = new Object[array.length];
+        System.arraycopy(array, 0, newArray, 0, index);
+        newArray[index] = value;
+        System.arraycopy(array, index, newArray, index + 1, array.length - index - 1);
+        array = (T[])newArray;
     }
 
     @Override
     public void addAll(List<T> list) {
-
+        int expectedLength = (list.size() + this.size());
+        if (expectedLength <= array.length) {
+            for (int i = 0; i < list.size(); ++i) {
+                add(list.get(i));
+            }
+        } else {
+            changeSize(enlargingSize);
+            addAll(list);
+        }
     }
 
     @Override
     public T get(int index) {
-        return null;
+        checkIfArgumentIsCorrect(index);
+        return array[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        checkIfArgumentIsCorrect(index);
+        array[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkIfArgumentIsCorrect(index);
+        T temp = array[index];
+        for (int i = index; i < lastElementIndex; ++i) {
+            array[i] = array[i + 1];
+        }
+        lastElementIndex--;
+        return temp;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        int index = -1;
+        for (int i = 0; i <= lastElementIndex; ++i) {
+            if (element == array[i]) {
+                index = i;
+                break;
+            } else if (element != null && element.equals(array[i])) {
+                index = i;
+                break;
+            }
+        }
+        if (index == -1) {
+            throw new NoSuchElementException("You're trying to remove element,"
+                    + " that is not present in the list");
+        }
+        remove(index);
+        return element;
     }
 
     @Override
     public int size() {
-        return 0;
+        return lastElementIndex + 1;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return (lastElementIndex == -1);
+    }
+
+    private T[] changeSize(double coefficient) {
+        int newLength = (int)(array.length * coefficient);
+        Object[] tempArray = new Object[(int) newLength];
+        if (newLength > array.length) {
+            for (int i = 0; i < array.length; i++) {
+                tempArray[i] = array[i];
+            }
+        } else if (newLength < array.length) {
+            for (int i = 0; i < newLength; i++) {
+                tempArray[i] = array[i];
+            }
+        }
+        array = (T[]) tempArray;
+        return array;
+    }
+
+    private void checkIfArgumentIsCorrect(int argument) {
+        if (argument < 0) {
+            throw new ArrayListIndexOutOfBoundsException("You're trying"
+                    + " to access element, index of which is lower than 0");
+        }
+        if (argument > lastElementIndex) {
+            throw new ArrayListIndexOutOfBoundsException("You're trying"
+                    + " to access element, index of which is larger than array length.");
+        }
     }
 }