Implemented all needed methods in ArrayList class, used necessary exc…

…eptions for "out of bound" or "no such element" events.

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

@@ -1,48 +1,110 @@
 package core.basesyntax;
 
+import java.util.NoSuchElementException;
+
 public class ArrayList<T> implements List<T> {
+    public static final int DEFAULT_CAPACITY = 10;
+    public static final double RESIZE_FACTOR = 1.5;
+
+    private T[] elements;
+    private int size;
+
+    public ArrayList() {
+        elements = (T[]) new Object[DEFAULT_CAPACITY];
+        size = 0;
+    }
+
+    private void ensureCapacity() {
+        if (size == this.elements.length) {
+            this.resize((int) (elements.length * RESIZE_FACTOR));
+        }
+    }
+
+    private void resize(int newCapacity) {
+        T[] elements = (T[]) new Object[newCapacity];
+        System.arraycopy(this.elements, 0, elements, 0, size);
+        this.elements = elements;
+    }
+
     @Override
     public void add(T value) {
-
+        this.ensureCapacity();
+        this.elements[size] = value;
+        this.size++;
     }
 
     @Override
     public void add(T value, int index) {
-
+        if (index < 0 || index > this.size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bound.");
+        }
+        this.ensureCapacity();
+        T[] swap = (T[]) new Object[size - index];
+        System.arraycopy(this.elements, index, swap, 0, size - index);
+        this.elements[index] = value;
+        System.arraycopy(swap, 0, this.elements, index + 1, size - index);
+        this.size++;
     }
 
     @Override
     public void addAll(List<T> list) {
-
+        for (int i = 0; i < list.size(); i++) {
+            this.add(list.get(i));
+        }
     }
 
     @Override
     public T get(int index) {
-        return null;
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bounds");
+        }
+        return elements[index];
     }
 
     @Override
     public void set(T value, int index) {
-
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bounds");
+        }
+        elements[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException("Index out of bounds");
+        }
+        T swap = elements[index];
+        System.arraycopy(this.elements, index + 1, this.elements, index, size - index - 1);
+        size--;
+        return swap;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int i = 0; i < size; i++) {
+            if (elements[i] == null && element != null) {
+                continue;
+            }
+            if (element == null && elements[i] == null) {
+                this.remove(i);
+                return null;
+            }
+            if (elements[i].equals(element)) {
+                this.remove(i);
+                return element;
+            }
+        }
+        throw new NoSuchElementException("No such element for removing");
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return this.size() == 0;
     }
 }