From c0e0686fb21f0824980e27bb5ed65ded5ae18592 Mon Sep 17 00:00:00 2001
From: Yevhenii Liashenko <paradoxrial@gmail.com>
Date: Fri, 27 Oct 2023 18:19:35 +0300
Subject: [PATCH] implement `ArrayList`

---
 src/main/java/core/basesyntax/ArrayList.java | 79 +++++++++++++++++---
 1 file changed, 70 insertions(+), 9 deletions(-)

diff --git a/src/main/java/core/basesyntax/ArrayList.java b/src/main/java/core/basesyntax/ArrayList.java
index 8d6477943..000b66fb9 100644
--- a/src/main/java/core/basesyntax/ArrayList.java
+++ b/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 Object[] elementData;
+    private int size;
+
+    public ArrayList() {
+        elementData = new Object[DEFAULT_CAPACITY];
+    }
+
     @Override
     public void add(T value) {
-
+        if (size == elementData.length) {
+            grow();
+        }
+        elementData[size] = value;
+        size++;
     }
 
     @Override
     public void add(T value, int index) {
-
+        if (index < 0 || index > size) {
+            throw new ArrayListIndexOutOfBoundsException(
+                    "Index " + index + " out of bounds for length" + elementData.length);
+        }
+        if (size == elementData.length) {
+            grow();
+        }
+        System.arraycopy(elementData, index, elementData, index + 1, size - index);
+        elementData[index] = value;
+        size++;
     }
 
     @Override
     public void addAll(List<T> list) {
-
+        while (size + list.size() >= elementData.length) {
+            grow();
+        }
+        for (int i = 0; i < list.size(); i++) {
+            elementData[size + i] = list.get(i);
+        }
+        size += list.size();
     }
 
     @Override
     public T get(int index) {
-        return null;
+        checkToCorrectIndex(index);
+        return elementData(index);
     }
 
     @Override
     public void set(T value, int index) {
-
+        checkToCorrectIndex(index);
+        elementData[index] = value;
     }
 
     @Override
     public T remove(int index) {
-        return null;
+        checkToCorrectIndex(index);
+        final T removedElement = elementData(index);
+        System.arraycopy(elementData, index + 1, elementData, index, size - 1 - index);
+        elementData[size - 1] = null;
+        size--;
+        return removedElement;
     }
 
     @Override
     public T remove(T element) {
-        return null;
+        for (int i = 0; i < size; i++) {
+            if (elementData[i] == element
+                    || elementData[i] != null && elementData[i].equals(element)) {
+                remove(i);
+                return element;
+            }
+        }
+        throw new NoSuchElementException("ArrayList don't have such element");
     }
 
     @Override
     public int size() {
-        return 0;
+        return size;
     }
 
     @Override
     public boolean isEmpty() {
-        return false;
+        return size == 0;
+    }
+
+    private T elementData(int index) {
+        return (T) elementData[index];
+    }
+
+    private void checkToCorrectIndex(int index) {
+        if (index < 0 || index >= size) {
+            throw new ArrayListIndexOutOfBoundsException(
+                    "Index " + index + " out of bounds for length" + elementData.length);
+        }
+    }
+
+    private void grow() {
+        int newCapacity = (int)(elementData.length * 1.5f);
+        Object[] newElementData = new Object[newCapacity];
+        System.arraycopy(elementData, 0, newElementData, 0, elementData.length);
+        elementData = newElementData;
     }
 }