From be01ea5048ba009669dbd151befdb78cd8ba800e Mon Sep 17 00:00:00 2001
From: Gilbertat <shiyue45457@gmail.com>
Date: Fri, 12 Oct 2018 18:51:46 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E5=8A=A8=E6=80=81=E6=95=B0?=
 =?UTF-8?q?=E7=BB=84?=
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---
 "java/05_array/\bGenericArray.java" | 164 ++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 "java/05_array/\bGenericArray.java"

diff --git "a/java/05_array/\bGenericArray.java" "b/java/05_array/\bGenericArray.java"
new file mode 100644
index 0000000..4769e72
--- /dev/null
+++ "b/java/05_array/\bGenericArray.java"
@@ -0,0 +1,164 @@
+/**
+ * 
+ * 1）泛型动态数组
+ *
+ * Author: shi
+ */
+
+ public class GenericArray<T> {
+     private T[] data;
+     private int size;
+
+     // 根据传入容量，构造Array
+     public GenericArray(int capacity) {
+         data = (T[]) new Object[capacity];
+         size = 0;
+     }
+
+     // 无参构造方法，默认数组容量为10
+     public GenericArray() {
+         this(10);
+     }
+
+     // 获取数组容量
+     public int getCapacity() {
+         return data.length;
+     }
+
+     // 获取当前元素个数
+     public int count() {
+         return size;
+     }
+
+     // 判断数组是否为空
+     public boolean isEmpty() {
+         return size == 0;
+     }
+
+     // 修改 index 位置的元素
+     public void set(int index, T e) {
+         checkIndex(index);
+         data[index] = e;
+     }
+
+     // 获取对应 index 位置的元素
+     public T get(int index) {
+         checkIndex(index);
+         return data[index];
+     }
+
+     // 查看数组是否包含元素e
+     public boolean contains(T e) {
+         for (int i = 0; i < size; i++) {
+             if (data[i].equals(e)) {
+                 return true;
+             }
+         }
+         return false;
+     }
+
+     // 获取对应元素的下标, 未找到，返回 -1 
+     public int find(T e) {
+         for ( int i = 0; i < size; i++) {
+             if (data[i].equals(e)) {
+                 return i;
+             }
+         }
+         return -1;
+     }
+     
+
+     // 在 index 位置，插入元素e, 时间复杂度 O(m+n)
+     public void add(int index, T e) {
+         checkIndex(index);
+         // 如果当前元素个数等于数组容量，则将数组扩容为原来的2倍
+         if (size == data.length) {
+             resize(2 * data.length);
+         }
+
+         for (int i = size - 1; i >= index; i--) {
+             data[i + 1] = data[i];
+         }
+         data[index] = e;
+         size++;
+     }
+
+     // 向数组头插入元素
+     public void addFirst(T e) {
+         add(0, e);
+     }
+
+     // 向数组尾插入元素
+     public void addLast(T e) {
+         add(size, e);
+     }
+
+     // 删除 index 位置的元素，并返回
+     public T remove(int index) {
+         checkIndex(index);
+         
+         T ret = data[index];
+         for (int i = index + 1; i < size; i++) {
+             data[i - 1] = data[i];
+         }
+         size --;
+         data[size] = null;
+
+         // 缩容
+         if (size == data.length / 4 && data.length / 2 != 0) {
+             resize(data.length / 2);
+         }
+
+         return ret;
+     }
+
+     // 删除第一个元素
+     public T removeFirst() {
+         return remove(0);
+     }
+
+     // 删除末尾元素
+     public T removeLast() {
+         return remove(size - 1);
+     }
+
+     // 从数组中删除指定元素
+     public void removeElement(T e) {
+         int index = find(e);
+         if (index != -1) {
+             remove(index);
+         }
+     }
+
+     @Override
+     public String toString() {
+         StringBuilder builder = new StringBuilder();
+         builder.append(String.format("Array size = %d, capacity = %d \n", size, data.length));
+         builder.append('[');
+         for (int i = 0; i < size; i++) {
+             builder.append(data[i]);
+             if (i != size - 1) {
+                 builder.append(", ");
+             }
+         }
+         builder.append(']');
+         return builder.toString();
+     }
+
+
+     // 扩容方法，时间复杂度 O(n)
+     private void resize(int capacity) {
+         T[] newData = (T[]) new Object[capacity];
+
+         for (int i = 0; i < size; i++) {
+             newData[i] = data[i];
+         }
+         data = newData;
+     }
+
+     private void checkIndex(int index) {
+        if (index < 0 || index > size) {
+            throw new IllegalArgumentException("Add failed! Require index >=0 and index <= size.");
+        }
+     }
+ }