diff --git a/day05/src/com/inmind/array01/Demo04.java b/day05/src/com/inmind/array01/Demo04.java
new file mode 100644
index 0000000..777758f
--- /dev/null
+++ b/day05/src/com/inmind/array01/Demo04.java
@@ -0,0 +1,19 @@
+package com.inmind.array01;
+/*
+.数组的异常_空指针异常
+NullPointerException
+空指针异常
+ */
+public class Demo04 {
+    public static void main(String[] args) {
+        int[] arr = {1, 2, 3};//省略了new
+        System.out.println(arr[2]);//3
+
+        arr = null;//空常量，它的作用是给引用数据类型初始化的，也就是引用数据类型的默认值
+        if (arr != null) {//对引用数据类型增加安全性的判断
+            System.out.println(arr[2]);//如果对应的引用数据类型为null，还继续操作，就会报NullPointerException
+        }
+
+        System.out.println("程序结束");
+    }
+}