diff --git a/BadArray.java b/BadArray.java
new file mode 100644
index 0000000..6a0dada
--- /dev/null
+++ b/BadArray.java
@@ -0,0 +1,14 @@
+public class BadArray {
+    private static int[] store = new int[4];
+
+    public static void putData(int pos, int num) {
+        if (pos < 0) {
+            return;
+        }
+        store[pos] = num;
+    }
+
+    public static void main(String[] args) {
+        putData(5, 100);
+    }
+}
\ No newline at end of file