diff --git a/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo5.java b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo5.java
new file mode 100644
index 00000000..cde12f7c
--- /dev/null
+++ b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo5.java
@@ -0,0 +1,20 @@
+/**
+ * @author ykl
+ * @since 2022
+ * @version 1.0
+ */
+public class Demo5 {
+    /**
+     *
+     * @param args canshu
+     * @return 123
+     */
+    public static void main(String[] args) {
+        int i = 128;
+        byte b = (byte)i;//-128 强制类型转换，避免内存溢出。
+        System.out.println(b);
+
+//        操作比较大的数的时候，注意溢出问题。数字之间可以使用下划线进行分割，只起到标识作用。
+
+    }
+}
diff --git a/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo6.java b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo6.java
new file mode 100644
index 00000000..a87da864
--- /dev/null
+++ b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/Demo6.java
@@ -0,0 +1,2 @@
+package com.ykl;public class Demo6 {
+}
diff --git a/Java源代码/Lesson02/BasicLanguage/src/com/ykl/ScannerTest.java b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/ScannerTest.java
new file mode 100644
index 00000000..06007afe
--- /dev/null
+++ b/Java源代码/Lesson02/BasicLanguage/src/com/ykl/ScannerTest.java
@@ -0,0 +1,2 @@
+package com.ykl.com.ykl;public class ScannerTest {
+}