diff --git a/day08/src/com/inmind/string01/Demo07.java b/day08/src/com/inmind/string01/Demo07.java
new file mode 100644
index 0000000..39ae158
--- /dev/null
+++ b/day08/src/com/inmind/string01/Demo07.java
@@ -0,0 +1,36 @@
+package com.inmind.string01;
+/*
+5.常用类-String-的转换方法
+
+public char[] toCharArray () ：将此字符串转换为新的字符数组。
+public byte[] getBytes () ：使用平台的默认字符集将该 String编码转换为新的字节数组。
+public String replace (CharSequence target, CharSequence replacement) ：将与target匹配的字符串使用replacement字符串替换。
+ */
+public class Demo07 {
+    public static void demo1() {
+        //public char[] toCharArray () ：将此字符串转换为新的字符数组。
+        String str = "abc";
+        char[] chars = str.toCharArray();
+        for (int i = 0; i < chars.length; i++) {
+            System.out.println(chars[i]);
+        }
+    }
+
+    public static void demo2() {
+        //public byte[] getBytes () ：使用平台的默认字符集将该 String编码转换为新的字节数组
+        String str = "abc";
+        byte[] bytes = str.getBytes();
+        for (int i = 0; i < bytes.length; i++) {
+            System.out.println(bytes[i]);
+        }
+    }
+
+    public static void main(String[] args) {
+        //public String replace (CharSequence target, CharSequence replacement) ：将与target匹配的字符串使用replacement字符串替换。
+        String str = "今天，天气很好，我很高兴";
+        //想把str中所有的天，都替换为*
+        String newStr = str.replace("天", "***");
+        System.out.println(str);
+        System.out.println(newStr);
+    }
+}
diff --git a/day08/src/com/inmind/string01/Demo08.java b/day08/src/com/inmind/string01/Demo08.java
new file mode 100644
index 0000000..35d0656
--- /dev/null
+++ b/day08/src/com/inmind/string01/Demo08.java
@@ -0,0 +1,15 @@
+package com.inmind.string01;
+/*
+public String[] split(String regex) ：将此字符串按照给定的regex（规则）拆分为字符串数组。
+ */
+public class Demo08 {
+    public static void main(String[] args) {
+        String str = "hello,world,day,day,up";
+        //注意：按,切割，按什么分割，该字符串就不会出现
+        String[] strings = str.split(",");
+        System.out.println(strings);
+        for (int i = 0; i < strings.length; i++) {
+            System.out.println(strings[i]);
+        }
+    }
+}
diff --git a/day08/src/com/inmind/string01/Test09.java b/day08/src/com/inmind/string01/Test09.java
new file mode 100644
index 0000000..aa48fdf
--- /dev/null
+++ b/day08/src/com/inmind/string01/Test09.java
@@ -0,0 +1,16 @@
+package com.inmind.string01;
+
+public class Test09 {
+    public static void main(String[] args) {
+        //将字符串转为自定义类对象（Student）
+        String str1 = "1,张三,18";
+        String str2 = "2,李四,20";
+
+        String[] arr1 = str1.split(",");
+        Student s1 = new Student(arr1[1], Integer.parseInt(arr1[2]), Integer.parseInt(arr1[0]));
+        System.out.println(s1.getId());
+        System.out.println(s1.getName());
+        System.out.println(s1.getAge());
+
+    }
+}