diff --git a/day07/src/com/inmind/arraylist03/Student.java b/day07/src/com/inmind/arraylist03/Student.java
new file mode 100644
index 0000000..98c2da7
--- /dev/null
+++ b/day07/src/com/inmind/arraylist03/Student.java
@@ -0,0 +1,20 @@
+package com.inmind.arraylist03;
+
+public class Student {
+    String name;
+    int age;
+    String gender;
+
+    public Student() {
+    }
+
+    public Student(String name, int age, String gender) {
+        this.name = name;
+        this.age = age;
+        this.gender = gender;
+    }
+
+    public void showSelf(){
+        System.out.println("当前学生叫"+this.name+",年龄"+this.age+"岁，性别为"+this.gender);
+    }
+}
diff --git a/day07/src/com/inmind/arraylist03/Test12.java b/day07/src/com/inmind/arraylist03/Test12.java
new file mode 100644
index 0000000..aa7a1c3
--- /dev/null
+++ b/day07/src/com/inmind/arraylist03/Test12.java
@@ -0,0 +1,36 @@
+package com.inmind.arraylist03;
+
+import java.util.ArrayList;
+
+/*
+常用类-ArrayList-练习2_添加对象
+创建一个ArrayList集合，存放3个Student对象，再把他们的学号，姓名，性别输出
+ */
+public class Test12 {
+    public static void main(String[] args) {
+        //1.创建存放学生的集合
+        ArrayList<Student> list = new ArrayList<>();
+        //2.先创建学生对象，再放入集合
+        /*Student s1 = new Student("张三1",19,"男");
+        Student s2 = new Student("张三2",18,"女");
+        Student s3 = new Student("张三3",20,"男");
+        list.add(s1);
+        list.add(s2);
+        list.add(s3);*/
+        list.add(new Student("张三1",19,"男"));
+        list.add(new Student("张三2",18,"女"));
+        list.add(new Student("张三3",20,"男"));
+        System.out.println(list.size());//3个学生
+        //方式一：集合的遍历，把每个对象的属性打印出来
+        for (int i = 0; i < list.size(); i++) {
+            Student s = list.get(i);
+            System.out.println("当前学生叫"+s.name+",年龄"+s.age+"岁，性别为"+s.gender);
+        }
+        System.out.println("-----------------");
+        //方式二：直接在Student类中定义展示方法，集合的遍历，调用各个学生对象的展示方法
+        for (int i = 0; i < list.size(); i++) {
+            Student s = list.get(i);
+            s.showSelf();
+        }
+    }
+}
diff --git a/day07/src/com/inmind/arraylist03/Test13.java b/day07/src/com/inmind/arraylist03/Test13.java
new file mode 100644
index 0000000..5bee810
--- /dev/null
+++ b/day07/src/com/inmind/arraylist03/Test13.java
@@ -0,0 +1,36 @@
+package com.inmind.arraylist03;
+
+import java.util.ArrayList;
+
+//常用类-ArrayList-练习3_指定格式拼接字符串
+public class Test13 {
+    public static void main(String[] args) {
+        ArrayList<String> list = new ArrayList<String>();
+        list.add("张三");
+        list.add("李四");
+        list.add("王五");
+        list.add("王五");
+        list.add("王五");
+        list.add("王五");
+        list.add("王五");
+        printList(list);
+    }
+
+    //定义以指定格式打印集合的方法(ArrayList类型作为参数)，使用@分隔每个元素。格式参照 [元素1@元素2@元素3]。
+    public static void printList(ArrayList<String> arrayList) {
+        String result = "[";
+        //对集合进行遍历
+        for (int i = 0; i < arrayList.size(); i++) {
+            //获取集合中的元素
+            String element = arrayList.get(i);
+            //如果是最后一个元素（size-1）：那就拼接]而不是@
+            if (i == (arrayList.size() - 1)) {
+//                result = result + element + "]";
+                result  += element + "]";
+            } else {
+                result += element + "@";
+            }
+        }
+        System.out.println(result);
+    }
+}