From e1f2920261a4b22c6967da79cd1de2a8c948236f Mon Sep 17 00:00:00 2001
From: markilue <745518019@qq.com>
Date: Fri, 23 Sep 2022 16:51:54 +0800
Subject: [PATCH] =?UTF-8?q?collection=E7=9A=84=E4=B8=80=E4=BA=9B=E5=9F=BA?=
 =?UTF-8?q?=E7=A1=80=E9=A2=98=E5=AD=A6=E4=B9=A0?=
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Content-Type: text/plain; charset=UTF-8
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---
 .../java_learning/collection/Problem.java     | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 Big_data_example/java_learning/src/main/java/com/markilue/java_learning/collection/Problem.java

diff --git a/Big_data_example/java_learning/src/main/java/com/markilue/java_learning/collection/Problem.java b/Big_data_example/java_learning/src/main/java/com/markilue/java_learning/collection/Problem.java
new file mode 100644
index 0000000..7be3d3e
--- /dev/null
+++ b/Big_data_example/java_learning/src/main/java/com/markilue/java_learning/collection/Problem.java
@@ -0,0 +1,35 @@
+package com.markilue.java_learning.collection;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * @BelongsProject: java_learning
+ * @BelongsPackage: com.markilue.java_learning.collection
+ * @Author: dingjiawen
+ * @CreateTime: 2022-09-23  16:38
+ * @Description:
+ * TODO  面试题中的一些集合类题
+ * @Version: 1.0
+ */
+public class Problem {
+
+
+    @Test
+    public void test(){
+        //注意这里可以不指定泛型不报错，但是不能加上<>了。不然会报错
+        List list1=new ArrayList();
+        list1.add(0);
+        List list2=list1;
+        System.out.println(list1.get(0) instanceof Integer);  //true
+        System.out.println(list2.get(0) instanceof Integer);  //true
+        System.out.println(list1.get(0).getClass());  //class java.lang.Integer
+        System.out.println(list1.get(0).getClass().getName());  //java.lang.Integer
+        Class<?> aClass = list1.get(0).getClass();
+        String name = list1.get(0).getClass().getName();
+    }
+
+
+}