String.intern() 与常量池

DreamCats · DreamCats · commit fa4e3c81cad3 · 2020-02-12T01:43:52.000+08:00
diff --git a/Basics/src/com/strings/SIntern.java b/Basics/src/com/strings/SIntern.java
@@ -0,0 +1,32 @@
+/**
+ * @program JavaBooks
+ * @description: String.Intern
+ * @author: mf
+ * @create: 2020/02/12 01:35
+ */
+
+package com.strings;
+
+/**
+ * 使用 String.intern() 可以保证相同内容的字符串变量引用同一的内存对象。
+ */
+public class SIntern {
+    public static void main(String[] args) {
+        // 采用new String创建对象
+        String s1 = new String("aaa");
+        String s2 = new String("aaa");
+        System.out.println(s1 == s2); // false
+
+        // 将s1的对象通过intern放到String Pool中
+        String s3 = s1.intern();
+        System.out.println(s1.intern() == s3); // true
+        System.out.println(s1.intern() == s2.intern()); // true
+        System.out.println(s3 == "aaa"); // true
+
+
+        // 如果是采用 "bbb" 这种使用双引号的形式创建字符串实例，会自动地将新建的对象放入 String Pool 中。
+        String s4 = "bbb";
+        String s5 = "bbb";
+        System.out.println(s4 == s5); // true
+    }
+}
diff --git a/README.md b/README.md
@@ -35,6 +35,7 @@
     - [说说&和&&的区别](https://github.com/DreamCats/JavaBooks/blob/master/Basics/Java%E9%9D%A2%E8%AF%95%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86.md#%E8%AF%B4%E8%AF%B4%E5%92%8C%E7%9A%84%E5%8C%BA%E5%88%AB)
     - [short s1 = 1; s1 = s1 + 1;有什么错? short s1 = 1; s1 += 1; 有什么错?](https://github.com/DreamCats/JavaBooks/blob/master/Basics/Java%E9%9D%A2%E8%AF%95%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86.md#short-s1--1-s1--s1--1%E6%9C%89%E4%BB%80%E4%B9%88%E9%94%99-short-s1--1-s1--1-%E6%9C%89%E4%BB%80%E4%B9%88%E9%94%99)
     - [char 型变量中能不能存贮一个中文汉字?为什么?](https://github.com/DreamCats/JavaBooks/blob/master/Basics/Java%E9%9D%A2%E8%AF%95%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86.md#char-%E5%9E%8B%E5%8F%98%E9%87%8F%E4%B8%AD%E8%83%BD%E4%B8%8D%E8%83%BD%E5%AD%98%E8%B4%AE%E4%B8%80%E4%B8%AA%E4%B8%AD%E6%96%87%E6%B1%89%E5%AD%97%E4%B8%BA%E4%BB%80%E4%B9%88)
+    - [整形包装缓存池例子vlaueof](/Basics/src/com/pack/IntegerPackDemo.java)
 - **构造器**
     - [构造器 Constructor 是否可被 override?](https://github.com/DreamCats/JavaBooks/blob/master/Basics/Java%E9%9D%A2%E8%AF%95%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86.md#%E6%9E%84%E9%80%A0%E5%99%A8-constructor-%E6%98%AF%E5%90%A6%E5%8F%AF%E8%A2%AB-override)
     - [构造方法有哪些特性？](https://github.com/DreamCats/JavaBooks/blob/master/Basics/Java%E9%9D%A2%E8%AF%95%E5%9F%BA%E7%A1%80%E7%9F%A5%E8%AF%86.md#%E6%9E%84%E9%80%A0%E6%96%B9%E6%B3%95%E6%9C%89%E5%93%AA%E4%BA%9B%E7%89%B9%E6%80%A7)
