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diff --git a/src/main/java/io/github/ehlxr/test/TestString.java b/src/main/java/io/github/ehlxr/test/TestString.java
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+/*
+ * The MIT License (MIT)
+ *
+ * Copyright © 2021 xrv <xrg@live.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package io.github.ehlxr.test;
+
+/**
+ * @author ehlxr
+ * @since 2021-05-14 16:17.
+ */
+public class TestString {
+    public static void main(String[] args) {
+        String s1 = "abc";
+        String s2 = "ab";
+        String s3 = s2 + "c";
+        System.out.println(s1 == s3);//false
+
+        String s4 = s3.intern();
+        System.out.println(s1 == s3);//false
+        System.out.println(s1 == s4);//true
+
+        String s5 = "abc";
+        System.out.println(s1 == s5);//true
+
+        String s6 = new String("abc");
+        String s7 = new String("abc");
+        System.out.println(s6 == s7);//false
+
+    }
+}