From 728fb75bd58b9839055c6cafd9781f2d635f8ec0 Mon Sep 17 00:00:00 2001
From: OF3832 <chengpengyeah@126.com>
Date: Fri, 12 Mar 2021 16:00:49 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=9D=E8=AF=81=E6=8F=92=E5=85=A5=E9=A1=BA?=
 =?UTF-8?q?=E5=BA=8F?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../hcsp/collection/RemoveDuplicateCharsInString.java | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/main/java/com/github/hcsp/collection/RemoveDuplicateCharsInString.java b/src/main/java/com/github/hcsp/collection/RemoveDuplicateCharsInString.java
index cae1919..dd03cda 100644
--- a/src/main/java/com/github/hcsp/collection/RemoveDuplicateCharsInString.java
+++ b/src/main/java/com/github/hcsp/collection/RemoveDuplicateCharsInString.java
@@ -1,6 +1,7 @@
 package com.github.hcsp.collection;
 
-import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 public class RemoveDuplicateCharsInString {
     // 修改这个方法使得它能够输出正确结果：
@@ -8,16 +9,16 @@ public class RemoveDuplicateCharsInString {
     // 输入ccbbaa返回cba
     // 输入apple返回aple
     public static String removeDuplicateCharsInString(String s) {
-        HashSet<Character> charSet = new HashSet<>();
+        Set<Character> charSet = new CopyOnWriteArraySet<>();
         for (int i = 0; i < s.length(); i++) {
             charSet.add(s.charAt(i));
         }
 
-        String result = "";
+        StringBuilder result = new StringBuilder();
         for (Character ch : charSet) {
-            result += ch;
+            result.append(ch);
         }
 
-        return result;
+        return result.toString();
     }
 }