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int","2026-09-16T09:13:38.582777Z",[266],{"metadata":267,"spec":269,"status":270,"postCount":98},{"name":87,"creationTimestamp":88,"labels":268},{"haloweb.section":90},{"displayName":92,"slug":87,"cover":93,"description":94,"priority":27,"hideFromList":95,"preventParentPostCascadeQuery":95},{"permalink":97,"postCount":98,"visiblePostCount":98},{"metadata":272,"spec":273,"status":277,"categories":278,"content":284},{"name":168,"creationTimestamp":169},{"title":171,"slug":172,"cover":93,"excerpt":274,"publishTime":174,"categories":275,"tags":276,"priority":27,"pinned":95,"deleted":95,"visible":112,"allowComment":108},{"raw":93,"autoGenerate":108},[87],[],{"permalink":178,"excerpt":179,"lastModifyTime":180,"phase":117},[279],{"metadata":280,"spec":282,"status":283,"postCount":98},{"name":87,"creationTimestamp":88,"labels":281},{"haloweb.section":90},{"displayName":92,"slug":87,"cover":93,"description":94,"priority":27,"hideFromList":95,"preventParentPostCascadeQuery":95},{"permalink":97,"postCount":98,"visiblePostCount":98},{"content":285,"raw":285},"\u003Ch2>一、不可变的体现\u003C\u002Fh2>\n\u003Cp>String 内部用 \u003Ccode>final char[]\u003C\u002Fcode>（JDK 9 后是 \u003Ccode>byte[]\u003C\u002Fcode>）存储字符，且没有提供修改内部数组的方法，一旦创建内容就不能改。所谓\"修改\"其实是创建新对象。\u003C\u002Fp>\n\u003Ch2>二、设计原因\u003C\u002Fh2>\n\u003Col>\n\u003Cli>\u003Cstrong>字符串常量池复用\u003C\u002Fstrong>：相同字面量共享同一对象，节省内存。\u003C\u002Fli>\n\u003Cli>\u003Cstrong>线程安全\u003C\u002Fstrong>：不可变对象天然线程安全，多线程下无需同步。\u003C\u002Fli>\n\u003Cli>\u003Cstrong>hashCode 缓存\u003C\u002Fstrong>：String 的 hashCode 在首次计算后缓存，作为 HashMap 键时性能稳定。\u003C\u002Fli>\n\u003Cli>\u003Cstrong>安全性\u003C\u002Fstrong>：作为参数传递时不会被意外篡改，如数据库连接串、文件名。\u003C\u002Fli>\n\u003C\u002Fol>\n\u003Ch2>三、注意事项\u003C\u002Fh2>\n\u003Cpre>\u003Ccode class=\"language-java\">String s = "hello";\ns += " world";   \u002F\u002F 不是修改原对象，而是新建 "hello world"\n\u003C\u002Fcode>\u003C\u002Fpre>\n\u003Cp>频繁拼接字符串会产生大量临时对象，应使用 StringBuilder。\u003C\u002Fp>"]