1.JDK 和 JRE 有什么区别？ JDK：Java Development Kit 的简称，Java 开发工具包，提供了 Java 的开发环境和运行环境。 JRE：Java Runtime Environment 的简称，Java 运行环境，为 Java 的运行提供了所需环境。

Note that this will prevent you from returning stringBuilder or assigning it to an out parameter. The normal use case is to concatenate strings in a hot path where the goal is to put as minimal ...