Question

以下是java.util.ArrayList的摘录：

/**
 * Constructs an IndexOutOfBoundsException detail message.
 * Of the many possible refactorings of the error handling code,
 * this "outlining" performs best with both server and client VMs.
 */
private String outOfBoundsMsg(int index) {
    return "Index: "+index+", Size: "+size;
}

以下是com.google.collect.Preconditions的摘录：

  /*
   * All recent hotspots (as of 2009) *really* like to have the natural code
   *
   * if (guardExpression) {
   *    throw new BadException(messageExpression);
   * }
   *
   * refactored so that messageExpression is moved to a separate
   * String-returning method.
   *
   * if (guardExpression) {
   *    throw new BadException(badMsg(...));
   * }
   *
   * The alternative natural refactorings into void or Exception-returning
   * methods are much slower.  This is a big deal - we're talking factors of
   * 2-8 in microbenchmarks, not just 10-20%.  (This is a hotspot optimizer
   * bug, which should be fixed, but that's a separate, big project).
   *
   * The coding pattern above is heavily used in java.util, e.g. in ArrayList.
   * There is a RangeCheckMicroBenchmark in the JDK that was used to test this.

可能会有人透露：

为何需要私人outOfBoundsMsg
“此概述表现最佳......”的意思
我应该开始重构我的代码以包含我的异常构造函数的字符串返回方法吗？

Answer 1

“这个概述表现得最好......”的意思

它与内联相反，但不是标准术语，这就是它被吓唬的原因。

为什么需要私人outOfBoundsMsg

这就是“概述”是指将代码提取到单独的方法。

我应该开始重构我的代码以包含我的异常构造函数的字符串返回方法吗？

如果你关心每次抛出一个没有字符串文字的异常而浪费3纳秒，那么是的。换句话说：NO。

为什么java.util.ArrayList中有私有方法outOfBoundsMsg？

1 个答案: