编程语言的异同及选择

Question

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Answer 1

许多语言在设计时就已考虑到了复杂性的问题。但从另一角度看，实际设计时肯定会有另一些问题浮现出来，需把它们考虑到这个复杂性的问题里。不可避免地，其他那些问题最后会变成最让程序员头痛的。例如，C++必须同C保持向后兼容（使C程序员能尽快地适应新环境），同时又要保证编程的效率。C++在这两个方面都设计得很好，为其赢得了不少的声誉。但它们同时也暴露出了额外的复杂性，阻碍了某些项目的成功实现（当然，你可以责备程序员和管理层，但假如一种语言能通过捕获你的错误而提供帮助，它为什么不那样做呢？）。作为另一个例子，Visual Basic（VB）同当初的BASIC有关的紧密的联系。而BASIC并没有打算设计成一种能全面解决问题的语言，所以堆加到VB身上的所有扩展都造成了令人头痛和难于管理和维护的语法。另一方面，C++、VB和其他如Smalltalk之类的语言均在复杂性的问题上下了一番功夫。由此得到的结果便是，它们在解决特定类型的问题时是非常成功的。
在理解到Java最终的目标是减轻程序员的负担时，我才真正感受到了震憾，尽管它的潜台词好象是说：“除了缩短时间和减小产生健壮代码的难度以外，我们不关心其他任何事情。”在目前这个初级阶段，达到那个目标的后果便是代码不能特别快地运行（尽管有许多保证都说Java终究有一天会运行得多么快），但它确实将开发时间缩短到令人惊讶的地步——几乎只有创建一个等效C++程序一半甚至更短的时间。这段节省下来的时间可以产生更大的效益，但Java并不仅止于此。它甚至更上一层楼，将重要性越来越明显的一切复杂任务都封装在内，比如网络程序和多线程处理等等。Java的各种语言特性和库在任何时候都能使那些任务轻而易举完成。而且最后，它解决了一些真正有些难度的复杂问题：跨平台程序、动态代码改换以及安全保护等等。换在从前，其中任何每一个都能使你头大如斗。所以不管我们见到了什么性能问题，Java的保证仍然是非常有效的：它使程序员显著提高了程序设计的效率！

Answer 2

请教 zhang1976(被大风刮的到处跑)：
麻烦请非常简单介绍一下，你们做什么样的项目或产品的时候，换到Java后比原来的哪种语言效率提高了多少？
多谢！