在Linux环境下，使用Java开发应用程序时，可能会遇到与字体相关的错误，特别是在使用像EasyExcel这样的库进行Excel导出时。标题和描述指出的问题是由于Java运行环境（JRE）缺少必要的字体库，导致在处理某些特定字体时抛出空指针异常（NullPointerException）。这个问题在使用OpenJDK时尤其常见，因为OpenJDK默认并不包含完整的字体集。 EasyExcel是一款由阿里开源的轻量级Java库，用于读写Excel文件。它提供了简单易用的API，但在处理涉及特殊字体的Excel模板时，如果系统中没有相应的字体，就可能出现错误。这种情况下，最常见的错误就是`NullPointerException`，这通常是因为EasyExcel试图加载不存在的字体导致的。 OpenJDK是Java Development Kit的一个开源实现，它遵循Java Community Process的规范，但与Oracle JDK相比，可能会有些功能缺失，比如字体库。OpenJDK不包含所有Windows或Mac上常见的字体，因此在处理需要特定字体的场景时，可能会出现问题。 为了解决这个问题，你可以按照以下步骤操作： 1. **下载字体库**：你需要找到缺少的字体库。可以去官方网站或者第三方资源站点下载你需要的字体文件，通常是`.ttf`或`.otf`格式。 2. **复制到JRE目录**：将下载的字体库文件复制到Java运行环境的字体目录。在Linux系统中，这个路径通常是`/usr/lib/jvm/java-版本-openjdk/jre/lib/fonts`。如果你使用的是自定义安装路径的JDK，那么路径可能是`/your/custom/path/to/jre/lib/fonts`。 3. **更新字体缓存**：在Linux系统中，为了使新添加的字体生效，需要更新系统的字体缓存。可以使用`fc-cache`命令，如`sudo fc-cache -fv`。 4. **重启应用**：完成上述步骤后，确保关闭并重新启动使用EasyExcel的应用程序，这样新的字体设置才能被程序识别。 通过这些步骤，你应该能够解决在Linux环境下，使用OpenJDK运行包含特定字体需求的Java应用时遇到的“NullPointerException”问题。不过，为了避免类似问题，你还可以考虑在Excel模板中使用系统广泛支持的通用字体，或者在代码中添加字体替换逻辑，以减少对特定字体的依赖。

软件介绍: 红烛电子教鞭E-Pointer能在电脑屏幕上任何写画，用于教学演示，产品展示。其体积小功能多，是教师教学的得力助手。在屏幕上的操作可保存为JPG或BMP格式图片，软件启动后，按下热键F9即可显示操作界面。使用说明：1.按 F9 键隐藏电子教鞭，再敲显示，并抓取更新的屏幕。2.在组合框上单击鼠标右键可以自由选择画笔宽度，任意一种颜色。3.在屏幕上单击鼠标右键可以撤消上次操作。4.选择矩形，按住 Shift 键可以画出圆角矩形。5.打开 Caps Lock 键可以画出反色内容。

Pointers On C brings the power of pointers to your C programs. Designed for professionals and advanced students, Pointers on C provides a comprehensive resource for those needing in-depth coverage of the C programming language. An extensive explanation of pointer basics and a thorough exploration of their advanced features allows programmers to incorporate the power of pointers into their C programs. Complete coverage, detailed explanations of C programming idioms, and thorough discussion of advanced topics makes Pointers on C a valuable tutorial and reference for students and professionals alike. Features and Benefits Provides complete background information needed for a thorough understanding of C. Covers pointers thoroughly, including syntax, techniques for their effective use and common programming idioms in which they appear. Compares different methods for implementing common abstract data structures. Offers an easy, conversant writing style to clearly explain difficult topics, and contains numerous illustrations and diagrams to help visualize complex concepts. Includes Programming Tips, discussing efficiency, portability, and software engineering issues, and warns of common pitfalls using Caution! Sections. Describes every function on the standard C library. For those who need an up-to-date ANSI overview of the C programming language, this book would be an excellent introduction. Pointers are usually a stumbling block for those programming C initially, but the author does an excellent job of detailing the use of pointers in this book. The use of pointers dominates the entire book, and after studying it, readers will have a thorough, practical knowledge of how to take advantage of the performance power of C language, due mostly to its use of pointers. For those programming in a commercial/business environment, where coding practices are strictly enforced, this book would be a good desk reference, as the author includes discussion of sound programming practices throughout the book. The book would also serve well those involved in teaching C in the classroom, as it contains many exercises, ranging from very easy to highly advanced. And for those readers frequently facing legacy code in C, such as scientific programmers, the author cites the differences between the older "Kernighan-Ritchie" C, and the more modern ANSI C, the latter being used in the book. These differences are indicated in the margin of the book, and are of an enormous help for those who must take older code and get it to run on more up-to-date compilers. The author also endeavors to organize the C code for those who are going on to study C++ and the accompanying object-oriented approach to programming. In addition, he emphasizes how to write C code so as to make it more portable. For those writing commercial applications in C that must be used on different platforms, this is a very important issue of course. Particularly well-written is the author's discussion on the storage class of a variable, noting, for those such as I who are pre-disposed to using recursion, that the formal parameters to a function cannot be static if recursion is to be supported. The book is full of examples such as this that give readers insight on the workings of C that fit their particular programming style. He does discuss `goto' statements in relation to function scope and in C statement structures, but, thankfully, recommends such statements never be used. He gives an interesting counterexample to those who say that goto statements must be used to break out of nested loops. Also, the author discusses the difference between L- and R-values, and this is not usually included in beginning books on C. Dynamic memory allocation has been at times a somewhat painful aspect of programming in C, but the author shows how to do straightforwardly in the book. Having a book like this that is predominantly about pointers is quite a blessing for those who are inexperienced with them or for more experienced programmers who are still uncomfortable with their use. It is not uncommon these days to have to write programs in one's professional work that involve triple pointers or even quadruple pointers. In addition, for embedded systems programming, the use of pointer arithmetic is almost mandatory. This also is true for writing applications in cryptography using C. The author does pay careful attention to pointer arithmetic in the book. The performance pay-off for using pointers is undeniable, and so a thorough knowledge of their use and pit-falls is of upmost importance for those C programmers who are involved in writing performance-sensitive applications. The author discusses in detail what can happen when pointers are misused and gives many examples of what to avoid and good hints for the proper use of pointers. He recommends against the use of the `null' pointer in array searching, and recommends a strategy for circumventing them. Some very helpful diagrams are given for explaining pointer expressions. In addition, the author gives helpful hints on when to use pointers and not subscripts when manipulating arrays in C. The performance issues involved in this are extremely important in scientific programming using C. The author gives a very interesting example of the differences in performance using pointers involving a program to copy the contents of one array into another. Arrays of pointers, useful in data mining applications, are also given ample treatment in this book, and the author addresses the issue of when to use a matrix instead of an array of pointers. The author also gives an effective presentation of functions in C, particularly the construction of recursive functions, and he employs some useful diagrams to illustrate how the variables in a recursive function call change on the stack. The performance hit experienced by using recursion versus iterative loops is discussed in a standard way via the Fibonacci series. Those readers raised in the functional programming paradigm will want to pay notice these performance issues when using C to do recursion. Along the same lines, the author shows how to implement functions with variable argument lists in C. This is another topic that is frequently passed over in beginning books on C. The author's treatment of data structures in C is also very nicely done, and he includes again a topic not usually treated in beginning books on C, namely the concept of a self-referential data structure. These are very important in applications in artificial intelligence, and the author shows how to implement them in C using a data structure that points to itself. This leads to a discussion of incomplete declarations. Very helpful diagrams are used again to discuss how to access members of data structures and how to point to data structures. Bit fields, so often used in embedded system applications, are also given a detailed treatment.

如果你用的是W9.0以下的版本或Tajima(各版本)，在关闭打版软件后出现了上面的消息框，如果你的软件在操作系统升级前没有这个现象的话，可以肯定你在用XP-SP2,这是因为XP-SP2增强了内存管理和安全管理,所以会在使用完田岛或威尔克姆软件在关闭软件后会弹出MEM-BAD-POINTER 报错

如果你用的是W9.0以下的版本或Tajima(各版本)，在关闭打版软件后出现了上面的消息框，如果你的软件在操作系统升级前没有这个现象的话，可以肯定你在用XP-SP2,这是因为XP-SP2增强了内存管理和安全管理,所以会在使用完田岛或威尔克姆软件在关闭软件后会弹出MEM-BAD-POINTER 报错

Peter Alfke所写的文章，里面详细分析介绍了异步FIFO的设计，英语原版资料

c#物理转虚拟地址，在mobile中可直接读取物理地址的内容。

Pointers On C by K.A. Reek. A great book for learning C language

深入介绍C指针的一本好书，你值得拥有，英文版，很清晰，但是不带标签

QSharedPointer Demo示例， 基于VS2019+ Qt5.15