Practical Makefiles, by example. Practical Makefiles, by example. Rationale. The purpose of this document is to explain how to write practical makefiles for. I want to illustrate, how easy it is to use. IDEs, or makefile generators such as autotools or cmake. The purpose of this document is certainly not, to teach you how to write. You can. certainly arrive to that by extending a simple makefile, and Ill give you a few. Easy Arduino bluetooth example using the Android Phone to connect and toggle an LED. In this tutorial, we will show you how to read a file from a resources folder, in both Java and Unit Test environment. In simple, put files in a resources folder, and. I will not focus on complexity. Finally, its worth spelling out up front that when I say make, Im really. Download Css Editor here. GNU implementation of make, which is packed with useful. It might be. interesting to write a follow up article, providing similar examples for other. BSD make, Watcom make, Borland make, or. Microsofts nmake. But Ill leave that for another time. Converting_Fig4.png?resize=588%2C343&ssl=1' alt='Simple .Obj File Example' title='Simple .Obj File Example' />graphics. Simple object oriented graphics library The library is designed to make it. Put this file somewhere where. As a simple example. Import 2D data DXF, DWG, EPS, AI, SKP, SVG etc. Data can be imported from a huge range of other design programs using a variety of industry standard file formats. Building CC programs. First lets consider an example C program, and how to build it without make. In order to escape the trap of an oversimplified toy program, lets assume. Our game is made up of the following. AIrenderer. h renderer. D mesh data structures loading. Also, our game depends on a number of 3rd party libraries Open. GLLow level graphics library. GLUTCross platform Open. GL window setup event handlinglibpng. PNG image file format readerdecoderzlib. Needed by libpng for lz. To build this program we would first have to run the compiler on each. Simple .Obj File Example' title='Simple .Obj File Example' />Then, we would have to feed all the object files to the linker possibly. C compiler front end for convenience, instructing it to link. GL lglut lpng lz lm. Obviously, such tediousness could be automated with a shell script. However, that would be a grossly sub optimal solution, as it would recompile. Enter make. Make is a much more elegant solution to our building problems. We create a file. Makefile, which contains a set of rules describing build products. Then when we. ask make to build our program binary, it recursively traverses the dependency. Warning do not run away terrified by the first makefile example. Its only. meant to illustrate how make works, so its needlessly verbose. If youre easily. A makefile for 9. Back to our game example, the binary mygame, obviously depends on. So, lets define two make rules for creating these two. GL lglut lpng lz lm. Essentially for each rule, the part before the colon is the filename we want to. And finally, in. subsequent lines, we just type the commands needed to make this happen. Note that each line in the commands part of a rule needs to begin with a leading. Spaces will not work, it really has to be a tab character, so pay extra. So, if we modify main. In order to build it, make will have to use the declared dependency files, so it. To build main. o, make sees that it needs main. Similarly, returning to the initial rule, since now main. Simpler makefile. Obviously, having to type rules for each of our source files is tedious, and. Make actually knows how to create object code from C. So here is a slightly simpler makefile for. GL lglut lpng lz lm. Similarly. although not useful for this particular rule, there is also the lt variable. We substitute the value of any variable built in. However, one peculiarity of. If we want to use longer names, we have to parenthesize the name before. So for instance if we had. If we instead tried to use obj then make. A makefile for 9. Theres one last thing bugging me in the last example. I hate having to type. Thankfully it. turns out we dont need to do that either. See the following example srcwildcard. LDFLAGS l. GL lglut lpng lz lm. CC o LDFLAGS. PHONY cleanclean. The first line of this example collects all source files in the current. Then, the second line transforms the contents. I also used a new variable called LDFLAGS for the list of libraries. LDFLAGS is conventionally used for this usage. CFLAGS and CXXFLAGS can be used to pass flags to the C. C compilers respectively. Finally, I added a new rule for cleaning up every target, in order to rebuild. The clean rule is marked as phony, because. In order to run any rule. So, for instance, to clean everything in this. Further improvements. The makefile listed above is sufficient for most small programs youll ever. In this section, Ill go over a few improvements for larger projects. Multiple source directories. Lets say you have some source files under src, other source files under. Also, to make it. C and C in any of. Heres a very simple modification which handles this. LDFLAGS l. GL lglut lpng lz lm. CXX o LDFLAGSThe rest is exactly the same as previously. Note that I used the CXX. C programs, automatically linking libstdc. Also, backslashes at the end of lines serve to merge multiple lines. Handling cross platform differences. So far, in all the examples, Ive linked Open. GL and GLUT by passing the l. GL lglut flags to the linker. Thats how reasonable UNIX systems do it, but what. UNIX like abominations like Mac. OSX. where you have to use the following command line arguments framework Open. GL. framework GLUT since Open. GL and GLUT they are frameworks and not just. Simple use uname s to figure out if were. Mac. OSX, and modify the LDFLAGS variable accordingly LDFLAGSlibgl lpng lz lm. Open. GL framework GLUT. GL lglut. The order of defining libgl and defining LDFLAGS doesnt matter, as long. LDFLAGS wont be evaluated and thus require substitution of the libgl. A slightly more elegant, but not exactly equivalent way of doing the above would. LDFLAGSlibglshell uname s lpng lz lm. Linux l. GL lglut. Darwin framework Open. GL framework GLUT. I said not exactly equivalent, because in this way we would have to enumerate. UNIX systems wed like to support instead of just handling them in. Wildcard rules. As I mentioned above, make knows how to compile C and C source files to create. CCCFLAGS o c lt. But lets say you want to compile code for a new language, which make knows. There is a mechanism to write generic rules, so that you wont. If you wish to inform make, on the generic form of rules for building object. FOOFLAGS o c lt. Then, whenever make needs to build xyzzy. Automatic include dependency tracking. The built in rule for compiling C source files, is similar to. CCCFLAGS o c lt. Which means, that if we change foo. There are, however, usually many more dependencies. Specifically, if foo. For simple hacks with a couple of source and header files, we can afford to just. Make cant possibly know what constitutes a dependency, and include a syntactic. However with the help of our compilers pre processor, we. Well write a wildcard rule to generate makefile fragments with an explicit rule. Then well instruct make to include these makefile fragments in. Any missing makefile fragments will be. Finally. well add a rule to clean all these dependency files the makefile fragments. LDFLAGS l. GL lglut lpng lz lm. CC o LDFLAGS. CPPCFLAGS lt MM MT. PHONY cleanclean. PHONY cleandepcleandep. The added lines are marked with comments in the example above. To see exactly. what the C preprocessor outputs when instructed to write dependency information. MM MT foo. o. Thats right, it just outputs a single makefile rule Which is exactly what we. Building sub projects. Consider the following case our game has source files in src, but we also. How would we integrate that in our build systemVery simply, instruct make to first build libfoo, by running make after. JSON. simple example Read and write JSONBy mkyong August 1. Updated January 1. Viewed 1,3. 55,8. JSON. simple is a simple Java library for JSON processing, read and write JSON data and full compliance with JSON specification RFC4. In this tutorial, we show you how to use JSON. JSON data from to a file. JSON. simple Dependency. JSON. simple is available at Maven central repository. Id com. googlecode. Id. lt artifact. Id json simplelt artifact. Id. lt version 1. Write JSON to file. In below example, it writes JSON data via JSONObject and JSONArray, and save it into a file named f test. Json. Simple. Write. Example. java. package com. JSONArray. import org. JSONObject. import java. File. Writer. import java. IOException. public class Json. Simple. Write. Example. String args. JSONObject obj new JSONObject. Integer1. 00. JSONArray list new JSONArray. File. Writer file new File. Writerf test. JSONString. IOException e. Stack. Trace. System. Outputf test. Read JSON from file. Use JSONParser to read above generated JSON file f test. Json. Simple. Read. Example. java. package com. JSONArray. import org. JSONObject. import org. JSONParser. import org. Parse. Exception. File. Not. Found. Exception. import java. File. Reader. import java. IOException. import java. Iterator. public class Json. Simple. Read. Example. String args. JSONParser parser new JSONParser. Object obj parser. File. Readerf test. JSONObject json. Object JSONObject obj. System. out. printlnjson. Object. String name String json. Object. getname. System. Long json. Object. System. out. printlnage. JSONArray msg JSONArray json. Object. getmessages. Iteratorlt String iterator msg. Next. System. File. Not. Found. Exception e. Stack. Trace. catch IOException e. Stack. Trace. catch Parse. Exception e. e. Stack. Trace. name mkyong. References. JSON. JSON. simple encoding JSON example. JSON. simple decoding JSON example.