I have a text (.txt) file that contains Java code! I want to create a method that includes this Java code and then call that method through the program.
Can anybody suggest a way to do this?
let consider this example what it does actually load the source code, compile and execute the java code by simpler program by using JavaCompiler API.
Use the JavaCompiler. It can compile code from a String, so I'm sure it could handle code from a text file.
Do you think instead of putting it in the main method I can put it in for example test method and call method like this?
Put it wherever you like. E.G. see the STBC & especially the source code. It provides a GUI and can compile the code in the text area on button click.
this program need tools.jar but jre 7 doesnt have this!!
Did you try reading the documentation that is provided for the STBC? Notably:
System Requirements
STBC will run on any computer with a version 1.6+ Java Plug-In* JDK (AKA SDK).
(*) The API that STBC uses is merely a public interface to the compiler in the tools.jar that is distributed only with JDKs (though the 'public JRE' of the JDK also seems to acquire a tools.jar). This leads to some unusual requirements in running either the native jar, or the web start app.
Or shorter, no JRE will have a JavaCompiler, only JDKs have them.
Change the .txt file to a .java file,
add it to your java project
Compile the code
Execute the methods
Load the file in through standard java IO and then have Groovy evaluate it for you:
http://groovy.codehaus.org/Embedding+Groovy
it's something like quine:
http://www.nyx.org/%7Egthompso/quine.htm
Related
I have a Java class which uses a .jar file.
Every time that I want to compile this class, I have to do something like javac -cp ".:myJar.jar" myClass.java and every time that I want to execute it, I have to do the similar thing but with java instead of javac.
Is there a way to avoid doing this?
I know that I could put this jar file into my class path but I don't want to do that. I don't neither want to do a maven projet.
There is nothing preventing you from using an IDE, taking advantage of all its super useful features when developing the program, and then submit just the source code and associated jars to the professor.
Advantages of using IDE that your professor don't need:
Syntax color-coded editors with auto-complete.
Built-in display of javadoc, so you know what all the built-in Java methods do, and how they work.
Instant high-lighting of syntax errors.
Never having to compile the code, since IDE always keeps the code compiled.
Easy single-button execution of the program when you want to run it.
Debugger. Very important feature when your code is not working as you intended.
... more ...
I found a traffic light simulator called Green Light District
the file I download included and explanation of how to build the project
and it says the following
Extract the archive to a certain directory,
In that dir do javac gld/*.java
In that dir do java gld.GLDSim
I know * means all but...
first I want to know am I able to compile something like *.java
this is a link to the simulator , if some one can tell how to compile it , it would be really nice
http://sourceforge.net/projects/stoplicht/
The issue occurs due to the fact that "enum" became reserved word in Java 1.5+, so it can no longer be used as a name for variables/methods/classes, but GLD uses enum as a name for some variables.
Once the name is changed - project will compile.
Alternatively one can try to compile it with compiler setting source version 1.4 - this should probably also work, but I suggest to simply rename all variables named enum.
Basically, all the code is in the folder called gld. You need to compile all the .java files inside it. After that, you run the main class gld.GLDSim.
Had the same problem.
You should use Java 1.4, this simulator is quite old, hence uses an old version of Java and some preserved words in more advanced Java versions.
I mean the intel assembly for the processor?
If you want to see the native code generated (at runtime) by the JIT compiler, then there are a series of JVM flags that will print the assembly code as it is generated.
They are included in this listing - search for "PrintAssembly".
Note that these options need to be prefixed with "-XX:" in the java command line. Refer to the java manual page for details.
You won't get anything like that. Java is compiled to ByteCode.
Java-code is translated to bytecode. Then the JVM takes the bytecode and executes it. So I think you are out of luck.
If you want the bytecode - see javap. It ships with the JDK and disassembles a class file. As #arjan noted, Eclipse shows such information when you double-click a class.
http://java.decompiler.free.fr/
but I guess that's extra easy to be found oneself.
If with "assembly translation" you mean the byte code (the output from Javac, JDT, etc) then the answer is really simple: find a .class file and double click on it.
This will show you the byte code in human readable mnemonics.
Enter the output folder - usually "bin" - in the Navigation perspective. There you can see all your class files.
Is there a way to run or simulate running Java statements (kind of like IDLE - the Python GUI) without compiling and running the executable? I want to quickly test statements to see if they work. Thanks.
Yep, you can use Eclipse, create a single project, and create a Scrapbook Page in that project.
You can also specify import statements: http://www.informit.com/articles/article.aspx?p=31789&seqNum=3
Scrapbook pages get their classpath
from the containing project's build
path. If in a scrapbook page you want
to reference a Java element that is
not on the build path of the
containing Java project, you need to
add to the Java project's build path.
Scrapbook pages also allow you to
specify import statements. You do this
by selecting Set Imports from the
context menu of a scrapbook page or
Set Import Declarations for Running
Code from the toolbar. You need to set
import statements for references to
Java declarations in your projects.
This is a common oversight. If the
type or package you are attempting to
import is not listed in the Add
dialog, it means you need to add it to
the build path of the project
containing the scrapbook page. If you
are referencing an element that has
multiple declarations, you will need
to add an import statement to uniquely
identify the element.
Edit: Got another solution too: http://ideone.com. It's an online IDE and debugging tool. You can see an example here: http://ideone.com/98sA8, but it looks like you have to set up a bit more than on a scrapbook page.
Edit 2:
Nowadays in Java 11, if it's a simple app in a single file you can run it directly from the java command (on the command line) which will handle all the compilation for you behind the scenes:
java HelloWorld.java
This is useful for students, as they can get started with Java without learning all of the javac compilation routine.
As of Java 11 (JEP 330) it is now possible to run Java files directly with the java tool:
java Factorial.java 3 4 5
is informally equivalent to
javac -d <memory> Factorial.java
java -cp <memory> Factorial 3 4 5
Java also added support for "shebang" files.
For more details see:
http://openjdk.java.net/jeps/330
Using Eclipse, you can create a Scrapbook page which will allow you to do exactly this.
Caveats:
You need to use full binary class names for anything outside of java.lang
You need to select the code (standard text selection) that you want to run
There are three different methods for running -- Inspect, Display, and Run. Inspect and Display are virtually the same, showing you the result of the last statement in your code (so you don't need to print it or anything), Run runs the selected code and dumps any output to the console view.
Never used it, but BeanShell seems to do what you want
You should be able to use Beanshell to do this:
http://www.beanshell.org/download.html
Your other alternative, if you're using Eclipse, is to make use of the scrapbook functionality:
http://help.eclipse.org/helios/index.jsp?topic=/org.eclipse.jdt.doc.user/tasks/task-create_scrapbook_page.htm
You can accomplish this with Groovy and the Groovy Console, with the caveat that you'd need to know how to express whatever you are trying to express in Java in the Groovy language:
you might want to checkout janino http://docs.codehaus.org/display/JANINO/Home also ..
JGrasp is the best solution. There is a thing called interactions, that's perfectly fine.
Use JShell, which is included by default starting from JDK 9. It is command-line based Read Eval Print Loop (REPL), where you can enter Java code, and get the results immediately.
I have a java program that I'm required to compile into a Linux native program using gcj-4.3. This program requires serial port access. The javax.comm api provides serial port access but I'm not sure how to get my compiled java program to use it.
The target box has Java installed, but of course my compiled program isn't running in the JRE...so I'm not exactly sure how I can link in the comm.jar file or how that file can find the .properties file it requires.
I wonder if I can just compile the comm.jar allong with my .jar file and link the two object files together. Can my code then reference the classes in comm.jar?
Thanks in advance for your help!
I'm not an GCJ expert but I have some suggestions (I'm not providing the syntax, this will require some exploration that I didn't perform):
first, I think that you'll have to compile comm.jar into a (shared) library,
then, you'll have to link your code against the library,
finally, use the GCJ_PROPERTIES environment variable to pass properties to the program at invocation time.
The following pointers might be helpful to implement this:
GCJ---The GNU Compiler for Java (great resources IMO, covers all the steps mentioned above)
GCJ – Getting Started (more an intro but still nice)
Compile ActiveMQ with GCJ (more use cases but I don't think they apply here)
And of course, the official documentation :)