Could someone please help me to create rule in pmd for eclipse? I am unable to start even i followed through PMD official site. I am planning to create rule in java instead of XPath rule. Any simple guidelines to start it?
Thanks
Try the 'Write a rule using Java' method as you can easily start this way and later you can try with XPath expressions. You can follow these steps alongside the official link.
Start with the src package that comes with PMD (e.g. pmd-4.2.x\src), create your java class inside an existing package (e.g. pmd-4.2.5\src\net\sourceforge\pmd\rules\basic). In this case it is the following sample code (WhileLoopsMustUseBracesRule) :
package net.sourceforge.pmd.rules.basic;
import net.sourceforge.pmd.*;
import net.sourceforge.pmd.ast.*;
public class WhileLoopsMustUseBracesRule extends AbstractRule {
public Object visit(ASTWhileStatement node, Object data) {
SimpleNode firstStmt = (SimpleNode)node.jjtGetChild(1);
if (!hasBlockAsFirstChild(firstStmt)) {
addViolation(data, node);
}
return super.visit(node,data);
}
private boolean hasBlockAsFirstChild(SimpleNode node) {
return (node.jjtGetNumChildren() != 0 && (node.jjtGetChild(0) instanceof ASTBlock));
}
}
Append the following rule inside basic.xml(pmd-4.2.5\rulesets\basic.xml) :
Copy paste the xml content from "Put the WhileLoopsMustUseBracesRule rule in a ruleset file" section to basic.xml.
Replace the line
class="WhileLoopsMustUseBracesRule">
with
class="net.sourceforge.pmd.rules.basic.WhileLoopsMustUseBracesRule">
as you must have created the java file (WhileLoopsMustUseBracesRule.java) inside package "net.sourceforge.pmd.rules.basic"
Run this command from cmd prompt if in windows.
pmd.bat C:\JAVAFILE_ON_WHICH_YOU_WANT_TO_RUN_THIS_RULE xml C:\PMD\pmd-4.2.5\pmd-4.2.5\rulesets\basic.xml
For the nix os (linux/MacOS), use pmd.sh instead of pmd.bat
Once you are able to get it running, you can create your own rule inside your own package.
Hope this helps.!
I wrote a tutorial a while back with some sample code that could be helpful.
http://www.techtraits.ca/writting-pretty-code-with-pmd/
Related
Executing the gradle application plugin's installDist task creates a directory build/install/my-application-name/bin that contains wrapper scripts, my-application-name and my-application-name.bat. Running either of these scripts runs the application, and arguments passed to these scripts are passed to the underlying application.
In UNIX shell scripts you can access the name that was used to execute the program as $0. In fact, the UNIX version of the gradle-generated startup script uses $0 several times.
How can I configure the gradle application plugin such that these scripts will pass the value of $0 (and whatever the Windows equivalent is on Windows) into the underlying application, perhaps as a Java system property?
Since parameter for obtaining the name of the script being run is referenced differently in Linux($0) and in Windows(%0), the most straightforward way to generate custom scripts would be to use separate custom templates for the respective start script generators:
startScripts {
unixStartScriptGenerator.template = resources.text.fromFile('unixStartScript.txt')
windowsStartScriptGenerator.template = resources.text.fromFile('windowsStartScript.txt')
}
The default templates are easy to obtain invoking e.g. unixStartScriptGenerator.template.asString()
Documentation on customizing the start scripts can be found here.
This is what I ended up doing, based on jihor's answer. I'm posting it here just so that there's a working answer for anyone else interested:
startScripts {
def gen = unixStartScriptGenerator
gen.template = resources.text.fromString(
gen.template.asString().replaceFirst('(?=\nDEFAULT_JVM_OPTS=.*?\n)') {
'\nJAVA_OPTS="\\$JAVA_OPTS "\'"-Dprogname=\\$0"\''
})
// TODO: do something similar for windowsStartScriptGenerator
}
This uses replaceFirst is instead of replace so we can match a pattern. This is a little less brittle, and also lets us use lookahead so we don't have to actually replace what we're looking for. (This is groovy's variant of replaceFirst that takes a closure, by the way. This requires far less escaping than the version that takes a replacement string in this case.)
Also, instead of:
JAVA_OPTS="$JAVA_OPTS -Dprogname=$0"
we actually need something like:
JAVA_OPTS="$JAVA_OPTS "'"-Dprogname=$0"'
This is because $0 may contains special character (like spaces), and the startup script removes one level of quoting in the value of $JAVA_OPTS using eval set --.
(If anyone knows how to make this work on Windows, pleas feel free to update this answer.)
I took an alternative approach. According to the documentation, as far back as Gradle 2.4 and all the way through Gradle 4.8, we should be able to set the following properties within the startScripts task:
applicationName
optsEnvironmentVar
exitEnvironmentVar
mainClassName
executableDir
defaultJvmOpts
appNameSystemProperty
appHomeRelativePath
classpath
Unfortunately, this is not true for the following properties, which seem to have never been exposed:
appNameSystemProperty
appHomeRelativePath
If appNameSystemProperty were exposed as the documentation describes, then we should be able to simply do the following:
startScripts {
applicationName = 'foo'
appNameSystemProperty = 'appName'
}
This would then result in the addition of -DappName=foo to the Java command constructed within both of the start scripts.
Since this is not the case, I took the following approach, which is a bit more verbose than the earlier solution to this question, but is perhaps less brittle because it does not rely on tweaking the out-of-box templates. Instead, it results in the documented behavior.
startScripts {
mainClassName = '...'
applicationName = 'foo'
unixStartScriptGenerator =
new CustomStartScriptGenerator(generator: unixStartScriptGenerator)
windowsStartScriptGenerator =
new CustomStartScriptGenerator(generator: windowsStartScriptGenerator)
}
class CustomStartScriptGenerator implements ScriptGenerator {
#Delegate
ScriptGenerator generator
void generateScript(JavaAppStartScriptGenerationDetails details,
Writer destination) {
details = new CustomDetails(details: details)
this.generator.generateScript(details, destination)
}
static class CustomDetails implements JavaAppStartScriptGenerationDetails {
#Delegate
JavaAppStartScriptGenerationDetails details
#Override
String getAppNameSystemProperty() { 'appName' }
}
}
My project requires Java 1.6 for compilation and running. Now I have a requirement to make it working with Java 1.5 (from the marketing side). I want to replace method body (return type and arguments remain the same) to make it compiling with Java 1.5 without errors.
Details: I have an utility class called OS which encapsulates all OS-specific things. It has a method
public static void openFile(java.io.File file) throws java.io.IOException {
// open the file using java.awt.Desktop
...
}
to open files like with double-click (start Windows command or open Mac OS X command equivalent). Since it cannot be compiled with Java 1.5, I want to exclude it during compilation and replace by another method which calls run32dll for Windows or open for Mac OS X using Runtime.exec.
Question: How can I do that? Can annotations help here?
Note: I use ant, and I can make two java files OS4J5.java and OS4J6.java which will contain the OS class with the desired code for Java 1.5 and 1.6 and copy one of them to OS.java before compiling (or an ugly way - replace the content of OS.java conditionally depending on java version) but I don't want to do that, if there is another way.
Elaborating more: in C I could use ifdef, ifndef, in Python there is no compilation and I could check a feature using hasattr or something else, in Common Lisp I could use #+feature. Is there something similar for Java?
Found this post but it doesn't seem to be helpful.
Any help is greatly appreciated. kh.
Nope there isn't any support for conditional compilation in Java.
The usual plan is to hide the OS specific bits of your app behind an Interface and then detect the OS type at runtime and load the implementation using Class.forName(String).
In your case there no reason why you can't compile the both OS* (and infact your whole app) using Java 1.6 with -source 1.5 -target 1.5 then in a the factory method for getting hold of OS classes (which would now be an interface) detect that java.awt.Desktop
class is available and load the correct version.
Something like:
public interface OS {
void openFile(java.io.File file) throws java.io.IOException;
}
public class OSFactory {
public static OS create(){
try{
Class.forName("java.awt.Desktop");
return new OSJ6();
}catch(Exception e){
//fall back
return new OSJ5();
}
}
}
Hiding two implementation classes behind an interface like Gareth proposed is probably the best way to go.
That said, you can introduce a kind of conditional compilation using the replace task in ant build scripts. The trick is to use comments in your code which are opened/closed by a textual replacement just before compiling the source, like:
/*{{ Block visible when compiling for Java 6: IFDEF6
public static void openFile(java.io.File file) throws java.io.IOException {
// open the file using java.awt.Desktop
...
/*}} end of Java 6 code. */
/*{{ Block visible when compiling for Java 5: IFDEF5
// open the file using alternative methods
...
/*}} end of Java 5 code. */
now in ant, when you compile for Java 6, replace "IFDEF6" with "*/", giving:
/*{{ Block visible when compiling for Java 6: */
public static void openFile(java.io.File file) throws java.io.IOException {
// open the file using java.awt.Desktop
...
/*}} end of Java 6 code. */
/*{{ Block visible when compiling for Java 5, IFDEF5
public static void openFile(java.io.File file) throws java.io.IOException {
// open the file using alternative methods
...
/*}} end of Java 5 code. */
and when compiling for Java 5, replace "IFDEF5". Note that you need to be careful to use // comments inside the /*{{, /*}} blocks.
You can make the calls using reflection and compile the code with Java 5.
e.g.
Class clazz = Class.forName("java.package.ClassNotFoundInJavav5");
Method method = clazz.getMethod("methodNotFoundInJava5", Class1.class);
method.invoke(args1);
You can catch any exceptions and fall back to something which works on Java 5.
The Ant script introduced below gives nice and clean trick.
link: https://weblogs.java.net/blog/schaefa/archive/2005/01/how_to_do_condi.html
in example,
//[ifdef]
public byte[] getBytes(String parameterName)
throws SQLException {
...
}
//[enddef]
with Ant script
<filterset begintoken="//[" endtoken="]">
<filter token="ifdef" value="${ifdef.token}"/>
<filter token="enddef" value="${enddef.token}"/>
</filterset>
please go to link above for more detail.
In java 9 it's possible to create multi-release jar files. Essentially it means that you make multiple versions of the same java file.
When you compile them, you compile each version of the java file with the required jdk version. Next you need to pack them in a structure that looks like this:
+ com
+ mypackage
+ Main.class
+ Utils.class
+ META-INF
+ versions
+ 9
+ com
+ mypackage
+ Utils.class
In the example above, the main part of the code is compiled in java 8, but for java 9 there is an additional (but different) version of the Utils class.
When you run this code on the java 8 JVM it won't even check for classes in the META-INF folder. But in java 9 it will, and will find and use the more recent version of the class.
I'm not such a great Java expert, but it seems that conditional compilation in Java is supported and easy to do. Please read:
http://www.javapractices.com/topic/TopicAction.do?Id=64
Quoting the gist:
The conditional compilation practice is used to optionally remove chunks of code from the compiled version of a class. It uses the fact that compilers will ignore any unreachable branches of code.
To implement conditional compilation,
define a static final boolean value as a non-private member of some class
place code which is to be conditionally compiled in an if block which evaluates the boolean
set the value of the boolean to false to cause the compiler to ignore the if block; otherwise, keep its value as true
Of course this lets us to "compile out" chunks of code inside any method. To remove class members, methods or even entire classes (maybe leaving only a stub) you would still need a pre-processor.
if you don't want conditionally enabled code blocks in your application then a preprocessor is only way, you could take a look at java-comment-preprocessor which can be used for both maven and ant projects
p.s.
also I have made some example how to use preprocessing with Maven to build JEP-238 multi-version JAR without duplication of sources
Java Primitive Specializations Generator supports conditional compilation:
/* if Windows compilingFor */
start();
/* elif Mac compilingFor */
open();
/* endif */
This tool has Maven and Gradle plugins.
hi I have got similar problem when I have shared library between Java SDK abd Android and in both environments are used the graphics so basically my code must to work with both
java.awt.Graphics and android.graphics.Canvas,
but I don't want to duplicate almost any code.
My solution is to use wrapper, so I access to graphisc API indirectl way, and
I can change a couple of imports, to import the wrapper I want to compile the projects.
The projects have some cone shaded and some are separate, but there is no duplicating anything except of couple of wrappers etc.
I think it is the best what I can do.
This question is Java and Maven specific. Please note the additional constraints below as they are different from other questions.
I have several Maven (Java) projects to analyze. What I have is:
the source code
maven-compiled Jave code with binaries in target/ folder
The question is:
Given one source code file (.java) and a line number there, how can I get the fully qualified name of the method that spans over that line? If the line is not in a method then just output null. Acceptable languages to implement this are: Java, ruby, or python.
Could you please answer the question in one of the following two ways?
use the binary and extract qualified method name of that line. (This might involve weave in debug info, but that is fine.)
directly use the source file given, try to parse it and use the AST.
Using specific libraries (like BCEL) or any 3rd party ones (as long as they are well documented and usable) are OK, too.
Many many thanks for the huge help!
Unfortunately, your question is full of drawbacks:
You could, of corse, parse the input source (through an Javacc or ANTLR parser) until you reach the desired line. But it seems a waste of effort to parse the same source since you already have the .class files.
So, it seems better to analyze the .class file. But unfortunately, you have no gurantee that this is the class where your line spawns at, because there can be more than one class defined in the same source file.
Augh! That leads me to a kind of complicated solution:
I'll declare a class which will contain all the login:
public class SourceMethodsIndexer
{
private final SortedMap<Integer, List<Method>> indexOfMethodsByFirstLineNumber;
}
The constructor will be like this:
public SourceMethodsIndexer(File sourceFile)
... and should do these tasks:
1.Browse the class directory related to the target package.
File targetPackageDir=getTargetPackageDir(sourceFile);
File[] classFiles=targetPackageDir.listFiles(new FileFilter(){
public boolean accept(File dir, String name){
return name.endsWith(".class");
}
});
2.Use Apache BCEL to collect all the non public classes belonging to your input source file (you can invoke JavaClass.getSourceFileName() to filter classes), plus the public class corresponding to the name of your input source file.
Collection<JavaClass> targetClasses=getNonPublicClasses(classFiles, sourceFile.getName());
targetClasses.add(publicClass);
3.Collect then all the methods in each class.
Set<Method> targetMethods=new HashSet<Method>(1024);
for (JavaClass javaClass:targetClasses)
{
targetMethods.addAll(Arrays.asList(javaClass.getMethods()));
}
4.Now you can either search directly your line number, or index first the methods by line number to access them later more quickly: JavaClass.getMethods()[n].getLineNumberTable().getSourceLine(0) (take care that there could be repeated values).
this.indexOfMethodsByFirstLineNumber=new TreeMap<Integer, List<Method>>((int)(1.7d*methods.size()));
for (Method method: methods)
{
// Note: The -1 in this line stands to make the SortedMap work properly when searching for ranges.
int firstLine=getLineNumberTable().getSourceLine(0)-1;
List<Method> methodsInTheSameLine=indexOfMethodsByFirstLineNumber.get(firstLine);
if (methodsInTheSameLine==null)
{
methodsInTheSameLine=new ArrayList<Method>();
indexOfMethodsByFirstLineNumber.put(firstLine,methodsInTheSameLine);
}
methodsInTheSameLine.add(method);
}
5.Public a method to do the search:
public Method getMethodByLine(int lineNumber)
{
Set<Method> methodsInTheSameLine=this.indexOfMethodsByFirstLineNumber.headMap(lineNumber).lastKey();
if (methodsInTheSameLine.size()==0)
{
// There are no methods method in that line: Absurd.
}
else if (methodsInTheSameLine.size()>1)
{
// There are more than one method in that line. Hardly probable, but possible.
}
else
{
// There is one method in that line:
return methods.get(0);
}
}
There are a number of open source Maven plugins which analyse source code, and report on a per-method basis. A careful study of some of those may be your best bet.
Examples include Checkstyle, FindBugs, PMD, JDepend, JavaNCSS.
Also take a look at SonarQube.
I've been struggling with this problem for two days now and no resource I've found have been able to solve it.
I am trying to call a java class (added the link at the bottom) from Matlab (version 7.13.0.564 (R2011b)). I've compiled the java class using java 1.6 into a .class file and also added the path to the folder where the file is situated using javaaddpath (I've of course checked that the path is correct in the list of dynamic paths). However, when I try to call the class from Matlab using javaMethod('main','PerlinNoiseGenerator','') I get the error:
"No class PerlinNoiseGenerator can be located on Java class path"
I would be extremely grateful if someone with experience in calling java from Matlab could put together a short tut on how to do this. I am probably going to distribute my code so I kinda need to set the java path dynamically and from what I've read it really should be possible although I've seen post that indicate that it could be the cause of the problem.
http://svn.j3d.org/code/tags/Xj3D-M10/src/java/org/j3d/texture/procedural/PerlinNoiseGenerator.java
Usually I create jar files that contain java classes. I also had problems loading individual java classes before. In your case I did the following on xubuntu 13.04 x64 and Matlab 2013a x64 to load your particular class:
Compile it using java 6 (not the default 7) with option -d . to create a set of package folders, as your class defines a package org/j3d/texture/proecedural/ etc:
/usr/lib/jvm/java-6-openjdk-amd64/bin/javac -d . PerlinNoiseGenerator.java
This will compile the class and make in the current director (thus .) the set of package folders.
Make jar file containing your class again using jar from java 6. I named it javaNoise.jar:
/usr/lib/jvm/java-6-openjdk-amd64/bin/jar cf javaNoise.jar ./org/j3d/texture/procedural/PerlinNoiseGenerator.class
In Matlab, in the directory where javaNoise.jar is:
javaaddpath('./javaNoise.jar');
Create object of your java class:
png=org.j3d.texture.procedural.PerlinNoiseGenerator()
% results in: png = org.j3d.texture.procedural.PerlinNoiseGenerator#3982a033
To test it, I just generated some 1D noise:
png.noise1(1.2)
ans = -0.0960
Hope this helps.
P.S.
javaMethod('main','PerlinNoiseGenerator','') wont work because this class has no main method:-).
Your notation to the compiler of the constructor is a polymorphic class meaning "use appropriate constructor that is called at runtime".
public PerlinNoiseGenerator()
public PerlinNoiseGenerator(int seed)
The first form with no argument can be called but is irrelevent because the line with this(DEFAULT_SEED) attempts to call itself but only one constructor is allowed used
Second constructor has int for an argument but requires being loaded by an already loaded class.
Use the first version and change the case sensitive name of the one with the argument and remove this(DEFAULT_SEED) from it replace with the method name(the one you changed from a constructor that has the argument).
e.g. public perlinNoiseGenerator(int seed)
note: by convention java code method names start with a lower-case letter.
A final note, java arguments from the command line come in as "String" data type through the "main" method, a starter method for applications (gui or command prompt).
The first argument on the main method argument is the first commandline argument.
public static void main(String[] Args){
new PerlinNoiseGenerator(Args); // recursive class call
}//end main method
int[] args; // global
public PerlinNoiseGenerator(String[] Args){
int arglength=Args.length();
args = new int[arglength];
for(int cnt=0;cnt<arglength;cnt++){
Args[cnt].trim();
args[cnt]=new Integer(Args[cnt]).intValue();
}//enfor
perlinNoiseGenerator(args[0]); // call method
}//end constructor
I have a .java file which contains a class. I want to add a method to that class but I can't find a real useful "HOWTO" or examples around.
I'm using Eclipse and its JDT plugin for AST.
I tried a code that creates an ICompilationUnit from a project
IProject project = ResourcesPlugin.getWorkspace().getRoot().getProject("ProjName");
IJavaProject javaProject = JavaCore.create(project);
IPackageFragment package1 = javaProject.getPackageFragments()[0];
ICompilationUnit unit = package1.getCompilationUnits()[0];
then add a method with astrewrite.
But it seems to work only if I run all as a Plugin Project and not a simple Java Application.
I need to write an application in java that "simply" parse a java file and adds method to its class.
What I supposed to do is:
1) Create an ICompilationUnit directly form the .java file I want to parse (eventually located in my own project's directory)
2) Using another way
Both case I can't go further. Anyone can help me?
When you need to make a change by adding something to the compilation unit, you will have to use the functions provided by CompilationUnit to create new nodes.
To add a method to "unit" you will have to :
Create a MethodDeclaration node using your compilation unit :
MethodDeclaration md = unit.getAST().newMethodDeclaration();
Customize this method declaration to your requirements :
md.setName( unit.getAST().newSimpleName( "newMethod" ) );
md.setBody( unit.getAST().newBlock() );
this will produce : void newMethod() {}
Obtain the TypeBinding from "unit" :
TypeDeclaration typeDeclaration = ( TypeDeclaration )unit.types().get( 0 );
Add your newly created MethodDeclaration to the body declarations :
typeDeclaration.bodyDeclarations().add( md );
There's a method called getMethods() on TypeDeclaration but it doesn't return a live list of MethodDeclarations, therefore you can't modify that directly.
It's really easy to read the source file as text and replace the last } with the method declaration plus }. Obviously this doesn't work if someone puts multiple top-level classes in one file (which is extremely rare and I doubt you'll have a problem with that).