How to get all imports defined in a class using java reflection?

Question

Hi i am new in java reflection domain.So can anyone guide me in this problem scenario.

I have a class named "SomClass.java" and it imports a package named "SomPackage.RefClass" And some other java libraries like java.lang.. etc.

Now i wish to get know all the imports defined in a class through reflection.

import SomPackage.RefClass;
import java.lang.reflect.Field;
import java.io.IOException; 
 public class SomeClass{
  RefClass refClass_Obj;
  String nationality;
///some other members
}

I just wanna know the list of all import defined in a class using reflection.

I have seen a Question posted hear similar to my Q but it is not well elaborated so,need some good direction of help.

thanks in advance.

See here (http://stackoverflow.com/questions/17928121/get-list-of-necessary-classes-for-a-class-to-load) for an answer which doesn't use reflection, or source code parsing, but bytecode reading instead. — carlspring, Jul 30 '13 at 09:55

score 17 · Accepted Answer · answered Apr 18 '11 at 10:27

17

I just wanna know the list of all import defined in a class using reflection

You can't because the compiler doesn't put them into the object file. It throws them away. Import is just a shorthand to the compiler.

answered Apr 18 '11 at 10:27

user207421

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As u explain "You can't because the compiler doesn't put them into the object file." I have try this and when i decompile a java file using some java Decompiler like DJ Java Decompiler.it will show all the imports(java libraries & as well packages).Can u explain this more? – zaree Apr 18 '11 at 11:19
2

@zaree No it won't. It will synthesize import statements for all the classes from other packages used by this class. It is not recreating the original source code. – user207421 May 20 '11 at 00:27

score 15 · Answer 2 · answered Apr 18 '11 at 10:09

15

Imports are a compile-time feature - there's no difference to the compiled code between a version which uses the full name of the type everywhere it's mentioned, a version which imports everything using a *, and a version which imports classes by full name.

If you want to find all the types used within the compiled code, that's a slightly different matter. You may want to look at BCEL as a way of analyzing bytecode.

answered Apr 18 '11 at 10:09

Jon Skeet

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@zaree - for completeness, there is no way to determine the types used within a type using the reflection APIs. – Stephen C Apr 18 '11 at 11:26

score 7 · Answer 3 · edited Apr 13 '19 at 22:10

7

I think you can use Qdox to get all the imports in a class which is not actually through reflection, but it can serve your purpose :

    String fileFullPath = "Your\\java\\ file \\full\\path";
    JavaDocBuilder builder = new JavaDocBuilder();
    builder.addSource(new FileReader( fileFullPath  ));

    JavaSource src = builder.getSources()[0];
    String[] imports = src.getImports();

    for ( String imp : imports )
    {
        System.out.println(imp);
    }

edited Apr 13 '19 at 22:10

ThisClark

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answered Jul 10 '12 at 09:04

Asraful Haque

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No you can't. From your own link: 'QDox is a high speed, small footprint parser for extracting class/interface/method definitions from *source* files ...' [emphasis added] – user207421 Jan 07 '15 at 17:12
5

Yes you are right, through reflection its not possible. But with Qdox its possible to get from .java file which might be useful for some others. – Asraful Haque Jan 28 '15 at 06:32

score 0 · Answer 4 · answered Mar 22 '22 at 17:30

As suggested by @Asraful Haque qdox helps to read imports of java file

Use Maven dependency

        <dependency>
            <groupId>com.thoughtworks.qdox</groupId>
            <artifactId>qdox</artifactId>
            <version>2.0.1</version>
        </dependency>

Please refer modified version of code

package readimports;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Collection;
import java.util.List;

import com.thoughtworks.qdox.JavaProjectBuilder;
import com.thoughtworks.qdox.model.JavaSource;

public class TestReadAllImport {

    public static void main(String[] args) throws FileNotFoundException {
        String fileFullPath = "path to java file";
        JavaProjectBuilder builder = new JavaProjectBuilder();
        builder.addSource(new FileReader( fileFullPath  ));

        Collection<JavaSource> srcs = builder.getSources();
        for(JavaSource src : srcs) {
            List<String> imports = src.getImports();

            for ( String imp : imports )
            {
                System.out.println(imp);
            }
        }
    }

}

How to get all imports defined in a class using java reflection?

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