Get the list of imports

[kfranic]

Hi *,
let's say I have following code:

import java.util.Vector;

public class Test {
  public void printMe() {
    Vector<String> v = new Vector<String>();
    v.add("test");
    System.out.println(v.get(0));
  }
}

Does someone knows how can I get the list of imports, in this example only "java.util.Vector"?

I started with following, but I do not see how can I get required info:

ClassLoader classLoader = MainClass.class.getClassLoader();
Class aClass = classLoader.loadClass("Test");

Any ideas?

Thanks in advance!

[lovelesh]

Why don't you read the class as a string and then search all the lines which start with import.

I don't think java provides you any api for this :-(

[DarrylBurke]

imports are just syntactic sugar for the source code. Don't expect to be able to detect imports from the .class files.

If you need this, you will have to read and parse the source (i.e. .java) file. But why do you need this at all?

db

[kfranic]

Hi guys,
thanks for your input.
I've went with parsing .class file as string... This did the trick!

[JosAH]

Hi guys,
thanks for your input.
I've went with parsing .class file as string... This did the trick!

AFAIK there is no notion of 'imported' classes in a class file ...

kind regards,

Jos

[kfranic]

AFAIK there is no notion of 'imported' classes in a class file ...

kind regards,

Jos

Indeed.
I'm doing dumb parsing of the class file (like strings in UNIX) and only take the pattern I need.
Not very nice, but it works :)

[JosAH]

Indeed.
I'm doing dumb parsing of the class file (like strings in UNIX) and only take the pattern I need.
Not very nice, but it works :)

Ah, ok, you mean the .java source file.

kind regards,

Jos

[kfranic]

No I actually mean class file.
Try to run "strings" command on .class file...
I've noticed that few tings can't be parsed directly that way (e.g. "type a=Interface.constant"), but so far it works well enough.

Simple grep does not help as one can use imports with "*" or they can just type inline full class name with package... Grep source files approach for "import" keyword was no OK in my env. I would have to do a parser with lexer support for Java, etc... Too complicated for task at hand. Unless you (or some other reader) know of a GPL or similar licensed product that can parse source file (.java) with similar results I'd be interested... I guess Eclipse and e.g Net Beans have to do it somehow... But googling did not help, perhaps I've used wrong keywords...

[JosAH]

I would have to do a parser with lexer support for Java, etc... Too complicated for task at hand. Unless you (or some other reader) know of a GPL or similar licensed product that can parse source file (.java) with similar results I'd be interested... I guess Eclipse and e.g Net Beans have to do it somehow... But googling did not help, perhaps I've used wrong keywords...

You can use Javac'c API; if you go to the index page of the API documentation you'll see a 'wall' of bricks. Every brick mentions one of the available Java technologies in the SE suite. The top row, second brick from the left mentions 'javac'; click it and you'll see the entire javac API documentation. The idea is to have javac parse your source file(s) and process the AST (Abstract Syntax Tree) with an appropriate visitor. The visitor looks something like this:

class TreeVisitor extends TreePathScanner<Void, Void> {

	public Void visitCompilationUnit(CompilationUnitTree node, Void arg) {
		
		System.out.println("CompilationUnitTree: "+node);
		return super.visitCompilationUnit(node, arg);
	}

	public Void visitImport(ImportTree node, Void arg) {
		
		System.out.println("ImportTree: "+node);
		return super.visitImport(node, arg);
	}

	// more node visitora optionally here ...
}

It's the last method above you're interested in. Read the mentioned API documentation for the details. The AST definition is in package com.sun.source.tree.

kind regards,

Jos

[kfranic]

Thanks, I'll give it a try.