The following will create an AST for each source file in your workspace and print out the name and the return type of each method using the AST.

Create a new plugin project "de.vogella.jdt.astsimple" using the "Hello world" template.

Maintain the following plugin dependencies.

			
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Astsimple Plug-in
Bundle-SymbolicName: de.vogella.jdt.astsimple;singleton:=true
Bundle-Version: 1.0.0
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Require-Bundle: org.eclipse.core.runtime;bundle-version="3.4.0",
 org.eclipse.ui;bundle-version="3.4.2",
 org.eclipse.jdt.core;bundle-version="3.4.4",
 org.eclipse.core.resources;bundle-version="3.4.2",
 org.eclipse.jdt.ui;bundle-version="3.4.2"

		

To get information about the AST you can use the Visitor Pattern. This allows you to add a visitor to the AST for a specific elements. In this visitor can you capture information about the object and return it after processing the AST. Create for this the following class.

			
package de.vogella.jdt.astsimple.handler;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.MethodDeclaration;

public class MethodVisitor extends ASTVisitor {
	List<MethodDeclaration> methods = new ArrayList<MethodDeclaration>();

	@Override
	public boolean visit(MethodDeclaration node) {
		methods.add(node);
		return super.visit(node);
	}

	public List<MethodDeclaration> getMethods() {
		return methods;
	}
}

		

Add a new command "de.vogella.jdt.astsimple.GetInfo" and put it into the menu.

Create the following handler for this command.

			
package de.vogella.jdt.astsimple.handler;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IPackageFragment;
import org.eclipse.jdt.core.IPackageFragmentRoot;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.MethodDeclaration;

public class GetInfo extends AbstractHandler {

	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {
		IWorkspace workspace = ResourcesPlugin.getWorkspace();
		IWorkspaceRoot root = workspace.getRoot();
		// Get all projects in the workspace
		IProject[] projects = root.getProjects();
		// Loop over all projects
		for (IProject project : projects) {
			try {
				if (project.isNatureEnabled("org.eclipse.jdt.core.javanature")) {

					IPackageFragment[] packages = JavaCore.create(project)
							.getPackageFragments();
					// parse(JavaCore.create(project));
					for (IPackageFragment mypackage : packages) {
						if (mypackage.getKind() == IPackageFragmentRoot.K_SOURCE) {
							for (ICompilationUnit unit : mypackage
									.getCompilationUnits()) {
								// Now create the AST for the ICompilationUnits
								CompilationUnit parse = parse(unit);
								MethodVisitor visitor = new MethodVisitor();
								parse.accept(visitor);

								for (MethodDeclaration method : visitor
										.getMethods()) {
									System.out.print("Method name: "
											+ method.getName()
											+ " Return type: "
											+ method.getReturnType2());
								}

							}
						}

					}
				}
			} catch (CoreException e) {
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * Reads a ICompilationUnit and creates the AST DOM for manipulating the
	 * Java source file
	 * 
	 * @param unit
	 * @return
	 */

	private static CompilationUnit parse(ICompilationUnit unit) {
		ASTParser parser = ASTParser.newParser(AST.JLS3);
		parser.setKind(ASTParser.K_COMPILATION_UNIT);
		parser.setSource(unit);
		parser.setResolveBindings(true);
		return (CompilationUnit) parser.createAST(null); // parse
	}
}

		

Add the command to your menu. Run your new plugin, create a new Java project and select the command. It should print out the information about your methods in the IDE from which you started your new plugin