Question

I want to generate custom methods in Eclipse like the way we can generate toString, getters and settlers (right click -> source ->). Could anyone tell me what is involved in doing this?
Thanks,
Dutch

Answer 1

You could add your own action after the recent (Eclipse Galileo 3.5) generate toString() action,

• using the active contribution URI: menu:org.eclipse.jdt.ui.source.menu?after=additions
• with the active action definition identifier: org.eclipse.jdt.ui.edit.text.java.generate.tostring
• using the active contribution item class: GenerateToStringAction (package org.eclipse.jdt.ui.actions)
• from the contributing plugin: org.eclipse.jdt.ui

I cannot find the source of that class on the internet, so I will copy it here for you to examine its content:

/*******************************************************************************
 * Copyright (c) 2008, 2009 Mateusz Matela and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Mateusz Matela <[e-mail]> - [code manipulation] [dcr] toString() builder wizard - https://bugs.eclipse.org/bugs/show_bug.cgi?id=26070
 *     Mateusz Matela <[e-mail]> - [toString] toString() generator: Fields in declaration order - https://bugs.eclipse.org/bugs/show_bug.cgi?id=279924
 *******************************************************************************/
package org.eclipse.jdt.ui.actions;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import org.eclipse.swt.widgets.Shell;

import org.eclipse.core.resources.IWorkspaceRunnable;

import org.eclipse.ui.IWorkbenchSite;
import org.eclipse.ui.PlatformUI;

import org.eclipse.ltk.core.refactoring.RefactoringStatus;

import org.eclipse.jdt.core.IField;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IMember;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.dom.IBinding;
import org.eclipse.jdt.core.dom.IMethodBinding;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.IVariableBinding;
import org.eclipse.jdt.core.dom.Modifier;

import org.eclipse.jdt.internal.corext.codemanipulation.CodeGenerationSettings;
import org.eclipse.jdt.internal.corext.codemanipulation.tostringgeneration.GenerateToStringOperation;
import org.eclipse.jdt.internal.corext.codemanipulation.tostringgeneration.ToStringGenerationSettings;
import org.eclipse.jdt.internal.corext.util.JavaModelUtil;
import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.actions.ActionMessages;
import org.eclipse.jdt.internal.ui.actions.SelectionConverter;
import org.eclipse.jdt.internal.ui.dialogs.GenerateToStringDialog;
import org.eclipse.jdt.internal.ui.dialogs.SourceActionDialog;
import org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor;
import org.eclipse.jdt.internal.ui.viewsupport.BasicElementLabels;

/**
 * Adds method implementations for <code>{@link java.lang.Object#toString()}</code> The action opens a
 * dialog from which the user can choose the fields and methods to be considered.
 * <p>
 * Will open the parent compilation unit in a Java editor. The result is
 * unsaved, so the user can decide if the changes are acceptable.
 * <p>
 * The action is applicable to structured selections containing elements of type
 * {@link org.eclipse.jdt.core.IType}.
 * 
 * <p>
 * This class may be instantiated; it is not intended to be subclassed.
 * </p>
 * 
 * @since 3.5
 * 
 * @noextend This class is not intended to be subclassed by clients.
 */
public class GenerateToStringAction extends GenerateMethodAbstractAction {

    private static final String METHODNAME_TO_STRING= "toString"; //$NON-NLS-1$

    private List fFields;

    private List fInheritedFields;

    private List fSelectedFields;

    private List fMethods;

    private List fInheritedMethods;

    private GenerateToStringOperation operation;

    private class ToStringInfo {

        public boolean foundToString= false;

        public boolean foundFinalToString= false;

        public ToStringInfo(ITypeBinding typeBinding) {
            IMethodBinding[] declaredMethods= typeBinding.getDeclaredMethods();

            for (int i= 0; i < declaredMethods.length; i++) {
                if (declaredMethods[i].getName().equals(METHODNAME_TO_STRING) && declaredMethods[i].getParameterTypes().length == 0) {
                    this.foundToString= true;
                    if (Modifier.isFinal(declaredMethods[i].getModifiers()))
                        this.foundFinalToString= true;
                }
            }
        }
    }

    /**
     * Creates a new generate tostring action.
     * <p>
     * The action requires that the selection provided by the site's selection
     * provider is of type
     * {@link org.eclipse.jface.viewers.IStructuredSelection}.
     * 
     * @param site the workbench site providing context information for this
     *            action
     */
    public GenerateToStringAction(IWorkbenchSite site) {
        super(site);
        setText(ActionMessages.GenerateToStringAction_label);
        setDescription(ActionMessages.GenerateToStringAction_description);
        setToolTipText(ActionMessages.GenerateToStringAction_tooltip);
        PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.GENERATE_TOSTRING_ACTION);
    }

    /**
     * Note: This constructor is for internal use only. Clients should not call
     * this constructor.
     * 
     * @param editor the compilation unit editor
     * 
     * @noreference This constructor is not intended to be referenced by clients.
     */
    public GenerateToStringAction(CompilationUnitEditor editor) {
        this(editor.getEditorSite());
        fEditor= editor;
        setEnabled((fEditor != null && SelectionConverter.canOperateOn(fEditor)));
    }

    RefactoringStatus checkMember(Object object) {
        // no conditions need to be checked 
        return new RefactoringStatus();
    }

    RefactoringStatus checkGeneralConditions(IType type, CodeGenerationSettings settings, Object[] selected) {
        return operation.checkConditions();
    }

     RefactoringStatus checkSuperClass(ITypeBinding superclass) {
        RefactoringStatus status= new RefactoringStatus();
        if (new ToStringInfo(superclass).foundFinalToString) {
            status.addError(Messages.format(ActionMessages.GenerateMethodAbstractAction_final_method_in_superclass_error, new String[] {
                    Messages.format(ActionMessages.GenerateMethodAbstractAction_super_class, BasicElementLabels.getJavaElementName(superclass.getQualifiedName())),
                    ActionMessages.GenerateToStringAction_tostring }), createRefactoringStatusContext(superclass.getJavaElement()));
        }
        return status;
    }

    SourceActionDialog createDialog(Shell shell, IType type) throws JavaModelException {
        IVariableBinding[] fieldBindings= (IVariableBinding[]) fFields.toArray(new IVariableBinding[0]);
        IVariableBinding[] inheritedFieldBindings= (IVariableBinding[]) fInheritedFields.toArray(new IVariableBinding[0]);
        IVariableBinding[] selectedFieldBindings= (IVariableBinding[]) fSelectedFields.toArray(new IVariableBinding[0]);
        IMethodBinding[] methodBindings= (IMethodBinding[]) fMethods.toArray(new IMethodBinding[0]);
        IMethodBinding[] inheritededMethodBindings= (IMethodBinding[]) fInheritedMethods.toArray(new IMethodBinding[0]);
        return new GenerateToStringDialog(shell, fEditor, type, fieldBindings, inheritedFieldBindings, selectedFieldBindings, methodBindings, inheritededMethodBindings);
    }

    IWorkspaceRunnable createOperation(Object[] selectedBindings, CodeGenerationSettings settings, boolean regenerate, IJavaElement type, IJavaElement elementPosition) {
        return operation= GenerateToStringOperation.createOperation(fTypeBinding, selectedBindings, fUnit, elementPosition, (ToStringGenerationSettings)settings);
    }

    CodeGenerationSettings createSettings(IType type, SourceActionDialog dialog) {
        ToStringGenerationSettings settings= ((GenerateToStringDialog) dialog).getGenerationSettings();
        super.createSettings(type, dialog).setSettings(settings);
        settings.createComments= dialog.getGenerateComment();
        settings.useBlocks= useBlocks(type.getJavaProject());
        String version= fUnit.getJavaElement().getJavaProject().getOption(JavaCore.COMPILER_SOURCE, true);
        settings.is50orHigher= !JavaModelUtil.isVersionLessThan(version, JavaCore.VERSION_1_5);
        settings.is60orHigher= !JavaModelUtil.isVersionLessThan(version, JavaCore.VERSION_1_6);
        return settings;
    }

    boolean generateCandidates() throws JavaModelException {
        IVariableBinding[] candidateFields= fTypeBinding.getDeclaredFields();
        HashMap fieldsToBindings= new HashMap();
        HashMap selectedFieldsToBindings= new HashMap();
        for (int i= 0; i < candidateFields.length; i++) {
            if (!Modifier.isStatic(candidateFields[i].getModifiers())) {
                fieldsToBindings.put(candidateFields[i].getJavaElement(), candidateFields[i]);
                if (!Modifier.isTransient(candidateFields[i].getModifiers()))
                    selectedFieldsToBindings.put(candidateFields[i].getJavaElement(), candidateFields[i]);
            }
        }
        IType type= (IType)fTypeBinding.getJavaElement();
        IField[] allFields= type.getFields();
        fFields= new ArrayList();
        populateMembers(fFields, allFields, fieldsToBindings);
        fSelectedFields= new ArrayList();
        populateMembers(fSelectedFields, allFields, selectedFieldsToBindings);

        IMethodBinding[] candidateMethods= fTypeBinding.getDeclaredMethods();
        HashMap methodsToBindings= new HashMap();
        for (int i= 0; i < candidateMethods.length; i++) {
            if (!Modifier.isStatic(candidateMethods[i].getModifiers()) && candidateMethods[i].getParameterTypes().length == 0
                    && !candidateMethods[i].getReturnType().getName().equals("void") && !candidateMethods[i].getName().equals("toString") && !candidateMethods[i].getName().equals("clone")) { //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
                methodsToBindings.put(candidateMethods[i].getJavaElement(), candidateMethods[i]);
            }
        }
        fMethods= new ArrayList();
        populateMembers(fMethods, type.getMethods(), methodsToBindings);

        fInheritedFields= new ArrayList();
        fInheritedMethods= new ArrayList();
        ITypeBinding typeBinding= fTypeBinding;
        while ((typeBinding= typeBinding.getSuperclass()) != null) {
            type = (IType)typeBinding.getJavaElement();
            candidateFields= typeBinding.getDeclaredFields();
            for (int i= 0; i < candidateFields.length; i++) {
                if (!Modifier.isPrivate(candidateFields[i].getModifiers()) && !Modifier.isStatic(candidateFields[i].getModifiers()) && !contains(fFields, candidateFields[i])
                        && !contains(fInheritedFields, candidateFields[i])) {
                    fieldsToBindings.put(candidateFields[i].getJavaElement(), candidateFields[i]);
                }
            }
            populateMembers(fInheritedFields, type.getFields(), fieldsToBindings);

            candidateMethods= typeBinding.getDeclaredMethods();
            for (int i= 0; i < candidateMethods.length; i++) {
                if (!Modifier.isPrivate(candidateMethods[i].getModifiers())
                        && !Modifier.isStatic(candidateMethods[i].getModifiers())
                        && candidateMethods[i].getParameterTypes().length == 0
                        && !candidateMethods[i].getReturnType().getName().equals("void") && !contains(fMethods, candidateMethods[i]) && !contains(fInheritedMethods, candidateMethods[i]) && !candidateMethods[i].getName().equals("clone")) { //$NON-NLS-1$ //$NON-NLS-2$
                    methodsToBindings.put(candidateMethods[i].getJavaElement(), candidateMethods[i]);
                }
            }
            populateMembers(fInheritedMethods, type.getMethods(), methodsToBindings);
        }

        return true;
    }

    /**
     * Populates <code>result</code> with the bindings from <code>membersToBindings</code>, sorted
     * in the order of <code>allMembers</code>.
     * 
     * @param result list of bindings from membersToBindings, sorted in source order
     * @param allMembers all member elements in source order
     * @param membersToBindings map from {@link IMember} to {@link IBinding}
     * @since 3.6
     */
    private static void populateMembers(List result, IMember[] allMembers, HashMap membersToBindings) {
        for (int i= 0; i < allMembers.length; i++) {
            Object memberBinding= membersToBindings.remove(allMembers[i]);
            if (memberBinding != null) {
                result.add(memberBinding);
            }
        }
    }

    private static boolean contains(List inheritedFields, Object member) {
        for (Iterator iterator= inheritedFields.iterator(); iterator.hasNext();) {
            Object object= iterator.next();
            if (object instanceof IVariableBinding && member instanceof IVariableBinding)
                if (((IVariableBinding) object).getName().equals(((IVariableBinding) member).getName()))
                    return true;
            if (object instanceof IMethodBinding && member instanceof IMethodBinding)
                if (((IMethodBinding) object).getName().equals(((IMethodBinding) member).getName()))
                    return true;
        }
        return false;
    }

    String getAlreadyImplementedErrorMethodName() {
        return ActionMessages.GenerateToStringAction_tostring;
    }

    boolean isMethodAlreadyImplemented(ITypeBinding typeBinding) {
        return new ToStringInfo(typeBinding).foundToString;
    }

    String getErrorCaption() {
        return ActionMessages.GenerateToStringAction_error_caption;
    }

    String getNoMembersError() {
        //no members error never occurs
        return null;
    }

}