Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.wicket.extensions.wizard; import java.util.ArrayDeque; import java.util.ArrayList; import java.util.Collections; import java.util.Iterator; import java.util.List; import org.apache.wicket.util.io.IClusterable; /** * Default implementation of {@link IWizardModel}, which models a semi-static wizard. This means * that all steps should be known upfront, and added to the model on construction. Steps can be * optional by using {@link ICondition}. The wizard is initialized with a wizard model through * calling method {@link Wizard#init(IWizardModel)}. * <p> * Steps can be added to this model directly using either the {@link #add(IWizardStep) normal add * method} or {@link #add(IWizardStep, ICondition) the conditional add method}. * </p> * * <p> * <a href="https://wizard-framework.dev.java.net/">Swing Wizard Framework</a> served as a valuable * source of inspiration. * </p> * * @author Eelco Hillenius */ public class WizardModel extends AbstractWizardModel { /** * Interface for conditional displaying of wizard steps. */ @FunctionalInterface public interface ICondition extends IClusterable { /** * Evaluates the current state and returns whether the step that is coupled to this * condition is available. * * @return True if the step this condition is coupled to is available, false otherwise */ public boolean evaluate(); } /** * Condition that always evaluates true. */ public static final ICondition TRUE = (() -> true); private static final long serialVersionUID = 1L; /** The currently active step. */ private IWizardStep activeStep; /** Conditions with steps. */ private final List<ICondition> conditions = new ArrayList<>(); /** State history. */ private final ArrayDeque<IWizardStep> history = new ArrayDeque<>(); /** The wizard steps. */ private final List<IWizardStep> steps = new ArrayList<>(); /** * Construct. */ public WizardModel() { } /** * Adds the next step to the wizard. If the {@link WizardStep} implements {@link ICondition}, * then this method is equivalent to calling {@link #add(IWizardStep, ICondition) add(step, * (ICondition)step)}. * * @param step * the step to added. */ public void add(final IWizardStep step) { if (step instanceof ICondition) { add(step, (ICondition) step); } else { add(step, TRUE); } } /** * Adds an optional step to the model. The step will only be displayed if the specified * condition is met. * * @param step * The step to add * @param condition * the {@link ICondition} under which it should be included in the wizard. */ public void add(final IWizardStep step, final ICondition condition) { steps.add(step); conditions.add(condition); } /** * Gets the current active step the wizard should display. * * @return the active step. */ @Override public final IWizardStep getActiveStep() { return activeStep; } /** * Checks if the last button should be enabled. * * @return <tt>true</tt> if the last button should be enabled, <tt>false</tt> otherwise. * @see IWizardModel#isLastVisible */ @Override public boolean isLastAvailable() { return allStepsComplete() && !isLastStep(activeStep); } /** * @see org.apache.wicket.extensions.wizard.IWizardModel#isLastStep(org.apache.wicket.extensions.wizard.IWizardStep) */ @Override public boolean isLastStep(final IWizardStep step) { return findLastStep().equals(step); } /** * Checks if the next button should be enabled. * * @return <tt>true</tt> if the next button should be enabled, <tt>false</tt> otherwise. */ @Override public boolean isNextAvailable() { return activeStep.isComplete() && !isLastStep(activeStep); } /** * Checks if the previous button should be enabled. * * @return <tt>true</tt> if the previous button should be enabled, <tt>false</tt> otherwise. */ @Override public boolean isPreviousAvailable() { return !history.isEmpty(); } /** * @see org.apache.wicket.extensions.wizard.IWizardModel#last() */ @Override public void last() { history.push(getActiveStep()); IWizardStep lastStep = findLastStep(); setActiveStep(lastStep); } /** * @see org.apache.wicket.extensions.wizard.IWizardModel#next() */ @Override public void next() { history.push(getActiveStep()); IWizardStep step = findNextVisibleStep(); setActiveStep(step); } /** * @see org.apache.wicket.extensions.wizard.IWizardModel#previous() */ @Override public void previous() { IWizardStep step = history.pop(); setActiveStep(step); } /** * @see org.apache.wicket.extensions.wizard.IWizardModel#reset() */ @Override public void reset() { history.clear(); activeStep = null; for (IWizardStep step : steps) { step.init(this); } setActiveStep(findNextVisibleStep()); } /** * Sets the active step. * * @param step * the new active step step. */ public void setActiveStep(final IWizardStep step) { if ((activeStep != null) && (step != null) && activeStep.equals(step)) { return; } activeStep = step; fireActiveStepChanged(step); } /** * @see IWizardModel#stepIterator() */ @Override public Iterator<IWizardStep> stepIterator() { List<IWizardStep> filtered = new ArrayList<>(); for (int s = 0; s < steps.size(); s++) { if (conditions.get(s).evaluate()) { filtered.add(steps.get(s)); } } return filtered.iterator(); } /** * Returns true if all the steps in the wizard return <tt>true</tt> from * {@link IWizardStep#isComplete}. This is primarily used to determine if the last button can be * enabled. * * @return <tt>true</tt> if all the steps in the wizard are complete, <tt>false</tt> otherwise. */ protected final boolean allStepsComplete() { for (IWizardStep step : steps) { if (!step.isComplete()) { return false; } } return true; } /** * Finds the last step in this model. * * @return The last step */ protected final IWizardStep findLastStep() { for (int i = conditions.size() - 1; i >= 0; i--) { ICondition condition = conditions.get(i); if (condition.evaluate()) { return steps.get(i); } } throw new IllegalStateException("Wizard contains no visible steps"); } /** * Finds the next visible step based on the active step. * * @return The next visible step based on the active step */ protected final IWizardStep findNextVisibleStep() { int startIndex = (activeStep == null) ? 0 : steps.indexOf(activeStep) + 1; for (int i = startIndex; i < conditions.size(); i++) { ICondition condition = conditions.get(i); if (condition.evaluate()) { return steps.get(i); } } throw new IllegalStateException("Wizard contains no more visible steps"); } /** * Gets conditions. * * @return unmodifiable list of conditions */ public List<ICondition> getConditions() { return Collections.unmodifiableList(conditions); } }