Java tutorial
/* * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* * WekaNewInstance.java * Copyright (C) 2011-2019 University of Waikato, Hamilton, New Zealand */ package adams.flow.transformer; import adams.core.QuickInfoHelper; import adams.core.base.BaseClassname; import adams.flow.core.Token; import weka.core.DenseInstance; import weka.core.Instance; import weka.core.Instances; import java.lang.reflect.Constructor; /** <!-- globalinfo-start --> * Creates a new weka.core.Instance-derived object, with all values marked as missing.<br> * The class implementing the weka.core.Instance interface needs to have a constructor that takes the number of attributes as sole parameter. * <br><br> <!-- globalinfo-end --> * <!-- flow-summary-start --> * Input/output:<br> * - accepts:<br> * weka.core.Instances<br> * - generates:<br> * weka.core.Instance<br> * <br><br> <!-- flow-summary-end --> * <!-- options-start --> * Valid options are: <br><br> * * <pre>-D <int> (property: debugLevel) * The greater the number the more additional info the scheme may output to * the console (0 = off). * default: 0 * minimum: 0 * </pre> * * <pre>-name <java.lang.String> (property: name) * The name of the actor. * default: WekaNewInstance * </pre> * * <pre>-annotation <adams.core.base.BaseText> (property: annotations) * The annotations to attach to this actor. * default: * </pre> * * <pre>-skip (property: skip) * If set to true, transformation is skipped and the input token is just forwarded * as it is. * </pre> * * <pre>-stop-flow-on-error (property: stopFlowOnError) * If set to true, the flow gets stopped in case this actor encounters an error; * useful for critical actors. * </pre> * * <pre>-instance-class <adams.core.base.BaseClassname> (property: instanceClass) * The full class name of the weka.core.Instance-derived object to instantiate. * default: weka.core.DenseInstance * </pre> * <!-- options-end --> * * @author fracpete (fracpete at waikato dot ac dot nz) */ public class WekaNewInstance extends AbstractTransformer { /** for serialization. */ private static final long serialVersionUID = -786486914801535807L; /** the class of instance to create. */ protected BaseClassname m_InstanceClass; /** * Returns a string describing the object. * * @return a description suitable for displaying in the gui */ @Override public String globalInfo() { return "Creates a new weka.core.Instance-derived object, with all values " + "marked as missing.\n" + "The class implementing the weka.core.Instance interface needs to " + "have a constructor that takes the number of attributes as sole " + "parameter."; } /** * Adds options to the internal list of options. */ @Override public void defineOptions() { super.defineOptions(); m_OptionManager.add("instance-class", "instanceClass", new BaseClassname(DenseInstance.class)); } /** * Sets the class name of the Instance object to create. * * @param value the class */ public void setInstanceClass(BaseClassname value) { m_InstanceClass = value; reset(); } /** * Returns the class name of the Instance object to create. * * @return the class */ public BaseClassname getInstanceClass() { return m_InstanceClass; } /** * Returns the tip text for this property. * * @return tip text for this property suitable for * displaying in the GUI or for listing the options. */ public String instanceClassTipText() { return "The full class name of the weka.core.Instance-derived object to instantiate."; } /** * Returns a quick info about the actor, which will be displayed in the GUI. * * @return null if no info available, otherwise short string */ @Override public String getQuickInfo() { return QuickInfoHelper.toString(this, "instanceClass", m_InstanceClass); } /** * Returns the class that the consumer accepts. * * @return <!-- flow-accepts-start -->weka.core.Instances.class<!-- flow-accepts-end --> */ public Class[] accepts() { return new Class[] { Instances.class }; } /** * Returns the class of objects that it generates. * * @return <!-- flow-generates-start -->weka.core.Instance.class<!-- flow-generates-end --> */ public Class[] generates() { return new Class[] { Instance.class }; } /** * Executes the flow item. * * @return null if everything is fine, otherwise error message */ @Override protected String doExecute() { String result; Instances data; Instance inst; Class cls; Constructor constr; result = null; data = (Instances) m_InputToken.getPayload(); try { cls = m_InstanceClass.classValue(); constr = cls.getConstructor(new Class[] { Integer.TYPE }); inst = (Instance) constr.newInstance(new Object[] { data.numAttributes() }); inst.setDataset(data); m_OutputToken = new Token(inst); } catch (Exception e) { result = handleException("Failed to create new instance: ", e); } return result; } }