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Ant example source code file (BaseSelector.java)

This example Ant source code file (BaseSelector.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Ant tags/keywords

baseselector, baseselector, buildexception, buildexception, datatype, file, file, fileselector, io, string, string

The BaseSelector.java source code

/*
 *  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.tools.ant.types.selectors;

import java.io.File;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.types.DataType;

/**
 * A convenience base class that you can subclass Selectors from. It
 * provides some helpful common behaviour. Note that there is no need
 * for Selectors to inherit from this class, it is only necessary that
 * they implement FileSelector.
 *
 * @since 1.5
 */
public abstract class BaseSelector extends DataType implements FileSelector {

    private String errmsg = null;


    /**
     * Do nothing constructor.
     */
    public BaseSelector() {
    }

    /**
     * Allows all selectors to indicate a setup error. Note that only
     * the first error message is recorded.
     *
     * @param msg The error message any BuildException should throw.
     */
    public void setError(String msg) {
        if (errmsg == null) {
            errmsg = msg;
        }
    }

    /**
     * Returns any error messages that have been set.
     *
     * @return the error condition
     */
    public String getError() {
        return errmsg;
    }


    /**
     * <p>Subclasses can override this method to provide checking of their
     * state. So long as they call validate() from isSelected(), this will
     * be called automatically (unless they override validate()).</p>
     * <p>Implementations should check for incorrect settings and call
     * setError() as necessary.</p>
     */
    public void verifySettings() {
        if (isReference()) {
            ((BaseSelector) getCheckedRef()).verifySettings();
        }
    }


    /**
     * Subclasses can use this to throw the requisite exception
     * in isSelected() in the case of an error condition.
     */
    public void validate() {
        if (getError() == null) {
            verifySettings();
        }
        if (getError() != null) {
            throw new BuildException(errmsg);
        }
    }

    /**
     * Method that each selector will implement to create their
     * selection behaviour. If there is a problem with the setup
     * of a selector, it can throw a BuildException to indicate
     * the problem.
     *
     * @param basedir A java.io.File object for the base directory
     * @param filename The name of the file to check
     * @param file A File object for this filename
     * @return whether the file should be selected or not
     */
    public abstract boolean isSelected(File basedir, String filename,
                                       File file);

}


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