commons-vfs2/src/main/java/org/apache/commons/vfs2/filter/NotFileFilter.java

/*
 * 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.commons.vfs2.filter;

import java.io.Serializable;

import org.apache.commons.vfs2.FileFilter;
import org.apache.commons.vfs2.FileSelectInfo;
import org.apache.commons.vfs2.FileSystemException;

/**
 * This filter produces a logical NOT of the filters specified.
 *
 * @author This code was originally ported from Apache Commons IO File Filter
 * @see "http://commons.apache.org/proper/commons-io/"
 * @since 2.4
 */
public class NotFileFilter implements FileFilter, Serializable {

    private static final long serialVersionUID = 1L;

    /** The filter. */
    private final FileFilter filter;

    /**
     * Constructs a new file filter that NOTs the result of another filter.
     *
     * @param filter the filter, must not be null
     */
    public NotFileFilter(final FileFilter filter) {
        if (filter == null) {
            throw new IllegalArgumentException("The filter must not be null");
        }
        this.filter = filter;
    }

    /**
     * Returns the logical NOT of the underlying filter's return value for the same
     * File.
     *
     * @param fileSelectInfo the File to check
     *
     * @return {@code true} if the filter returns {@code false}
     * @throws FileSystemException Thrown for file system errors.
     */
    @Override
    public boolean accept(final FileSelectInfo fileSelectInfo) throws FileSystemException {
        return !filter.accept(fileSelectInfo);
    }

    /**
     * Provide a String representation of this file filter.
     *
     * @return a String representation
     */
    @Override
    public String toString() {
        return super.toString() + "(" + filter.toString() + ")";
    }

}