Android Path Relative Get getPathRelativeTo(File fileChild, File fileRoot)

Description

Returns that portion of the path of fileChild which is relative to the path of fileRoot.

License

Open Source License

Exception

Parameter	Description
IllegalArgumentException	if fileChild is null; fileRoot is null; fileChild is not contained under fileRoot

Declaration

public static String getPathRelativeTo(File fileChild, File fileRoot)
        throws IllegalArgumentException 

Method Source Code

/*/*from  w ww .j av  a2 s. co m*/
Copyright ? 2008 Brent Boyer

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser 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 Lesser GNU General Public License for more details.

You should have received a copy of the Lesser GNU General Public License along with this program (see the license directory in this project).  If not, see <http://www.gnu.org/licenses/>.
 */

import bb.science.FormatUtil;
import bb.util.Check;
import bb.util.StringUtil;
import bb.util.ThrowableUtil;
import bb.util.logging.LogUtil;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.util.Random;
import java.util.logging.Level;
import org.junit.Assert;
import org.junit.Test;

public class Main{
    /**
     * Returns that portion of the path of fileChild which is relative to the path of fileRoot.
     * For example, if fileChild.getPath() = "/dirA/dirB/dirC/file1" and fileRoot.getPath() = "/dirA/dirB"
     * then the result is "dirC/file1".
     * Note that the result never begins with a path separator char.
     * Neither File need actually exist; this method simply does String operations on their paths.
     * If fileChild equals fileRoot, then a blank String is returned.
     * <p>
     * @throws IllegalArgumentException if fileChild is null; fileRoot is null; fileChild is not contained under fileRoot
     */
    public static String getPathRelativeTo(File fileChild, File fileRoot)
            throws IllegalArgumentException {
        Check.arg().notNull(fileChild);
        Check.arg().notNull(fileRoot);
        if (fileChild.equals(fileRoot))
            return "";

        String pathChild = fileChild.getPath();
        String pathRoot = fileRoot.getPath();
        if (!pathChild.startsWith(pathRoot))
            throw new IllegalArgumentException("fileChild = " + pathChild
                    + " is not contained under fileRoot = " + pathRoot);

        int skipDirChar = pathRoot.endsWith(File.separator) ? 0 : 1; // handles the directory separator char being present or absent
        int indexChild = pathRoot.length() + skipDirChar;
        return pathChild.substring(indexChild);
    }
}

Related

1. convertToRelativePath(String absolutePath, String relativeTo)
2. getRelativeFileName(File file, File basedir)
3. getRelativePath(File parent, File file)
4. getWindowsRelativePath(String basedir, String path)
5. relativePathFromBase(File file, File basedir)