Java File Touch touch(File file)

Description

Implements the same behaviour as the "touch" utility on Unix.

License

Apache License

Parameter

Parameter	Description
file	the File to touch

Exception

Parameter	Description
IOException	If an I/O problem occurs

Declaration

static void touch(File file) throws IOException 

Method Source Code

//package com.java2s;
/**/*  w  w w.jav  a  2 s . c  o  m*/
 * Licensed to Jasig under one or more contributor license
 * agreements. See the NOTICE file distributed with this work
 * for additional information regarding copyright ownership.
 * Jasig 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.
 */

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Main {
    /**
     * Implements the same behaviour as the "touch" utility on Unix. It creates
     * a new file with size 0 or, if the file exists already, it is opened and
     * closed without modifying it, but updating the file date and time.
     * <p>
     * NOTE: As from v1.3, this method throws an IOException if the last
     * modified date of the file cannot be set. Also, as from v1.3 this method
     * creates parent directories if they do not exist.
     *
     * @param file  the File to touch
     * @throws IOException If an I/O problem occurs
     */
    static void touch(File file) throws IOException {
        if (!file.exists()) {
            OutputStream out = openOutputStream(file);
            closeQuietly(out);
        }
        boolean success = file.setLastModified(System.currentTimeMillis());
        if (!success) {
            throw new IOException("Unable to set the last modification time for " + file);
        }
    }

    /**
      * Opens a {@link FileOutputStream} for the specified file, checking and
      * creating the parent directory if it does not exist.
      * <p>
      * At the end of the method either the stream will be successfully opened,
      * or an exception will have been thrown.
      * <p>
      * The parent directory will be created if it does not exist.
      * The file will be created if it does not exist.
      * An exception is thrown if the file object exists but is a directory.
      * An exception is thrown if the file exists but cannot be written to.
      * An exception is thrown if the parent directory cannot be created.
      * 
      * @param file  the file to open for output, must not be <code>null</code>
      * @return a new {@link FileOutputStream} for the specified file
      * @throws IOException if the file object is a directory
      * @throws IOException if the file cannot be written to
      * @throws IOException if a parent directory needs creating but that fails
      * @since Commons IO 1.3
      */
    static FileOutputStream openOutputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canWrite() == false) {
                throw new IOException("File '" + file + "' cannot be written to");
            }
        } else {
            File parent = file.getParentFile();
            if (parent != null && parent.exists() == false) {
                if (parent.mkdirs() == false) {
                    throw new IOException("File '" + file + "' could not be created");
                }
            }
        }
        return new FileOutputStream(file);
    }

    /**
     * Unconditionally close an <code>OutputStream</code>.
     * <p>
     * Equivalent to {@link OutputStream#close()}, except any exceptions will be ignored.
     * This is typically used in finally blocks.
     *
     * @param output  the OutputStream to close, may be null or already closed
     */
    static void closeQuietly(OutputStream output) {
        try {
            if (output != null) {
                output.close();
            }
        } catch (IOException ioe) {
            // ignore
        }
    }

    /**
      * Unconditionally close an <code>InputStream</code>.
      * <p>
      * Equivalent to {@link InputStream#close()}, except any exceptions will be ignored.
      * This is typically used in finally blocks.
      *
      * @param input  the InputStream to close, may be null or already closed
      */
    static void closeQuietly(InputStream input) {
        try {
            if (input != null) {
                input.close();
            }
        } catch (IOException ioe) {
            // ignore
        }
    }
}

Related

1. touch(File f)
2. touch(File file)
3. touch(File file)
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8. touch(File file)
9. touch(File file)