1 /*
   2  * Copyright (c) 2009, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.nio.fs;
  27 
  28 import java.util.*;
  29 import java.nio.file.*;
  30 import java.nio.charset.Charset;
  31 import sun.security.action.GetPropertyAction;
  32 
  33 /**
  34  * Utility methods
  35  */
  36 
  37 class Util {
  38     private Util() { }
  39 
  40     private static final Charset jnuEncoding = Charset.forName(
  41         GetPropertyAction.privilegedGetProperty("sun.jnu.encoding"));
  42 
  43     /**
  44      * Returns {@code Charset} corresponding to the sun.jnu.encoding property
  45      */
  46     static Charset jnuEncoding() {
  47         return jnuEncoding;
  48     }
  49 
  50     /**
  51      * Encodes the given String into a sequence of bytes using the {@code Charset}
  52      * specified by the sun.jnu.encoding property.
  53      */
  54     static byte[] toBytes(String s) {
  55         return s.getBytes(jnuEncoding);
  56     }
  57 
  58     /**
  59      * Constructs a new String by decoding the specified array of bytes using the
  60      * {@code Charset} specified by the sun.jnu.encoding property.
  61      */
  62     static String toString(byte[] bytes) {
  63         return new String(bytes, jnuEncoding);
  64     }
  65 
  66 
  67     /**
  68      * Splits a string around the given character. The array returned by this
  69      * method contains each substring that is terminated by the character. Use
  70      * for simple string splitting cases when needing to avoid loading regex.
  71      */
  72     static String[] split(String s, char c) {
  73         int count = 0;
  74         for (int i=0; i<s.length(); i++) {
  75             if (s.charAt(i) == c)
  76                 count++;
  77         }
  78         String[] result = new String[count+1];
  79         int n = 0;
  80         int last = 0;
  81         for (int i=0; i<s.length(); i++) {
  82             if (s.charAt(i) == c) {
  83                 result[n++] = s.substring(last, i);
  84                 last = i + 1;
  85             }
  86         }
  87         result[n] = s.substring(last, s.length());
  88         return result;
  89     }
  90 
  91     /**
  92      * Returns a Set containing the given elements.
  93      */
  94     @SafeVarargs
  95     static <E> Set<E> newSet(E... elements) {
  96         HashSet<E> set = new HashSet<>();
  97         for (E e: elements) {
  98             set.add(e);
  99         }
 100         return set;
 101     }
 102 
 103     /**
 104      * Returns a Set containing all the elements of the given Set plus
 105      * the given elements.
 106      */
 107     @SafeVarargs
 108     static <E> Set<E> newSet(Set<E> other, E... elements) {
 109         HashSet<E> set = new HashSet<>(other);
 110         for (E e: elements) {
 111             set.add(e);
 112         }
 113         return set;
 114     }
 115 
 116     /**
 117      * Returns {@code true} if symbolic links should be followed
 118      */
 119     static boolean followLinks(LinkOption... options) {
 120         boolean followLinks = true;
 121         for (LinkOption option: options) {
 122             if (option == LinkOption.NOFOLLOW_LINKS) {
 123                 followLinks = false;
 124             } else if (option == null) {
 125                 throw new NullPointerException();
 126             } else {
 127                 throw new AssertionError("Should not get here");
 128             }
 129         }
 130         return followLinks;
 131     }
 132 }