Convert


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.core.internal.utils;
12  
13  import java.io.UnsupportedEncodingException  ;
14  
15  public class Convert {
16  
17      /**
18       * Converts the string argument to a byte array.
19       */
20      public static String   fromUTF8(byte[] b) {
21          String   result;
22          try {
23              result = new String  (b, "UTF8"); //$NON-NLS-1$
24          } catch (UnsupportedEncodingException   e) {
25              result = new String  (b);
26          }
27          return result;
28      }
29  
30      /**
31       * Converts the string argument to a byte array.
32       */
33      public static byte[] toUTF8(String   s) {
34          byte[] result;
35          try {
36              result = s.getBytes("UTF8"); //$NON-NLS-1$
37          } catch (UnsupportedEncodingException   e) {
38              result = s.getBytes();
39          }
40          return result;
41      }
42  
43      /**
44       * Performs conversion of a long value to a byte array representation.
45       *
46       * @see #bytesToLong(byte[])
47       */
48      public static byte[] longToBytes(long value) {
49  
50          // A long value is 8 bytes in length.
51          byte[] bytes = new byte[8];
52  
53          // Convert and copy value to byte array:
54          //   -- Cast long to a byte to retrieve least significant byte;
55          //   -- Left shift long value by 8 bits to isolate next byte to be converted;
56          //   -- Repeat until all 8 bytes are converted (long = 64 bits).
57          // Note: In the byte array, the least significant byte of the long is held in
58          // the highest indexed array bucket.
59  
60          for (int i = 0; i < bytes.length; i++) {
61              bytes[(bytes.length - 1) - i] = (byte) value;
62              value >>>= 8;
63          }
64  
65          return bytes;
66      }
67  
68      /**
69       * Performs conversion of a byte array to a long representation.
70       *
71       * @see #longToBytes(long)
72       */
73      public static long bytesToLong(byte[] value) {
74  
75          long longValue = 0L;
76  
77          // See method convertLongToBytes(long) for algorithm details.   
78          for (int i = 0; i < value.length; i++) {
79              // Left shift has no effect thru first iteration of loop.
80              longValue <<= 8;
81              longValue ^= value[i] & 0xFF;
82          }
83  
84          return longValue;
85      }
86  }
87
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