org.eclipse.linuxtools.statesystem.core/src/org/eclipse/linuxtools/statesystem/core/statevalue/NullStateValue.java

   1 /*******************************************************************************
   2  * Copyright (c) 2012, 2013 Ericsson
   3  * Copyright (c) 2010, 2011 École Polytechnique de Montréal
   4  * Copyright (c) 2010, 2011 Alexandre Montplaisir <alexandre.montplaisir@gmail.com>
   5  *
   6  * All rights reserved. This program and the accompanying materials are
   7  * made available under the terms of the Eclipse Public License v1.0 which
   8  * accompanies this distribution, and is available at
   9  * http://www.eclipse.org/legal/epl-v10.html
  10  *
  11  *******************************************************************************/
  12
  13 package org.eclipse.linuxtools.statesystem.core.statevalue;
  14
  15 import org.eclipse.jdt.annotation.Nullable;
  16
  17 /**
  18  * A state value that contains no particular value. It is sometimes needed over
  19  * a "null" reference, since we avoid NPE's this way.
  20  *
  21  * It can also be read either as a String ("nullValue") or an Integer (-1).
  22  *
  23  * @version 1.0
  24  * @author Alexandre Montplaisir
  25  */
  26 final class NullStateValue extends TmfStateValue {
  27
  28     private final String value = "nullValue"; //$NON-NLS-1$
  29
  30     @Override
  31     public Type getType() {
  32         return Type.NULL;
  33     }
  34
  35     @Override
  36     public boolean isNull() {
  37         return true;
  38     }
  39
  40     @Override
  41     public boolean equals(@Nullable Object object) {
  42         return (object instanceof NullStateValue);
  43     }
  44
  45     @Override
  46     public int hashCode() {
  47        return 0;
  48     }
  49
  50     @Override
  51     public String toString() {
  52         return value;
  53     }
  54
  55     // ------------------------------------------------------------------------
  56     // Unboxing methods. Null values can be unboxed into any type.
  57     // ------------------------------------------------------------------------
  58
  59     @Override
  60     public int unboxInt() {
  61         return -1;
  62     }
  63
  64     @Override
  65     public long unboxLong() {
  66         return -1;
  67     }
  68
  69     @Override
  70     public double unboxDouble() {
  71         return Double.NaN;
  72     }
  73
  74     @Override
  75     public String unboxStr() {
  76         return value;
  77     }
  78 }