See JSF Spec. 8.5 Table 8-1
@param value
@return boolean
497261
public static boolean isDefaultAttributeValue(Object value)
    {
        if (value == null)
        {
            return true;
        }
        else if (value instanceof Boolean)
        {
            return !((Boolean) value).booleanValue();
        }
        else if (value instanceof Number)
        {
            if (value instanceof Integer)
            {
                return ((Number) value).intValue() == Integer.MIN_VALUE;
            }
            else if (value instanceof Double)
            {
                return ((Number) value).doubleValue() == Double.MIN_VALUE;
            }
            else if (value instanceof Long)
            {
                return ((Number) value).longValue() == Long.MIN_VALUE;
            }
            else if (value instanceof Byte)
            {
                return ((Number) value).byteValue() == Byte.MIN_VALUE;
            }
            else if (value instanceof Float)
            {
                return ((Number) value).floatValue() == Float.MIN_VALUE;
            }
            else if (value instanceof Short)
            {
                return ((Number) value).shortValue() == Short.MIN_VALUE;
            }
        }
        return false;
    }
666473
public static boolean isRange(String value) {
        if (value == null) {
            return false;
        }
        try {
            Set<Integer> values = parseRange(value);
            return values.size() > 0;
        } catch (Exception e) {
            return false;
        }
    }
1126808
public boolean isValueSelectedInDropDown(final By by, final String value) {
		WebElement element = driver.findElement(by);

		StringBuilder builder = new StringBuilder(".//option[@value = ");
		builder.append(escapeQuotes(value));
		builder.append("]");
		List<WebElement> options = element.findElements(By.xpath(builder
				.toString()));

		for (WebElement opt : options) {
			if (opt.isSelected()) {
				return true;
			}
		}

		return false;
	}
1110141
private static boolean isValueAValidGeoQuery(final Object value) {
        if (value instanceof DBObject) {
            String key = ((DBObject) value).keySet().iterator().next();
            return key.equals("$box") || key.equals("$center") || key.equals("$centerSphere") || key.equals("$polygon");
        }
        return false;
    }
1163425
public boolean hasValueEnabled(String value) {
        for (OptionGroup group : optionGroups.values()) {
            if (group.hasValueEnabled(value)) {
                return true;
            }
        }

        return false;
    }
516988
@NullSafe
  public static boolean isWhole(Number value) {
    return (value instanceof Byte || value instanceof Short || value instanceof Integer || value instanceof Long
      || value instanceof BigInteger);
  }
454073
public boolean containsValue(Object value) {
        if (value == null) {
            value = new Null();
        }

        Entry tab[] = mTable;
        
        for (int i = tab.length ; i-- > 0 ;) {
            for (Entry e = tab[i], prev = null; e != null; e = e.mNext) {
                Object entryValue = e.getValue();

                if (entryValue == null) {
                    // Clean up after a cleared Reference.
                    mModCount++;
                    if (prev != null) {
                        prev.mNext = e.mNext;
                    }
                    else {
                        tab[i] = e.mNext;
                    }
                    mCount--;
                }
                else if (value.equals(entryValue)) {
                    return true;
                }
                else {
                    prev = e;
                }
            }
        }

        return false;
    }
789733
private boolean isTrue(final Object value) {

		if (value != null) {

			if (value instanceof Boolean) {

				return (Boolean)value;
			}

			if (value instanceof String) {

				return Boolean.valueOf((String)value);
			}

			// not sure if good..
			if (value instanceof Number) {

				return ((Number)value).longValue() > 0;
			}
		}

		return false;
	}
1224223
@JSFProperty(defaultValue = "false", tagExcluded = true)
    public boolean isLocalValueSet()
    {
        Object value = getStateHelper().get(PropertyKeys.localValueSet);
        if (value != null)
        {
            return (Boolean) value;        
        }
        return false;
    }
886835
private boolean checkForMapValue(TabularType pType) {
        CompositeType rowType = pType.getRowType();
        // Two entries in the row: "key" and "value"
        return rowType.containsKey(TD_KEY_VALUE) && rowType.containsKey(TD_KEY_KEY) && rowType.keySet().size() == 2;
    }
103840
public boolean containsValue(Object value) {
        Entry tab[] = mTable;
        
        if (value == null) {
            for (int i = tab.length ; i-- > 0 ;) {
                for (Entry e = tab[i], prev = null; e != null; e = e.mNext) {
                    if (e.getKey() == null) {
                        // Clean up after a cleared Reference.
                        mModCount++;
                        if (prev != null) {
                            prev.mNext = e.mNext;
                        }
                        else {
                            tab[i] = e.mNext;
                        }
                        mCount--;
                    }
                    else if (e.mValue == null) {
                        return true;
                    }
                    else {
                        prev = e;
                    }
                }
            }
        }
        else {
            for (int i = tab.length ; i-- > 0 ;) {
                for (Entry e = tab[i], prev = null; e != null; e = e.mNext) {
                    if (e.getKey() == null) {
                        // Clean up after a cleared Reference.
                        mModCount++;
                        if (prev != null) {
                            prev.mNext = e.mNext;
                        }
                        else {
                            tab[i] = e.mNext;
                        }
                        mCount--;
                    }
                    else if (value.equals(e.mValue)) {
                        return true;
                    }
                    else {
                        prev = e;
                    }
                }
            }
        }

        return false;
    }
1226597
public static final boolean isValid(final String value) {
        if (value == null) {
            return true;
        }
        if ((value.length() < 3) || (value.length() > 20)) {
            return false;
        }
        return PATTERN.matcher(value.toString()).matches();
    }
774002
@Override
    public boolean containsValue(Object value) {
        for (V v : values()) {
            if (v.equals(value)) {
                return true;
            }
        }
        return false;
    }
263884
public boolean acceptsValue(String value) {
		if (value==null) {
			return false;
		} else if (hasValues()) {
			return getValuesList().contains(value);
		} else {
			return true;
		}
	}
706745
public static boolean isValidJsonValue( Object value ) {
      if( JSONNull.getInstance()
            .equals( value ) || value instanceof JSON || value instanceof Boolean
            || value instanceof Byte || value instanceof Short
            || value instanceof Integer || value instanceof Long || value instanceof Double
            || value instanceof BigInteger || value instanceof BigDecimal
            || value instanceof JSONFunction || value instanceof JSONString
            || value instanceof String ){
         return true;
      }
      return false;
   }
83644
public static final boolean isValid(final String value) {
        if (value == null) {
            return true;
        }
        final Locale locale;
        final int p = value.indexOf("__");
        if (p > -1) {
            locale = new Locale(value.substring(0, p), null, value.substring(p + 2));
        } else {
            final StringTokenizer tok = new StringTokenizer(value, "_");
            if (tok.countTokens() == 1) {
                locale = new Locale(value);
            } else if (tok.countTokens() == 2) {
                locale = new Locale(tok.nextToken(), tok.nextToken());
            } else if (tok.countTokens() == 3) {
                locale = new Locale(tok.nextToken(), tok.nextToken(), tok.nextToken());
            } else {
                return false;
            }
        }
        return LocaleConverter.validLocale(locale);
    }
950210
public function isValueValid($value) {
		return $value instanceof DataType\BooleanType || $value instanceof DataType\NumberType || $value instanceof Type\StructuredValueType || $value instanceof DataType\TextType;
	}