Object
TableColumn<V>
- Type Parameters:
V
- base type of all values in the column identified by this instance.
- All Implemented Interfaces:
CheckedContainer<V>
Identifies a column in
The constants defined in this class use a similar approach for providing serialization support.
TreeTable.Node
instances.
Each TableColumn
instance contains the column header and the type of values
for a particular column. TableColumn
s are used for fetching values from nodes
as in the following example:
public class CityLocation {
public static final ColumnTable<String> CITY_NAME = new ColumnTable<>(String.class, "City name");
public static final ColumnTable<Float> LATITUDE = new ColumnTable<>(Float.class, "Latitude");
public static final ColumnTable<Float> LONGITUDE = new ColumnTable<>(Float.class, "Longitude");
private String name;
private float latitude;
private float longitude;
CityLocation(TreeTable.Node myNode) {
name = myNode.getValue(CITY_NAME);
latitude = myNode.getValue(LATITUDE);
longitude = myNode.getValue(LONGITUDE);
}
}
Identity comparisons and serialization
This base class relies on identity comparisons instead of defining theequals(Object)
method, because the element type
is not a sufficient criterion for differentiating the columns (many columns have values
of the same type) and the header is arbitrary. Consequently
developers who create their own instances are encouraged to declare them as static final
constants as in the above example, and use those constants consistently.
This base class is not serializable because the default deserialization mechanism does not resolve automatically the deserialized instances to the above-cited singleton instances. Developers who need serialization support for their own instances have to resolve them in their own subclass. The following example is one possible way to achieve that goal:
public class CityLocation {
public static final ColumnTable<String> CITY_NAME = new Column<>("CITY_NAME", String.class, "City name");
public static final ColumnTable<Float> LATITUDE = new Column<>("LATITUDE", Float.class, "Latitude");
public static final ColumnTable<Float> LONGITUDE = new Column<>("LONGITUDE", Float.class, "Longitude");
private static final class Column<V> extends TableColumn<V> implements Serializable {
private final String field;
private Column(String field, Class<V> type, CharSequence header) {
super(type, header);
this.field = field;
}
private Object readResolve() throws ObjectStreamException {
try {
return CityLocation.class.getField(field).get(null);
} catch (Exception cause) { // Many exceptions, including unchecked ones.
throw new InvalidObjectException(cause.toString());
}
}
}
}
- Since:
- 0.3
-
Field Summary
Modifier and TypeFieldDescriptionstatic final TableColumn
<String> Frequently-used constant for a column of object identifiers.static final TableColumn
<Integer> Frequently-used constant for a column of index values.static final TableColumn
<CharSequence> Frequently-used constant for a column of object names.static final TableColumn
<CharSequence> Frequently-used constant for a column of remarks.static final TableColumn
<Class<?>> Frequently-used constant for a column of object types.static final TableColumn
<Object> Frequently-used constant for a column of object values.static final TableColumn
<Number> Frequently-used constant for a column of object numerical values.static final TableColumn
<CharSequence> Frequently-used constant for a column of object textual values. -
Constructor Summary
ModifierConstructorDescriptionprotected
Invoked on deserialization for creating an initially empty instance.TableColumn
(Class<V> type, CharSequence header) Creates a new instance for the given type of values. -
Method Summary
Modifier and TypeMethodDescriptionReturns the base type of all values in any column identified by thisTableColumn
instance.Returns the text to display as column header.Returns a string representation of this table column.
-
Field Details
-
NAME
Frequently-used constant for a column of object names. The column header is "Name" (eventually localized) and the column elements are typically instances ofString
orInternationalString
, depending on whether the data provide localization support or not. -
IDENTIFIER
-
INDEX
-
TYPE
Frequently-used constant for a column of object types. The column header is "Type" (eventually localized). -
VALUE
Frequently-used constant for a column of object values. The column header is "Value" (eventually localized) and the column elements can be instance of any kind of objects.- See Also:
-
VALUE_AS_TEXT
Frequently-used constant for a column of object textual values. The column header is "Value" (eventually localized) and the column elements are typically instances ofString
orInternationalString
, depending on whether the data provide localization support or not. -
VALUE_AS_NUMBER
Frequently-used constant for a column of object numerical values. The column header is "Value" (eventually localized). -
REMARKS
Frequently-used constant for a column of remarks. The column header is "Remarks" (eventually localized) and the column elements are typically instances ofString
orInternationalString
, depending on whether the data provide localization support or not.- Since:
- 1.0
-
-
Constructor Details
-
TableColumn
protected TableColumn()Invoked on deserialization for creating an initially empty instance. This constructor hasprotected
visibility only because the Java deserialization mechanism requires so; this constructor shall not be invoked in any other context. See the Identity comparisons and serialization section in the class javadoc for more information. -
TableColumn
Creates a new instance for the given type of values.- Parameters:
type
- base type of all values in the column identified by this instance.header
- the text to display as column header.
-
-
Method Details
-
getHeader
Returns the text to display as column header.- Returns:
- the text to display as column header.
-
getElementType
Returns the base type of all values in any column identified by thisTableColumn
instance.- Specified by:
getElementType
in interfaceCheckedContainer<V>
- Returns:
- the element type.
-
toString
Returns a string representation of this table column. The default implementation returns the header in its default locale.
-