Class LayoutMap

java.lang.Object
com.jgoodies.forms.layout.LayoutMap
public final class LayoutMap extends Object
Provides a hierarchical variable expansion useful to improve layout consistency, style guide compliance, and layout readability.

A LayoutMap maps variable names to layout expression Strings. The FormLayout, ColumnSpec, and RowSpec parsers expand variables before an encoded layout specification is parsed and converted into ColumnSpec and RowSpec values. Variables start with the '$' character. The variable name can be wrapped by braces ('{' and '}'). For example, you can write: new FormLayout("pref, $lcg, pref",) or new FormLayout("pref, ${lcg}, pref").

LayoutMaps build a chain; each LayoutMap has an optional parent map. The root is defined by getRoot(). Application-wide variables should be defined in the root LayoutMap. If you want to override application-wide variables locally, obtain a LayoutMap using new LayoutMap(), configure it, and provide it as argument to the FormLayout, ColumnSpec, and RowSpec constructors/factory methods.

By default the root LayoutMap provides the following associations:

Variable NameAbbreviationsOrientationDescription
label-component-gaplcg, lcgaphorizontalgap between a label and its component
buttonbhorizontalbutton column with minimum width
related-gaprg, rgapbothgap between two related components
unrelated-gapug, ugapbothgap between two unrelated components
line-gaplg, lgapverticalgap between two lines
narrow-line-gapnlg, nlgapverticalnarrow gap between two lines
paragraphpg, pgapverticalgap between two paragraphs/sections

Examples: 

// Predefined variables
new FormLayout(
    "pref, $lcgap, pref, $rgap, pref",
    "p, $lgap, p, $lgap, p");

// Custom variables
LayoutMap.getRoot().columnPut("half", "39dlu");
LayoutMap.getRoot().columnPut("full", "80dlu");
LayoutMap.getRoot().rowPut("table", "fill:0:grow");
LayoutMap.getRoot().rowPut("table50", "fill:50dlu:grow");
new FormLayout(
    "pref, $lcgap, $half, 2dlu, $half",
    "p, $lcgap, $table50");
new FormLayout(
    "pref, $lcgap, $full",
    "p, $lcgap, $table50");

// Nested variables
LayoutMap.getRoot().columnPut("c-gap-c", "$half, 2dlu, $half");
new FormLayout(
    "pref, $lcgap, ${c-gap-c}", // -> "pref, $lcgap, $half, 2dlu, $half",
    "p, $lcgap, $table");
LayoutMap holds two internal Maps that associate key Strings with expression Strings for the columns and rows respectively. Null values are not allowed.

Tips:

  • You should carefully override predefined variables, because variable users may expect that these don't change.
  • Set custom variables in the root LayoutMap.
  • Avoid aliases for custom variables.
Since:
1.2
Version:
$Revision: 1.18 $
Author:
Karsten Lentzsch
See Also:

  • Constructor Details

    • LayoutMap

      public LayoutMap()
      Constructs a LayoutMap that has the root LayoutMap as parent.

    • LayoutMap

      public LayoutMap(LayoutMap parent)
      Constructs a LayoutMap with the given optional parent.
      Parameters:
      parent - the parent LayoutMap, may be null

  • Method Details

    • getRoot

      public static LayoutMap getRoot()
      Lazily initializes and returns the LayoutMap that is used for variable expansion, if no custom LayoutMap is provided.
      Returns:
      the LayoutMap that is used, if no custom LayoutMap is provided

    • columnContainsKey

      public boolean columnContainsKey(String key)
      Returns true if this map or a parent map - if any - contains a mapping for the specified key.
      Parameters:
      key - key whose presence in this LayoutMap chain is to be tested.
      Returns:
      true if this map contains a column mapping for the specified key.
      Throws:
      NullPointerException - if the key is null.
      See Also:

    • columnGet

      public String columnGet(String key)
      Looks up and returns the String associated with the given key. First looks for an association in this LayoutMap. If there's no association, the lookup continues with the parent map - if any.
      Parameters:
      key - key whose associated value is to be returned.
      Returns:
      the column String associated with the key, or null if no LayoutMap in the parent chain contains an association.
      Throws:
      NullPointerException - if key is null
      See Also:

    • columnPut

      public String columnPut(String key, String value)
      Associates the specified column String with the specified key in this map. If the map previously contained a mapping for this key, the old value is replaced by the specified value. The value set in this map overrides an association - if any - in the chain of parent LayoutMaps.

      The value must not be null. To remove an association from this map use columnRemove(String).

      Parameters:
      key - key with which the specified value is to be associated.
      value - column expression value to be associated with the specified key.
      Returns:
      previous String associated with specified key, or null if there was no mapping for key.
      Throws:
      NullPointerException - if the key or value is null.
      See Also:

    • columnPut

      public String columnPut(String key, ColumnSpec value)

    • columnPut

      public String columnPut(String key, Size value)

    • columnRemove

      public String columnRemove(String key)
      Removes the column value mapping for this key from this map if it is present.

      Returns the value to which the map previously associated the key, or null if the map contained no mapping for this key. The map will not contain a String mapping for the specified key once the call returns.

      Parameters:
      key - key whose mapping is to be removed from the map.
      Returns:
      previous value associated with specified key, or null if there was no mapping for key.
      Throws:
      NullPointerException - if key is null.
      See Also:

    • rowContainsKey

      public boolean rowContainsKey(String key)
      Returns true if this map or a parent map - if any - contains a RowSpec mapping for the specified key.
      Parameters:
      key - key whose presence in this LayoutMap chain is to be tested.
      Returns:
      true if this map contains a row mapping for the specified key.
      Throws:
      NullPointerException - if the key is null.
      See Also:

    • rowGet

      public String rowGet(String key)
      Looks up and returns the RowSpec associated with the given key. First looks for an association in this LayoutMap. If there's no association, the lookup continues with the parent map - if any.
      Parameters:
      key - key whose associated value is to be returned.
      Returns:
      the row specification associated with the key, or null if no LayoutMap in the parent chain contains an association.
      Throws:
      NullPointerException - if key is null
      See Also:

    • rowPut

      public String rowPut(String key, String value)

    • rowPut

      public String rowPut(String key, RowSpec value)
      Associates the specified ColumnSpec with the specified key in this map. If the map previously contained a mapping for this key, the old value is replaced by the specified value. The RowSpec set in this map override an association - if any - in the chain of parent LayoutMaps.

      The RowSpec must not be null. To remove an association from this map use rowRemove(String).

      Parameters:
      key - key with which the specified value is to be associated.
      value - ColumnSpec to be associated with the specified key.
      Returns:
      previous ColumnSpec associated with specified key, or null if there was no mapping for key.
      Throws:
      NullPointerException - if the key or value is null.
      See Also:

    • rowPut

      public String rowPut(String key, Size value)

    • rowRemove

      public String rowRemove(String key)
      Removes the row value mapping for this key from this map if it is present.

      Returns the value to which the map previously associated the key, or null if the map contained no mapping for this key. The map will not contain a String mapping for the specified key once the call returns.

      Parameters:
      key - key whose mapping is to be removed from the map.
      Returns:
      previous value associated with specified key, or null if there was no mapping for key.
      Throws:
      NullPointerException - if key is null.
      See Also:

    • toString

      public String toString()
      Returns a string representation of this LayoutMap that lists the column and row associations.
      Overrides:
      toString in class Object
      Returns:
      a string representation