Map colors into names and vice versa.

       
/**
 * 
 * LibSparkline : a free Java sparkline chart library
 * 
 *
 * Project Info:  http://reporting.pentaho.org/libsparkline/
 *
 * (C) Copyright 2008, by Larry Ogrodnek, Pentaho Corporation and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the Apache License 2.0.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * You should have received a copy of the Apache License 2.0 along with this library;
 * if not, a online version is available at http://www.apache.org/licenses/
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------
 * ColorUtilitiy.java
 * ------------
 */

import java.awt.Color;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;

/**
 * A helper class to map colors into names and vice versa.
 * 
 * @author Thomas Morgner
 */
public final class ColorUtilitiy {
  private static final HashMap knownColorNamesByColor;

  private static final HashMap knownColorsByName;

  static {
    knownColorNamesByColor = new HashMap();
    knownColorsByName = new HashMap();
    try {
      final Field[] fields = Color.class.getFields();
      for (int i = 0; i < fields.length; i++) {
        final Field f = fields[i];
        if (Modifier.isPublic(f.getModifiers()) && Modifier.isFinal(f.getModifiers())
            && Modifier.isStatic(f.getModifiers())) {
          final String name = f.getName();
          final Object oColor = f.get(null);
          if (oColor instanceof Color) {
            knownColorNamesByColor.put(oColor, name.toLowerCase());
            knownColorsByName.put(name.toLowerCase(), oColor);
          }
        }
      }
    } catch (Exception e) {
      // ignore ..
    }
  }

  /**
   * Utility class constructor prevents object creation.
   */
  private ColorUtilitiy() {
  }

  /**
   * Parse a String into a Color. <p/> This method will accept either a color
   * name (a field name from {@link Color}, case insensitive e.g. "red"), or a
   * HTML hex color string (e.g. "#ff0000" for Color.RED).
   * 
   * @param value
   *          String to parse for color name or color number.
   * @return Color for s.
   */
  private static Color parseColor(final String value) {
    if (value == null) {
      return null;
    }

    final Object o = knownColorsByName.get(value.toLowerCase());
    if (o != null) {
      return (Color) o;
    }

    try {
      // get color by hex or octal value
      return Color.decode(value.trim());
    } catch (NumberFormatException nfe) {
      return null;
    }
  }

  /**
   * Parse a String into a Color, and returns the given default value if the
   * color is not parsable. <p/> This method will accept either a color name (a
   * field name from {@link Color}, case insensitive e.g. "red"), or a HTML hex
   * color string (e.g. "#ff0000" for Color.RED).
   * 
   * @param colorText
   *          String to parse for color name or color number.
   * @param defValue
   *          the default value that should be returned if the string is not
   *          parseable or null.
   * @return Color for the text.
   */
  public static Color convertColor(final String colorText, final Color defValue) {
    if (colorText == null || colorText.isEmpty()) {
      return defValue;
    }

    final Color retval = parseColor(colorText);
    if (retval == null) {
      return defValue;
    }
    return retval;
  }
}

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Map colors into names and vice versa. : Color « 2D Graphics GUI « Java

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