Source for javax.swing.tree.TreePath

   1: /* TreePath.java --
   2:    Copyright (C) 2002, 2005, 2006,  Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package javax.swing.tree;
  40: 
  41: import java.io.Serializable;
  42: import java.util.Arrays;
  43: 
  44: /**
  45:  * A <code>TreePath</code> represents a sequence of tree elements that form
  46:  * a path starting from the root of a tree.  A tree element can be represented
  47:  * by any {@link Object}.
  48:  * 
  49:  * @author Andrew Selkirk
  50:  */
  51: public class TreePath implements Serializable
  52: {
  53:   static final long serialVersionUID = 4380036194768077479L;
  54: 
  55:   /**
  56:    * The actual patch. The {@link DefaultTreeSelectionModel#clone()}
  57:    * assumes that the TreePath is immutable, so it is marked final here.
  58:    */
  59:   private final Object[] path;
  60:   
  61:   /**
  62:    * The parent path (to be reused).
  63:    */
  64:   private transient TreePath parentPath;
  65: 
  66: 
  67:   /**
  68:    * Creates a path from the list of objects representing tree elements.  The
  69:    * incoming array is copied so that subsequent changes do not affect this
  70:    * tree path.
  71:    * 
  72:    * @param path  the elements in the path (<code>null</code> not permitted).
  73:    * 
  74:    * @throws IllegalArgumentException if <code>path</code> is <code>null</code>.
  75:    */
  76:   public TreePath(Object[] path)
  77:   {
  78:     if (path == null)
  79:       throw new IllegalArgumentException("Null 'path' not permitted.");
  80:     this.path = new Object[path.length];
  81:     System.arraycopy(path, 0, this.path, 0, path.length);
  82:   }
  83: 
  84:   /**
  85:    * Creates a new path from a single element.
  86:    * 
  87:    * @param element the element (<code>null</code> not permitted).
  88:    * 
  89:    * @throws IllegalArgumentException if <code>element</code> is 
  90:    *         <code>null</code>.
  91:    */
  92:   public TreePath(Object element)
  93:   {
  94:     path = new Object[1];
  95:     path[0] = element;
  96:   }
  97: 
  98:   /**
  99:    * Creates a new tree path by adding the specified <code>element</code> to
 100:    * the <code>path</code>.
 101:    * 
 102:    * @param path  a tree path.
 103:    * @param element  a path element.
 104:    */
 105:   protected TreePath(TreePath path, Object element)
 106:   {
 107:     if (element == null)
 108:       throw new NullPointerException("Null 'element' argument.");
 109:     Object[] treepath = path.getPath();
 110: 
 111:     // Create Tree Path
 112:     this.path = new Object[treepath.length + 1];
 113:     System.arraycopy(treepath, 0, this.path, 0, treepath.length);
 114:     this.path[treepath.length] = element;
 115:   }
 116: 
 117:   /**
 118:    * Creates a new tree path using the first <code>length</code> elements
 119:    * from the given array.
 120:    * 
 121:    * @param path  the path elements.
 122:    * @param length  the path length.
 123:    */
 124:   protected TreePath(Object[] path, int length)
 125:   {
 126:     // Create Path
 127:     this.path = new Object[length];
 128:     System.arraycopy(path, 0, this.path, 0, length);
 129:   }
 130: 
 131:   /**
 132:    * Default constructor.
 133:    */
 134:   protected TreePath()
 135:   {
 136:     path = new Object[0];
 137:   }
 138: 
 139: 
 140:   /**
 141:    * Returns a hashcode for the path.
 142:    * 
 143:    * @return A hashcode.
 144:    */
 145:   public int hashCode()
 146:   {
 147:     return getLastPathComponent().hashCode();
 148:   }
 149: 
 150:   /**
 151:    * Tests this path for equality with an arbitrary object.  An object is 
 152:    * considered equal to this path if and only if:
 153:    * <ul>
 154:    * <li>the object is not <code>null</code>;</li>
 155:    * <li>the object is an instanceof {@link TreePath};</li>
 156:    * <li>the object contains the same elements in the same order as this
 157:    * {@link TreePath};</li>
 158:    * </ul>
 159:    * 
 160:    * @param object  the object (<code>null</code> permitted).
 161:    * 
 162:    * @return <code>true</code> if <code>obj</code> is equal to this tree path,
 163:    *         and <code>false</code> otherwise.
 164:    */
 165:   public boolean equals(Object object)
 166:   {
 167:     Object[] treepath;
 168:     int index;
 169: 
 170:     if (object instanceof TreePath)
 171:       {
 172:         treepath = ((TreePath) object).getPath();
 173:         if (treepath.length != path.length)
 174:           return false;
 175:         for (index = 0; index < path.length; index++)
 176:           {
 177:             if (!path[index].equals(treepath[index]))
 178:               return false;
 179:           }
 180: 
 181:         // Tree Path's are equals
 182:         return true;
 183:       }
 184: 
 185:     // Unequal
 186:     return false;
 187:   }
 188: 
 189:   /**
 190:    * Returns a string representation of this path.
 191:    * 
 192:    * @return A string representation of this path.
 193:    */
 194:   public String toString()
 195:   {
 196:     if (path.length == 1)
 197:       return String.valueOf(path[0]);
 198:     else
 199:       return Arrays.asList(path).toString();
 200:   }
 201: 
 202:   /**
 203:    * Returns an array containing the path elements.
 204:    * 
 205:    * @return An array containing the path elements.
 206:    */
 207:   public Object[] getPath()
 208:   {
 209:     return (Object[]) path.clone();
 210:   }
 211: 
 212:   /**
 213:    * Returns the last object in the path.
 214:    * 
 215:    * @return The last object in the path.
 216:    */
 217:   public Object getLastPathComponent()
 218:   {
 219:     return path[path.length - 1];
 220:   }
 221: 
 222:   /**
 223:    * Returns the number of elements in the path.
 224:    * 
 225:    * @return The number of elements in the path.
 226:    */
 227:   public int getPathCount()
 228:   {
 229:     return path.length;
 230:   }
 231: 
 232:   /**
 233:    * Returns the element at the specified position in the path.
 234:    * 
 235:    * @param position the element position (<code>0 &lt N - 1</code>, where 
 236:    *                 <code>N</code> is the number of elements in the path).
 237:    * 
 238:    * @return The element at the specified position.
 239:    * 
 240:    * @throws IllegalArgumentException if <code>position</code> is outside the
 241:    *         valid range.
 242:    */
 243:   public Object getPathComponent(int position)
 244:   {
 245:     if (position < 0 || position >= getPathCount()) 
 246:       throw new IllegalArgumentException("Invalid position: " + position);
 247:     return path[position];
 248:   }
 249: 
 250:   /**
 251:    * Returns <code>true</code> if <code>path</code> is a descendant of this
 252:    * path, and <code>false</code> otherwise.  If <code>path</code> is 
 253:    * <code>null</code>, this method returns <code>false</code>.
 254:    * 
 255:    * @param path  the path to check (<code>null</code> permitted).
 256:    * 
 257:    * @return <code>true</code> if <code>path</code> is a descendant of this
 258:    *         path, and <code>false</code> otherwise
 259:    */
 260:   public boolean isDescendant(TreePath path)
 261:   {
 262:     if (path == null)
 263:       return false;
 264:     int count = getPathCount();
 265:     int otherPathLength = path.getPathCount();
 266:     if (otherPathLength < count)
 267:       return false;
 268:     while (otherPathLength > count)
 269:       {
 270:         otherPathLength--;
 271:         path = path.getParentPath();
 272:       }
 273:     
 274:     return equals(path);
 275:   }
 276: 
 277:   /**
 278:    * Creates a new path that is equivalent to this path plus the specified
 279:    * element.
 280:    * 
 281:    * @param element  the element.
 282:    * 
 283:    * @return A tree path.
 284:    */
 285:   public TreePath pathByAddingChild(Object element)
 286:   {
 287:     return new TreePath(this, element);
 288:   }
 289: 
 290:   /**
 291:    * Returns the parent path, which is a path containing all the same elements
 292:    * as this path, except for the last one.  If this path contains only one
 293:    * element, the method returns <code>null</code>.
 294:    * 
 295:    * @return The parent path, or <code>null</code> if this path has only one
 296:    *         element.
 297:    */
 298:   public TreePath getParentPath()
 299:   {
 300:     // If this path has only one element, then we return null. That
 301:     // is what the JDK does.
 302:     if (path.length <= 1)
 303:       return null;
 304:     
 305:     // Reuse the parent path, if possible. The parent path is requested
 306:     // during the tree repainting, so reusing generates a lot less garbage.
 307:     if (parentPath == null)
 308:       parentPath = new TreePath(this.getPath(), path.length - 1);
 309:     
 310:     return parentPath;
 311:   }
 312: }