Add addClass, removeClass, toggleClass, hasClass to Element and Eleme…

…nts.

Closes #2

src/main/java/org/jsoup/nodes/Element.java

@@ -1,6 +1,7 @@
 package org.jsoup.nodes;
 
 import org.apache.commons.lang.Validate;
+import org.apache.commons.lang.StringUtils;
 import org.jsoup.parser.Parser;
 import org.jsoup.parser.Tag;
 import org.jsoup.select.Collector;
@@ -602,17 +603,29 @@ public String className() {
 
     /**
      * Get all of the element's class names. E.g. on element {@code <div class="header gray"}>},
-     * returns a set of two elements {@code "header", "gray"}.
+     * returns a set of two elements {@code "header", "gray"}. Note that modifications to this set are not pushed to
+     * the backing {@code class} attribute; use the {@link #classNames(java.util.Set)} method to persist them.
      * @return set of classnames, empty if no class attribute
      */
     public Set<String> classNames() {
         if (classNames == null) {
             String[] names = className().split("\\s+");
-            classNames = new HashSet<String>(Arrays.asList(names));
+            classNames = new LinkedHashSet<String>(Arrays.asList(names));
         }
         return classNames;
     }
 
+    /**
+     Set the element's {@code class} attribute to the supplied class names.
+     @param classNames set of classes
+     @return this element, for chaining
+     */
+    public Element classNames(Set<String> classNames) {
+        Validate.notNull(classNames);
+        attributes.put("class", StringUtils.join(classNames, " "));
+        return this;
+    }
+
     /**
      * Tests if this element has a class.
      * @param className name of class to check for
@@ -622,6 +635,54 @@ public boolean hasClass(String className) {
         return classNames().contains(className);
     }
 
+    /**
+     Add a class name to this element's {@code class} attribute.
+     @param className class name to add
+     @return this element
+     */
+    public Element addClass(String className) {
+        Validate.notNull(className);
+
+        Set<String> classes = classNames();
+        classes.add(className);
+        classNames(classes);
+
+        return this;
+    }
+
+    /**
+     Remove a class name from this element's {@code class} attribute.
+     @param className class name to remove
+     @return this element
+     */
+    public Element removeClass(String className) {
+        Validate.notNull(className);
+
+        Set<String> classes = classNames();
+        classes.remove(className);
+        classNames(classes);
+
+        return this;
+    }
+
+    /**
+     Toggle a class name on this element's {@code class} attribute: if present, remove it; otherwise add it.
+     @param className class name to toggle
+     @return this element
+     */
+    public Element toggleClass(String className) {
+        Validate.notNull(className);
+
+        Set<String> classes = classNames();
+        if (classes.contains(className))
+            classes.remove(className);
+        else
+            classes.add(className);
+        classNames(classes);
+
+        return this;
+    }
+
     void outerHtml(StringBuilder accum) {
 
         accum

src/main/java/org/jsoup/select/Elements.java

@@ -41,12 +41,16 @@ public String attr(String attributeKey) {
     }
 
     /**
-     Checks if the first matched value has this attribute set.
+     Checks if any of the matched elements have this attribute set.
      @param attributeKey attribute key
-     @return true if the first element has the attribute; false if it doesn't, or if no elements were matched.
+     @return true if any of the elements have the attribute; false if none do.
      */
     public boolean hasAttr(String attributeKey) {
-        return !contents.isEmpty() && first().hasAttr(attributeKey);
+        for (Element element : contents) {
+            if (element.hasAttr(attributeKey))
+                return true;
+        }
+        return false;
     }
 
     /**
@@ -73,6 +77,55 @@ public Elements removeAttr(String attributeKey) {
         }
         return this;
     }
+
+    /**
+     Add the class name to every matched element's {@code class} attribute.
+     @param className class name to add
+     @return this
+     */
+    public Elements addClass(String className) {
+        for (Element element : contents) {
+            element.addClass(className);
+        }
+        return this;
+    }
+
+    /**
+     Remove the class name from every matched element's {@code class} attribute, if present.
+     @param className class name to remove
+     @return this
+     */
+    public Elements removeClass(String className) {
+        for (Element element : contents) {
+            element.removeClass(className);
+        }
+        return this;
+    }
+
+    /**
+     Toggle the class name on every matched element's {@code class} attribute.
+     @param className class name to add if missing, or remove if present, from every element.
+     @return this
+     */
+    public Elements toggleClass(String className) {
+        for (Element element : contents) {
+            element.toggleClass(className);
+        }
+        return this;
+    }
+
+    /**
+     Determine if any of the matched elements have this class name set in their {@code class} attribute.
+     @param className class name to check for
+     @return true if any do, false if none do
+     */
+    public boolean hasClass(String className) {
+        for (Element element : contents) {
+            if (element.hasClass(className))
+                return true;
+        }
+        return false;
+    }
 
     /**
      * Get the combined text of all the matched elements.

src/test/java/org/jsoup/nodes/ElementTest.java

@@ -150,6 +150,19 @@ public class ElementTest {
         assertFalse(doc.hasClass("mellow"));
     }
 
+    @Test public void testClassUpdates() {
+        Document doc = Jsoup.parse("<div class='mellow yellow'></div>");
+        Element div = doc.select("div").first();
+
+        div.addClass("green");
+        assertEquals("mellow yellow green", div.className());
+        div.removeClass("red"); // noop
+        div.removeClass("yellow");
+        assertEquals("mellow green", div.className());
+        div.toggleClass("green").toggleClass("red");
+        assertEquals("mellow red", div.className());
+    }
+
     @Test public void testOuterHtml() {
         Document doc = Jsoup.parse("<div title='Tags &amp;c.'><img src=foo.png><p><!-- comment -->Hello<p>there");
         assertEquals("<html><head></head><body><div title=\"Tags &amp;c.\"><img src=\"foo.png\" /><p><!-- comment -->Hello</p><p>there</p></div></body></html>",

src/test/java/org/jsoup/select/ElementsTest.java

@@ -37,6 +37,20 @@ public class ElementsTest {
         assertEquals("classy", ps.last().attr("style"));
         assertEquals("bar", ps.last().attr("class"));
     }
+
+    @Test public void classes() {
+        Document doc = Jsoup.parse("<div><p class='mellow yellow'></p><p class='red green'></p>");
+
+        Elements els = doc.select("p");
+        assertTrue(els.hasClass("red"));
+        assertFalse(els.hasClass("blue"));
+        els.addClass("blue");
+        els.removeClass("yellow");
+        els.toggleClass("mellow");
+
+        assertEquals("blue", els.get(0).className());
+        assertEquals("red green blue mellow", els.get(1).className());
+    }
 
     @Test public void text() {
         String h = "<div><p>Hello<p>there<p>world</div>";