diff --git a/com.ibm.wala.core/src/com/ibm/wala/cfg/ControlFlowGraph.java b/com.ibm.wala.core/src/com/ibm/wala/cfg/ControlFlowGraph.java
index 56c0317cb..9a53c5fa0 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/cfg/ControlFlowGraph.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/cfg/ControlFlowGraph.java
@@ -19,9 +19,6 @@ import com.ibm.wala.util.intset.BitVector;
 
 /**
  * An interface that is common to the Shrike and SSA CFG implementations.
- * 
- * @author cahoon
- * @author sfink
  */
 public interface ControlFlowGraph<I, T extends IBasicBlock<I>> extends NumberedGraph<T> {
 
@@ -41,8 +38,7 @@ public interface ControlFlowGraph<I, T extends IBasicBlock<I>> extends NumberedG
   public BitVector getCatchBlocks();
 
   /**
-   * @param index
-   *          an instruction index
+   * @param index an instruction index
    * @return the basic block which contains this instruction.
    */
   public T getBlockForInstruction(int index);
@@ -54,10 +50,9 @@ public interface ControlFlowGraph<I, T extends IBasicBlock<I>> extends NumberedG
 
   /**
    * TODO: move this into IR?
-   * @param index
-   *          an instruction index
-   * @return the program counter (bytecode index) corresponding to that
-   *         instruction
+   * 
+   * @param index an instruction index
+   * @return the program counter (bytecode index) corresponding to that instruction
    */
   public int getProgramCounter(int index);
 
@@ -67,30 +62,26 @@ public interface ControlFlowGraph<I, T extends IBasicBlock<I>> extends NumberedG
   public IMethod getMethod();
 
   /**
-   * The order of blocks returned must indicate the exception-handling scope.
-   * So the first block is the first candidate catch block, and so on.
-   * With this invariant one can compute the exceptional control flow for
-   * a given exception type.
+   * The order of blocks returned must indicate the exception-handling scope. So the first block is the first candidate catch block,
+   * and so on. With this invariant one can compute the exceptional control flow for a given exception type.
    * 
-   * @return the basic blocks which may be reached from b via exceptional
-   *         control flow
+   * @return the basic blocks which may be reached from b via exceptional control flow
    */
   public List<T> getExceptionalSuccessors(T b);
 
   /**
    * The order of blocks returned should be arbitrary but deterministic.
+   * 
    * @param b
-   * @return the basic blocks which may be reached from b via normal control
-   *         flow
+   * @return the basic blocks which may be reached from b via normal control flow
    */
   public Collection<T> getNormalSuccessors(T b);
-  
+
   /**
    * The order of blocks returned should be arbitrary but deterministic.
    * 
    * @param b
-   * @return the basic blocks from which b may be reached via exceptional
-   *         control flow
+   * @return the basic blocks from which b may be reached via exceptional control flow
    */
   public Collection<T> getExceptionalPredecessors(T b);
 
@@ -98,8 +89,7 @@ public interface ControlFlowGraph<I, T extends IBasicBlock<I>> extends NumberedG
    * The order of blocks returned should be arbitrary but deterministic.
    * 
    * @param b
-   * @return the basic blocks from which b may be reached via normal
-   *         control flow
+   * @return the basic blocks from which b may be reached via normal control flow
    */
   public Collection<T> getNormalPredecessors(T b);
 }
diff --git a/com.ibm.wala.core/src/com/ibm/wala/eclipse/AbstractJavaAnalysisAction.java b/com.ibm.wala.core/src/com/ibm/wala/eclipse/AbstractJavaAnalysisAction.java
index 9871b2407..43040f798 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/eclipse/AbstractJavaAnalysisAction.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/eclipse/AbstractJavaAnalysisAction.java
@@ -62,6 +62,9 @@ public abstract class AbstractJavaAnalysisAction implements IObjectActionDelegat
   }
 
   public static AnalysisScope computeScope(IStructuredSelection selection, boolean includeSource) throws IOException {
+    if (selection == null) {
+      throw new IllegalArgumentException("null selection");
+    }
     Collection<EclipseProjectPath> projectPaths = new LinkedList<EclipseProjectPath>();
     for (Iterator it = selection.iterator(); it.hasNext();) {
       Object object = it.next();
diff --git a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/AnalysisScope.java b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/AnalysisScope.java
index faae5d1ce..e5f5153c2 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/AnalysisScope.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/AnalysisScope.java
@@ -349,6 +349,9 @@ public class AnalysisScope {
    * Utility function. Useful when parsing input.
    */
   public MethodReference findMethod(Atom loader, String klass, Atom name, ImmutableByteArray desc) {
+    if (desc == null) {
+      throw new IllegalArgumentException("null desc");
+    }
     ClassLoaderReference clr = getLoader(loader);
     Descriptor ddesc = Descriptor.findOrCreate(languages.get(clr.getLanguage()), desc);
     TypeReference type = TypeReference.findOrCreate(clr, TypeName.string2TypeName(klass));
diff --git a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/PointsToMap.java b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/PointsToMap.java
index 6ee8e8081..a63d90dc0 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/PointsToMap.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/ipa/callgraph/propagation/PointsToMap.java
@@ -145,6 +145,9 @@ public class PointsToMap {
    * points-to-sets are the primordial assignments from which the transitive closure flows.
    */
   public void recordTransitiveRoot(PointerKey key) {
+    if (key == null) {
+      throw new IllegalArgumentException("null key");
+    }
     int i = findOrCreateIndex(key);
     transitiveRoots.set(i);
   }
diff --git a/com.ibm.wala.core/src/com/ibm/wala/properties/WalaProperties.java b/com.ibm.wala.core/src/com/ibm/wala/properties/WalaProperties.java
index d1a631cb1..dafedbcae 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/properties/WalaProperties.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/properties/WalaProperties.java
@@ -113,6 +113,9 @@ public final class WalaProperties {
     if (loader == null) {
       throw new IllegalArgumentException("loader is null");
     }
+    if (fileName == null) {
+      throw new IllegalArgumentException("null fileName");
+    }
     final InputStream propertyStream = loader.getResourceAsStream(fileName);
     if (propertyStream == null) {
       throw new IOException("property_file_unreadable " + fileName);
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/AbstractNumberedGraph.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/AbstractNumberedGraph.java
index 1631a8c0a..5d41024d8 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/AbstractNumberedGraph.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/AbstractNumberedGraph.java
@@ -16,11 +16,8 @@ import com.ibm.wala.util.graph.impl.NumberedNodeIterator;
 import com.ibm.wala.util.intset.IntSet;
 
 /**
- * 
  * Basic functionality for a graph that delegates node and edge management, and
  * tracks node numbers
- * 
- * @author sfink
  */
 public abstract class AbstractNumberedGraph<T> extends AbstractGraph<T> implements NumberedGraph<T> {
 
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/impl/DelegatingNumberedNodeManager.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/impl/DelegatingNumberedNodeManager.java
index 567705a4b..736f4e562 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/impl/DelegatingNumberedNodeManager.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/impl/DelegatingNumberedNodeManager.java
@@ -163,6 +163,9 @@ public class DelegatingNumberedNodeManager<T extends INodeWithNumber> implements
     }
     INodeWithNumber N = n;
     int number = N.getGraphNodeId();
+    if (number == -1) {
+      throw new IllegalArgumentException("Cannot remove node, not in graph");
+    }
     if (nodes[number] != null) {
       nodes[number] = null;
       numberOfNodes--;
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSIterator.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSIterator.java
index cbb19803c..bcc296398 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSIterator.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSIterator.java
@@ -77,6 +77,9 @@ public class BFSIterator<T> implements Iterator<T> {
     if (G == null) {
       throw new IllegalArgumentException("G is null");
     }
+    if (nodes == null) {
+      throw new IllegalArgumentException("nodes is null");
+    }
     init(G, nodes);
   }
 
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSPathFinder.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSPathFinder.java
index 85e6fce10..4ce134994 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSPathFinder.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BFSPathFinder.java
@@ -26,14 +26,12 @@ import com.ibm.wala.util.debug.Trace;
 import com.ibm.wala.util.graph.Graph;
 
 /**
- * This class searches breadth-first for node that matches some criteria. If
- * found, it reports a path to the first node found.
+ * This class searches breadth-first for node that matches some criteria. If found, it reports a path to the first node found.
  * 
- * This class follows the outNodes of the graph nodes to define the graph, but
- * this behavior can be changed by overriding the getConnected method.
+ * This class follows the outNodes of the graph nodes to define the graph, but this behavior can be changed by overriding the
+ * getConnected method.
  * 
- * TODO: if finding many paths, use a dynamic programming algorithm instead of
- * calling this repeatedly.
+ * TODO: if finding many paths, use a dynamic programming algorithm instead of calling this repeatedly.
  * 
  * @author Stephen Fink
  */
@@ -57,28 +55,27 @@ public class BFSPathFinder<T> {
   final private Iterator<T> roots;
 
   /**
-   * Construct a breadth-first enumerator starting with a particular node in a
-   * directed graph.
+   * Construct a breadth-first enumerator starting with a particular node in a directed graph.
    * 
-   * @param G
-   *          the graph whose nodes to enumerate
+   * @param G the graph whose nodes to enumerate
    */
   public BFSPathFinder(Graph<T> G, T N, Filter<T> f) {
     if (G == null) {
       throw new IllegalArgumentException("G is null");
     }
+    if (f == null) {
+      throw new IllegalArgumentException("null f");
+    }
     this.G = G;
     this.roots = new NonNullSingletonIterator<T>(N);
     this.filter = f;
   }
 
   /**
-   * Construct a breadth-first enumerator starting with a particular node in a
-   * directed graph.
+   * Construct a breadth-first enumerator starting with a particular node in a directed graph.
    * 
-   * @param G
-   *          the graph whose nodes to enumerate
-   * @throws IllegalArgumentException  if G is null
+   * @param G the graph whose nodes to enumerate
+   * @throws IllegalArgumentException if G is null
    */
   public BFSPathFinder(Graph<T> G, T src, final T target) throws IllegalArgumentException {
     if (G == null) {
@@ -97,11 +94,9 @@ public class BFSPathFinder<T> {
   }
 
   /**
-   * Construct a breadth-first enumerator starting with a particular node in a
-   * directed graph.
+   * Construct a breadth-first enumerator starting with a particular node in a directed graph.
    * 
-   * @param G
-   *          the graph whose nodes to enumerate
+   * @param G the graph whose nodes to enumerate
    */
   public BFSPathFinder(Graph<T> G, T src, Iterator<T> targets) {
     if (targets == null) {
@@ -123,11 +118,9 @@ public class BFSPathFinder<T> {
   }
 
   /**
-   * Construct a breadth-first enumerator starting with any of a set of nodes in
-   * a directed graph.
+   * Construct a breadth-first enumerator starting with any of a set of nodes in a directed graph.
    * 
-   * @param G
-   *          the graph whose nodes to enumerate
+   * @param G the graph whose nodes to enumerate
    */
   public BFSPathFinder(Graph<T> G, Iterator<T> sources, final T target) {
     if (G == null) {
@@ -146,11 +139,10 @@ public class BFSPathFinder<T> {
   }
 
   /**
-   * Construct a breadth-first enumerator across the (possibly improper) subset
-   * of nodes reachable from the nodes in the given enumeration.
+   * Construct a breadth-first enumerator across the (possibly improper) subset of nodes reachable from the nodes in the given
+   * enumeration.
    * 
-   * @param nodes
-   *          the set of nodes from which to start searching
+   * @param nodes the set of nodes from which to start searching
    */
   public BFSPathFinder(Graph<T> G, Iterator<T> nodes, Filter<T> f) {
     this.G = G;
@@ -165,8 +157,8 @@ public class BFSPathFinder<T> {
   }
 
   /**
-   * @return a List of nodes that specifies the first path found from a root to
-   *         a node accepted by the filter. Returns null if no path found.
+   * @return a List of nodes that specifies the first path found from a root to a node accepted by the filter. Returns null if no
+   *         path found.
    */
   public List<T> find() {
 
@@ -199,8 +191,7 @@ public class BFSPathFinder<T> {
   }
 
   /**
-   * @return a List which represents a path in the breadth-first search to Q[i].
-   *         Q holds the nodes visited during the BFS, in order.
+   * @return a List which represents a path in the breadth-first search to Q[i]. Q holds the nodes visited during the BFS, in order.
    */
   private List<T> makePath(T node, Map<Object, T> history) {
     ArrayList<T> result = new ArrayList<T>();
@@ -220,8 +211,7 @@ public class BFSPathFinder<T> {
   /**
    * get the out edges of a given node
    * 
-   * @param n
-   *          the node of which to get the out edges
+   * @param n the node of which to get the out edges
    * @return the out edges
    * 
    */
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BoundedBFSIterator.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BoundedBFSIterator.java
index a4f438da9..9eef8ae0e 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BoundedBFSIterator.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/BoundedBFSIterator.java
@@ -93,6 +93,9 @@ public class BoundedBFSIterator<T> implements Iterator<T> {
     if (G == null) {
       throw new IllegalArgumentException("G is null");
     }
+    if (k < 0) {
+      throw new IllegalArgumentException("invalid k: " + k);
+    }
     this.k = k;
     boundary = new int[k];
     init(G, nodes);
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/DFS.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/DFS.java
index 4c1ed8821..dbf34a5ab 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/DFS.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/DFS.java
@@ -74,24 +74,6 @@ public class DFS {
     return result;
   }
 
-  // need to comment this out to avoid ambiguous type failure from javac
-  // /**
-  // * Perform a DFS starting with a particular node and return the set of all
-  // * nodes visited.
-  // *
-  // * @param G
-  // * the graph containing n
-  // * @param n
-  // * @return Set
-  // */
-  // public static <T> Set<T> getReachableNodes(Graph<T> G, T n) {
-  // HashSet<T> result = HashSetFactory.make();
-  // Iterator<T> dfs = iterateFinishTime(G, new NonNullSingletonIterator<T>(n));
-  // while (dfs.hasNext()) {
-  // result.add(dfs.next());
-  // }
-  // return result;
-  // }
 
   /**
    * Perform a DFS and return the set of all nodes visited.
@@ -200,7 +182,7 @@ public class DFS {
   }
 
   /**
-   * @param G
+   * @param G a graph
    * @return iterator of nodes of G in order of DFS finish time
    * @throws IllegalArgumentException if G == null
    */
@@ -216,30 +198,18 @@ public class DFS {
   }
 
   /**
-   * @param G
+   * @param G a graph
    * @param ie roots of traversal, in order to visit in outermost loop of DFS
    * @return iterator of nodes of G in order of DFS finish time
    */
   public static <T> DFSFinishTimeIterator<T> iterateFinishTime(Graph<T> G, Iterator<? extends T> ie) {
+    if (ie == null) {
+      throw new IllegalArgumentException("null ie");
+    }
     if (G instanceof NumberedGraph) {
       return new NumberedDFSFinishTimeIterator<T>((NumberedGraph<T>) G, ie);
     } else {
       return new SlowDFSFinishTimeIterator<T>(G, ie);
     }
   }
-
-  // need to comment out to avoid ambiguous type error from javac
-  // /**
-  // * @param G
-  // * @param n
-  // * @return iterator of nodes of G in order of DFS finish time
-  // */
-  // public static <T> DFSFinishTimeIterator<T> iterateFinishTime(Graph<T> G, T
-  // n) {
-  // if (G instanceof NumberedGraph) {
-  // return new NumberedDFSFinishTimeIterator<T>((NumberedGraph<T>) G, n);
-  // } else {
-  // return new SlowDFSFinishTimeIterator<T>(G, n);
-  // }
-  // }
 }
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/SlowDFSDiscoverTimeIterator.java b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/SlowDFSDiscoverTimeIterator.java
index 6ab59d83d..0b985f502 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/SlowDFSDiscoverTimeIterator.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/graph/traverse/SlowDFSDiscoverTimeIterator.java
@@ -60,6 +60,9 @@ public class SlowDFSDiscoverTimeIterator<T> extends GraphDFSDiscoverTimeIterator
    * @param nodes the set of nodes from which to start searching
    */
   public SlowDFSDiscoverTimeIterator(Graph<T> G, Iterator<T> nodes) {
+    if (nodes == null) {
+      throw new IllegalArgumentException("null nodes");
+    }
     init(G, nodes);
   }
 
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/intset/BitVectorIntSet.java b/com.ibm.wala.core/src/com/ibm/wala/util/intset/BitVectorIntSet.java
index 014c1c1fc..babe06a0c 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/intset/BitVectorIntSet.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/intset/BitVectorIntSet.java
@@ -219,6 +219,9 @@ public final class BitVectorIntSet implements MutableIntSet {
    * @see com.ibm.wala.util.intset.IntSet#foreach(com.ibm.wala.util.intset.IntSetAction)
    */
   public void foreach(IntSetAction action) {
+    if (action == null) {
+      throw new IllegalArgumentException("null action");
+    }
     int nextBit = bitVector.nextSetBit(0);
     populationCount = (populationCount == UNDEFINED) ? bitVector.populationCount() : populationCount;
     for (int i = 0; i < populationCount; i++) {
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntSet.java b/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntSet.java
index d460d1814..232e78817 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntSet.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntSet.java
@@ -11,10 +11,7 @@
 package com.ibm.wala.util.intset;
 
 /**
- * 
  * Set of integers; not necessary mutable TODO: extract a smaller interface?
- * 
- * @author sfink
  */
 public interface IntSet {
 
@@ -60,15 +57,11 @@ public interface IntSet {
 
   /**
    * Invoke an action on each element of the Set
-   * 
-   * @param action
    */
   public void foreach(IntSetAction action);
 
   /**
    * Invoke an action on each element of the Set, excluding elements of Set X
-   * 
-   * @param action
    */
   public void foreachExcluding(IntSet X, IntSetAction action);
 
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntegerUnionFind.java b/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntegerUnionFind.java
index 0d4ffaa35..0dddc8e83 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntegerUnionFind.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/intset/IntegerUnionFind.java
@@ -36,10 +36,10 @@ public class IntegerUnionFind {
   }
 
   /**
-   * @param size
+   * @param size initial size of the tables
    */
   public IntegerUnionFind(int size) {
-    if (size + 1 < 0) {
+    if (size  < 0) {
       throw new IllegalArgumentException("illegal size: " + size);
     }
     parent = new int[size + 1];
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/intset/SparseLongSet.java b/com.ibm.wala.core/src/com/ibm/wala/util/intset/SparseLongSet.java
index 89164ff62..af957643f 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/intset/SparseLongSet.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/intset/SparseLongSet.java
@@ -414,7 +414,7 @@ public class SparseLongSet implements LongSet {
     if (elements == null) {
       throw new IllegalStateException("Illegal to ask max() on an empty int set");
     }
-    return elements[size - 1];
+    return (size > 0) ? elements[size - 1] : -1;
   }
 
   /**
diff --git a/com.ibm.wala.core/src/com/ibm/wala/util/io/FileProvider.java b/com.ibm.wala.core/src/com/ibm/wala/util/io/FileProvider.java
index 6fe5e2609..486174160 100644
--- a/com.ibm.wala.core/src/com/ibm/wala/util/io/FileProvider.java
+++ b/com.ibm.wala.core/src/com/ibm/wala/util/io/FileProvider.java
@@ -95,6 +95,9 @@ public class FileProvider {
   }
 
   public static URL getResource(String fileName, ClassLoader loader) throws IOException {
+    if (fileName == null) {
+      throw new IllegalArgumentException("null fileName");
+    }
     if (CorePlugin.getDefault() == null && loader == null) {
       throw new IllegalArgumentException("null loader");
     }
@@ -215,6 +218,9 @@ public class FileProvider {
     if (loader == null) {
       throw new IllegalArgumentException("null loader");
     }
+    if (fileName == null) {
+      throw new IllegalArgumentException("null fileName");
+    }
     URL url = loader.getResource(fileName);
     if (DEBUG_LEVEL > 0) {
       Trace.println("FileProvider got url: " + url + " for " + fileName);