Refactor and polish various Comparator impls

- Refactor CompoundComparator constructor to use varargs
 - Refactor MediaType to consume new varargs constructor
 - Add notNull assertions where appropriate
 - Add generic typing where appropriate
 - Suppress generics warnings elsewhere
 - Fix whitespace errors

spring-core/src/main/java/org/springframework/util/comparator/CompoundComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,6 +37,7 @@ import org.springframework.util.Assert;
  * @author Juergen Hoeller
  * @since 1.2.2
  */
+@SuppressWarnings("serial")
 public class CompoundComparator<T> implements Comparator<T>, Serializable {
 
 	private final List<InvertibleComparator<T>> comparators;
@@ -58,10 +59,12 @@ public class CompoundComparator<T> implements Comparator<T>, Serializable {
 	 * @param comparators the comparators to build into a compound comparator
 	 * @see InvertibleComparator
 	 */
-	public CompoundComparator(Comparator[] comparators) {
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	public CompoundComparator(Comparator... comparators) {
+		Assert.notNull(comparators, "Comparators must not be null");
 		this.comparators = new ArrayList<InvertibleComparator<T>>(comparators.length);
-		for (Comparator<T> comparator : comparators) {
+		for (Comparator comparator : comparators) {
-			addComparator(comparator);
+			this.addComparator(comparator);
 		}
 	}
 
@@ -123,7 +126,7 @@ public class CompoundComparator<T> implements Comparator<T>, Serializable {
 	 * comparator.
 	 */
 	public void invertOrder() {
-		for (InvertibleComparator comparator : this.comparators) {
+		for (InvertibleComparator<T> comparator : this.comparators) {
 			comparator.invertOrder();
 		}
 	}
@@ -159,7 +162,6 @@ public class CompoundComparator<T> implements Comparator<T>, Serializable {
 		return this.comparators.size();
 	}
 
-
 	public int compare(T o1, T o2) {
 		Assert.state(this.comparators.size() > 0,
 				"No sort definitions have been added to this CompoundComparator to compare");
@@ -173,6 +175,7 @@ public class CompoundComparator<T> implements Comparator<T>, Serializable {
 	}
 
 	@Override
+	@SuppressWarnings("unchecked")
 	public boolean equals(Object obj) {
 		if (this == obj) {
 			return true;
@@ -180,7 +183,7 @@ public class CompoundComparator<T> implements Comparator<T>, Serializable {
 		if (!(obj instanceof CompoundComparator)) {
 			return false;
 		}
-		CompoundComparator other = (CompoundComparator) obj;
+		CompoundComparator<T> other = (CompoundComparator<T>) obj;
 		return this.comparators.equals(other.comparators);
 	}
 

spring-core/src/main/java/org/springframework/util/comparator/InvertibleComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2005 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,15 +19,18 @@ package org.springframework.util.comparator;
 import java.io.Serializable;
 import java.util.Comparator;
 
+import org.springframework.util.Assert;
+
 /**
  * A decorator for a comparator, with an "ascending" flag denoting
  * whether comparison results should be treated in forward (standard
  * ascending) order or flipped for reverse (descending) order.
- * 
+ *
  * @author Keith Donald
  * @author Juergen Hoeller
  * @since 1.2.2
  */
+@SuppressWarnings("serial")
 public class InvertibleComparator<T> implements Comparator<T>, Serializable {
 
 	private final Comparator<T> comparator;
@@ -41,6 +44,7 @@ public class InvertibleComparator<T> implements Comparator<T>, Serializable {
 	 * @param comparator the comparator to decorate
 	 */
 	public InvertibleComparator(Comparator<T> comparator) {
+		Assert.notNull(comparator, "Comparator must not be null");
 		this.comparator = comparator;
 	}
 
@@ -51,6 +55,7 @@ public class InvertibleComparator<T> implements Comparator<T>, Serializable {
 	 * @param ascending the sort order: ascending (true) or descending (false)
 	 */
 	public InvertibleComparator(Comparator<T> comparator, boolean ascending) {
+		Assert.notNull(comparator, "Comparator must not be null");
 		this.comparator = comparator;
 		setAscending(ascending);
 	}
@@ -97,6 +102,7 @@ public class InvertibleComparator<T> implements Comparator<T>, Serializable {
 	}
 
 	@Override
+	@SuppressWarnings("unchecked")
 	public boolean equals(Object obj) {
 		if (this == obj) {
 			return true;
@@ -104,7 +110,7 @@ public class InvertibleComparator<T> implements Comparator<T>, Serializable {
 		if (!(obj instanceof InvertibleComparator)) {
 			return false;
 		}
-		InvertibleComparator other = (InvertibleComparator) obj;
+		InvertibleComparator<T> other = (InvertibleComparator<T>) obj;
 		return (this.comparator.equals(other.comparator) && this.ascending == other.ascending);
 	}
 

spring-core/src/main/java/org/springframework/util/comparator/NullSafeComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2005 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,7 +23,7 @@ import org.springframework.util.Assert;
 /**
  * A Comparator that will safely compare nulls to be lower or higher than
  * other objects. Can decorate a given Comparator or work on Comparables.
- * 
+ *
  * @author Keith Donald
  * @author Juergen Hoeller
  * @since 1.2.2
@@ -35,14 +35,15 @@ public class NullSafeComparator<T> implements Comparator<T> {
 	 * A shared default instance of this comparator, treating nulls lower
 	 * than non-null objects.
 	 */
-	public static final NullSafeComparator NULLS_LOW = new NullSafeComparator(true);
+	@SuppressWarnings("rawtypes")
+	public static final NullSafeComparator NULLS_LOW = new NullSafeComparator<Object>(true);
 
 	/**
 	 * A shared default instance of this comparator, treating nulls higher
 	 * than non-null objects.
 	 */
-	public static final NullSafeComparator NULLS_HIGH = new NullSafeComparator(false);
+	@SuppressWarnings("rawtypes")
-
+	public static final NullSafeComparator NULLS_HIGH = new NullSafeComparator<Object>(false);
 
 	private final Comparator<T> nonNullComparator;
 
@@ -63,7 +64,7 @@ public class NullSafeComparator<T> implements Comparator<T> {
 	 * @see #NULLS_LOW
 	 * @see #NULLS_HIGH
 	 */
-	@SuppressWarnings("unchecked")
+	@SuppressWarnings({ "unchecked", "rawtypes" })
 	private NullSafeComparator(boolean nullsLow) {
 		this.nonNullComparator = new ComparableComparator();
 		this.nullsLow = nullsLow;
@@ -99,6 +100,7 @@ public class NullSafeComparator<T> implements Comparator<T> {
 	}
 
 	@Override
+	@SuppressWarnings("unchecked")
 	public boolean equals(Object obj) {
 		if (this == obj) {
 			return true;
@@ -106,7 +108,7 @@ public class NullSafeComparator<T> implements Comparator<T> {
 		if (!(obj instanceof NullSafeComparator)) {
 			return false;
 		}
-		NullSafeComparator other = (NullSafeComparator) obj;
+		NullSafeComparator<T> other = (NullSafeComparator<T>) obj;
 		return (this.nonNullComparator.equals(other.nonNullComparator) && this.nullsLow == other.nullsLow);
 	}
 

spring-web/src/main/java/org/springframework/http/MediaType.java

@@ -814,10 +814,8 @@ public class MediaType implements Comparable<MediaType> {
 	public static void sortBySpecificityAndQuality(List<MediaType> mediaTypes) {
 		Assert.notNull(mediaTypes, "'mediaTypes' must not be null");
 		if (mediaTypes.size() > 1) {
-			Comparator<?>[] comparators = new Comparator[2];
+			Collections.sort(mediaTypes, new CompoundComparator<MediaType>(
-			comparators[0] = MediaType.SPECIFICITY_COMPARATOR;
+					MediaType.SPECIFICITY_COMPARATOR, MediaType.QUALITY_VALUE_COMPARATOR));
-			comparators[1] = MediaType.QUALITY_VALUE_COMPARATOR;
-			Collections.sort(mediaTypes, new CompoundComparator<MediaType>(comparators));
 		}
 	}