Cleanup redundant allocations and code around Comparator use

lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/GeneratingSuggester.java

@@ -61,8 +61,7 @@ List<String> suggest(String word, WordCase originalCase, Set<Suggestion> prevSug
 
   private List<Weighted<Root<String>>> findSimilarDictionaryEntries(
       String word, WordCase originalCase) {
-    Comparator<Weighted<Root<String>>> natural = Comparator.naturalOrder();
-    PriorityQueue<Weighted<Root<String>>> roots = new PriorityQueue<>(natural.reversed());
+    PriorityQueue<Weighted<Root<String>>> roots = new PriorityQueue<>(Comparator.reverseOrder());
 
     char[] excludeFlags = dictionary.allNonSuggestibleFlags();
     FlagEnumerator.Lookup flagLookup = dictionary.flagLookup;

lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java

@@ -17,8 +17,6 @@
 package org.apache.lucene.analysis.hunspell;
 
 import java.io.IOException;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 import org.apache.lucene.analysis.TokenFilter;
 import org.apache.lucene.analysis.TokenStream;
@@ -117,7 +115,16 @@ public boolean incrementToken() throws IOException {
     }
 
     if (longestOnly && buffer.size() > 1) {
-      Collections.sort(buffer, lengthComparator);
+      buffer.sort(
+          (o1, o2) -> {
+            int cmp = Integer.compare(o2.length, o1.length);
+            if (cmp == 0) {
+              // tie break on text
+              return o2.compareTo(o1);
+            } else {
+              return cmp;
+            }
+          });
     }
 
     CharsRef stem = buffer.remove(0);
@@ -139,18 +146,4 @@ public void reset() throws IOException {
     super.reset();
     buffer = null;
   }
-
-  static final Comparator<CharsRef> lengthComparator =
-      new Comparator<CharsRef>() {
-        @Override
-        public int compare(CharsRef o1, CharsRef o2) {
-          int cmp = Integer.compare(o2.length, o1.length);
-          if (cmp == 0) {
-            // tie break on text
-            return o2.compareTo(o1);
-          } else {
-            return cmp;
-          }
-        }
-      };
 }

lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/FingerprintFilter.java

@@ -18,7 +18,6 @@
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Comparator;
 import org.apache.lucene.analysis.CharArraySet;
 import org.apache.lucene.analysis.TokenFilter;
 import org.apache.lucene.analysis.TokenStream;
@@ -147,26 +146,23 @@ private final boolean buildSingleOutputToken() throws IOException {
 
     Arrays.sort(
         items,
-        new Comparator<Object>() {
-          @Override
-          public int compare(Object o1, Object o2) {
-            char[] v1 = (char[]) o1;
-            char[] v2 = (char[]) o2;
-            int len1 = v1.length;
-            int len2 = v2.length;
-            int lim = Math.min(len1, len2);
-
-            int k = 0;
-            while (k < lim) {
-              char c1 = v1[k];
-              char c2 = v2[k];
-              if (c1 != c2) {
-                return c1 - c2;
-              }
-              k++;
+        (o1, o2) -> {
+          char[] v1 = (char[]) o1;
+          char[] v2 = (char[]) o2;
+          int len1 = v1.length;
+          int len2 = v2.length;
+          int lim = Math.min(len1, len2);
+
+          int k = 0;
+          while (k < lim) {
+            char c1 = v1[k];
+            char c2 = v2[k];
+            if (c1 != c2) {
+              return c1 - c2;
             }
-            return len1 - len2;
+            k++;
           }
+          return len1 - len2;
         });
 
     // TODO lets append directly to termAttribute?

lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/dict/UserDictionary.java

@@ -20,8 +20,6 @@
 import java.io.IOException;
 import java.io.Reader;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 import java.util.regex.Pattern;
 import org.apache.lucene.analysis.morph.Dictionary;
@@ -83,14 +81,7 @@ private UserDictionary(List<String[]> featureEntries) throws IOException {
     // TODO: should we allow multiple segmentations per input 'phrase'?
     // the old treemap didn't support this either, and i'm not sure if it's needed/useful?
 
-    Collections.sort(
-        featureEntries,
-        new Comparator<String[]>() {
-          @Override
-          public int compare(String[] left, String[] right) {
-            return left[0].compareTo(right[0]);
-          }
-        });
+    featureEntries.sort((left, right) -> left[0].compareTo(right[0]));
 
     List<String> data = new ArrayList<>(featureEntries.size());
     List<int[]> segmentations = new ArrayList<>(featureEntries.size());

lucene/core/src/java/org/apache/lucene/codecs/CompetitiveImpactAccumulator.java

@@ -18,7 +18,6 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 import java.util.TreeSet;
@@ -39,20 +38,17 @@ public final class CompetitiveImpactAccumulator {
   /** Sole constructor. */
   public CompetitiveImpactAccumulator() {
     maxFreqs = new int[256];
-    Comparator<Impact> comparator =
-        new Comparator<Impact>() {
-          @Override
-          public int compare(Impact o1, Impact o2) {
-            // greater freqs compare greater
-            int cmp = Integer.compare(o1.freq, o2.freq);
-            if (cmp == 0) {
-              // greater norms compare lower
-              cmp = Long.compareUnsigned(o2.norm, o1.norm);
-            }
-            return cmp;
-          }
-        };
-    otherFreqNormPairs = new TreeSet<>(comparator);
+    otherFreqNormPairs =
+        new TreeSet<>(
+            (o1, o2) -> {
+              // greater freqs compare greater
+              int cmp = Integer.compare(o1.freq, o2.freq);
+              if (cmp == 0) {
+                // greater norms compare lower
+                cmp = Long.compareUnsigned(o2.norm, o1.norm);
+              }
+              return cmp;
+            });
   }
 
   /** Reset to the same state it was in after creation. */

lucene/core/src/java/org/apache/lucene/document/BinaryPoint.java

@@ -17,7 +17,6 @@
 package org.apache.lucene.document;
 
 import java.util.Arrays;
-import java.util.Comparator;
 import org.apache.lucene.index.IndexableFieldType;
 import org.apache.lucene.index.PointValues;
 import org.apache.lucene.search.MatchNoDocsQuery;
@@ -238,14 +237,7 @@ public static Query newSetQuery(String field, byte[]... values) {
 
     // Don't unexpectedly change the user's incoming values array:
     byte[][] sortedValues = values.clone();
-    Arrays.sort(
-        sortedValues,
-        new Comparator<byte[]>() {
-          @Override
-          public int compare(byte[] a, byte[] b) {
-            return Arrays.compareUnsigned(a, 0, a.length, b, 0, b.length);
-          }
-        });
+    Arrays.sort(sortedValues, (a, b) -> Arrays.compareUnsigned(a, 0, a.length, b, 0, b.length));
 
     final BytesRef encoded = new BytesRef(new byte[bytesPerDim]);
 

lucene/core/src/java/org/apache/lucene/document/InetAddressPoint.java

@@ -19,7 +19,6 @@
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.Arrays;
-import java.util.Comparator;
 import org.apache.lucene.index.PointValues;
 import org.apache.lucene.search.PointInSetQuery;
 import org.apache.lucene.search.PointRangeQuery;
@@ -288,14 +287,7 @@ public static Query newSetQuery(String field, InetAddress... values) {
       sortedValues[i] = encode(values[i]);
     }
 
-    Arrays.sort(
-        sortedValues,
-        new Comparator<byte[]>() {
-          @Override
-          public int compare(byte[] a, byte[] b) {
-            return Arrays.compareUnsigned(a, 0, BYTES, b, 0, BYTES);
-          }
-        });
+    Arrays.sort(sortedValues, (a, b) -> Arrays.compareUnsigned(a, 0, BYTES, b, 0, BYTES));
 
     final BytesRef encoded = new BytesRef(new byte[BYTES]);
 

lucene/core/src/java/org/apache/lucene/document/NearestNeighbor.java

@@ -20,7 +20,6 @@
 import static org.apache.lucene.geo.GeoEncodingUtils.decodeLongitude;
 
 import java.io.IOException;
-import java.util.Comparator;
 import java.util.List;
 import java.util.PriorityQueue;
 import org.apache.lucene.geo.Rectangle;
@@ -240,18 +239,15 @@ public static NearestHit[] nearest(
     final PriorityQueue<NearestHit> hitQueue =
         new PriorityQueue<>(
             n,
-            new Comparator<NearestHit>() {
-              @Override
-              public int compare(NearestHit a, NearestHit b) {
-                // sort by opposite distanceSortKey natural order
-                int cmp = Double.compare(a.distanceSortKey, b.distanceSortKey);
-                if (cmp != 0) {
-                  return -cmp;
-                }
-
-                // tie-break by higher docID:
-                return b.docID - a.docID;
+            (a, b) -> {
+              // sort by opposite distanceSortKey natural order
+              int cmp = Double.compare(a.distanceSortKey, b.distanceSortKey);
+              if (cmp != 0) {
+                return -cmp;
               }
+
+              // tie-break by higher docID:
+              return b.docID - a.docID;
             });
 
     // Holds all cells, sorted by closest to the point:

lucene/core/src/java/org/apache/lucene/index/MultiTermsEnum.java

@@ -18,7 +18,6 @@
 
 import java.io.IOException;
 import java.util.Arrays;
-import java.util.Comparator;
 import org.apache.lucene.util.ArrayUtil;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.BytesRefBuilder;
@@ -32,14 +31,6 @@
  */
 public final class MultiTermsEnum extends BaseTermsEnum {
 
-  private static final Comparator<TermsEnumWithSlice> INDEX_COMPARATOR =
-      new Comparator<TermsEnumWithSlice>() {
-        @Override
-        public int compare(TermsEnumWithSlice o1, TermsEnumWithSlice o2) {
-          return o1.subIndex - o2.subIndex;
-        }
-      };
-
   private final TermMergeQueue queue;
   // all of our subs (one per sub-reader)
   private final TermsEnumWithSlice[] subs;
@@ -338,7 +329,7 @@ public PostingsEnum postings(PostingsEnum reuse, int flags) throws IOException {
 
     int upto = 0;
 
-    ArrayUtil.timSort(top, 0, numTop, INDEX_COMPARATOR);
+    ArrayUtil.timSort(top, 0, numTop, (o1, o2) -> o1.subIndex - o2.subIndex);
 
     for (int i = 0; i < numTop; i++) {
 

lucene/core/src/java/org/apache/lucene/search/DisjunctionScoreBlockBoundaryPropagator.java

@@ -40,7 +40,7 @@ final class DisjunctionScoreBlockBoundaryPropagator {
                   throw new RuntimeException(e);
                 }
               })
-          .thenComparing(Comparator.comparing(s -> s.iterator().cost()));
+          .thenComparing(s -> s.iterator().cost());
 
   private final Scorer[] scorers;
   private final float[] maxScores;

lucene/core/src/java/org/apache/lucene/search/QueryRescorer.java

@@ -50,14 +50,7 @@ public TopDocs rescore(IndexSearcher searcher, TopDocs firstPassTopDocs, int top
       throws IOException {
     ScoreDoc[] hits = firstPassTopDocs.scoreDocs.clone();
 
-    Arrays.sort(
-        hits,
-        new Comparator<ScoreDoc>() {
-          @Override
-          public int compare(ScoreDoc a, ScoreDoc b) {
-            return a.doc - b.doc;
-          }
-        });
+    Arrays.sort(hits, (a, b) -> a.doc - b.doc);
 
     List<LeafReaderContext> leaves = searcher.getIndexReader().leaves();
 
@@ -111,19 +104,16 @@ public int compare(ScoreDoc a, ScoreDoc b) {
     }
 
     Comparator<ScoreDoc> sortDocComparator =
-        new Comparator<ScoreDoc>() {
-          @Override
-          public int compare(ScoreDoc a, ScoreDoc b) {
-            // Sort by score descending, then docID ascending:
-            if (a.score > b.score) {
-              return -1;
-            } else if (a.score < b.score) {
-              return 1;
-            } else {
-              // This subtraction can't overflow int
-              // because docIDs are >= 0:
-              return a.doc - b.doc;
-            }
+        (a, b) -> {
+          // Sort by score descending, then docID ascending:
+          if (a.score > b.score) {
+            return -1;
+          } else if (a.score < b.score) {
+            return 1;
+          } else {
+            // This subtraction can't overflow int
+            // because docIDs are >= 0:
+            return a.doc - b.doc;
           }
         };
 

lucene/core/src/java/org/apache/lucene/search/TopTermsRewrite.java

@@ -17,7 +17,6 @@
 package org.apache.lucene.search;
 
 import java.io.IOException;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.PriorityQueue;
@@ -160,7 +159,7 @@ public boolean collect(BytesRef bytes) throws IOException {
 
     final B b = getTopLevelBuilder();
     final ScoreTerm[] scoreTerms = stQueue.toArray(new ScoreTerm[stQueue.size()]);
-    ArrayUtil.timSort(scoreTerms, scoreTermSortByTermComp);
+    ArrayUtil.timSort(scoreTerms, (st1, st2) -> st1.bytes.get().compareTo(st2.bytes.get()));
 
     for (final ScoreTerm st : scoreTerms) {
       final Term term = new Term(query.field, st.bytes.toBytesRef());
@@ -188,14 +187,6 @@ public boolean equals(Object obj) {
     return true;
   }
 
-  private static final Comparator<ScoreTerm> scoreTermSortByTermComp =
-      new Comparator<ScoreTerm>() {
-        @Override
-        public int compare(ScoreTerm st1, ScoreTerm st2) {
-          return st1.bytes.get().compareTo(st2.bytes.get());
-        }
-      };
-
   static final class ScoreTerm implements Comparable<ScoreTerm> {
     public final BytesRefBuilder bytes = new BytesRefBuilder();
     public float boost;

lucene/core/src/java/org/apache/lucene/util/Accountables.java

@@ -19,7 +19,6 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 
@@ -98,14 +97,7 @@ public static Collection<Accountable> namedAccountables(
     for (Map.Entry<?, ? extends Accountable> kv : in.entrySet()) {
       resources.add(namedAccountable(prefix + " '" + kv.getKey() + "'", kv.getValue()));
     }
-    Collections.sort(
-        resources,
-        new Comparator<Accountable>() {
-          @Override
-          public int compare(Accountable o1, Accountable o2) {
-            return o1.toString().compareTo(o2.toString());
-          }
-        });
+    resources.sort((o1, o2) -> o1.toString().compareTo(o2.toString()));
     return Collections.unmodifiableList(resources);
   }