Fix ArrayOfStringsSummary and add .mvn to root.

.gitignore

@@ -15,6 +15,7 @@
 
 # Additional tools
 .clover/
+.mvn/
 
 # OSX files
 **/.DS_Store

.mvn/maven.config

@@ -0,0 +1,6 @@
+# suppresses the warning:
+# Direct modification of testCompileSourceRoots through add() is deprecated and will not work in Maven 4.0.0. Please use the add/remove methods instead. 
+# If you're using a plugin that causes this warning, please upgrade to the latest version and report an issue if the warning persists. 
+# To disable these warnings, set -Dmaven.project.sourceRoots.warningsDisabled=true on the command line, in the .mvn/maven.config file, 
+# or in project POM properties.
+-Dmaven.project.sourceRoots.warningsDisabled=true

src/main/java/org/apache/datasketches/tuple/strings/ArrayOfStringsSummary.java

@@ -36,19 +36,16 @@
  */
 public final class ArrayOfStringsSummary implements UpdatableSummary<String[]> {
 
-  private String[] stringArr = null;
+  private String[] stringArr = new String[] {}; //empty string array;
 
   /**
    * No argument constructor.
    */
-  ArrayOfStringsSummary() { //required for ArrayOfStringsSummaryFactory
-    stringArr = null;
-  }
+  ArrayOfStringsSummary() {} //required for ArrayOfStringsSummaryFactory
 
   //Used by copy() and in test
   ArrayOfStringsSummary(final String[] stringArr) {
-    this.stringArr = stringArr.clone();
-    checkNumNodes(stringArr.length);
+    update(stringArr);
   }
 
   //used by fromMemorySegment and in test
@@ -87,10 +84,20 @@ public final class ArrayOfStringsSummary implements UpdatableSummary<String[]> {
     this.stringArr = stringArr;
   }
 
+  //From UpdatableSummary
+
+  @Override
+  public final ArrayOfStringsSummary update(final String[] value) {
+      if (value == null) { stringArr = new String[] {}; }
+      else { stringArr = value.clone(); }
+    return this;
+  }
+
+  //From Summary
+
   @Override
   public ArrayOfStringsSummary copy() {
-    final ArrayOfStringsSummary nodes = new ArrayOfStringsSummary(stringArr);
-    return nodes;
+    return new ArrayOfStringsSummary(stringArr);
   }
 
   @Override
@@ -112,16 +119,6 @@ public byte[] toByteArray() {
     return out;
   }
 
-  //From UpdatableSummary
-
-  @Override
-  public ArrayOfStringsSummary update(final String[] value) {
-    if (stringArr == null) {
-      stringArr = value.clone();
-    }
-    return this;
-  }
-
   //From Object
 
   @Override
@@ -139,6 +136,8 @@ public boolean equals(final Object summary) {
     return thisStr.equals(thatStr);
   }
 
+  //Local
+
   /**
    * Returns the nodes array for this summary.
    * @return the nodes array for this summary.

src/test/java/org/apache/datasketches/tuple/strings/ArrayOfStringsSketchTest.java

@@ -49,40 +49,52 @@ public void checkSketch() {
     for (int i = 0; i < len; i++) {
       sketch1.update(strArrArr[i], strArrArr[i]);
     }
+    println("Sketch1");
+    printSummaries(sketch1.iterator());
+
     sketch1.update(strArrArr[0], strArrArr[0]); //insert duplicate
+    println("Sketch1 updated with a duplicate");
     printSummaries(sketch1.iterator());
-    byte[] array = sketch1.toByteArray();
-    MemorySegment wseg = MemorySegment.ofArray(array);
+
+    MemorySegment wseg = MemorySegment.ofArray(sketch1.toByteArray());
     ArrayOfStringsTupleSketch sketch2 = new ArrayOfStringsTupleSketch(wseg);
+    println("Sketch2 = Sketch1 via SerDe");
     printSummaries(sketch2.iterator());
-    checkSummaries(sketch2, sketch2);
+    checkSummariesEqual(sketch2, sketch2);
 
     String[] strArr3 = {"g", "h" };
     sketch2.update(strArr3, strArr3);
-
+    println("Sketch2 with a new row");
+    printSummaries(sketch2.iterator());
+
     TupleUnion<ArrayOfStringsSummary> union = new TupleUnion<>(new ArrayOfStringsSummarySetOperations());
     union.union(sketch1);
     union.union(sketch2);
     CompactTupleSketch<ArrayOfStringsSummary> csk = union.getResult();
-    //printSummaries(csk.iterator());
+    println("Result of union of Sketch1, Sketch2");
+    printSummaries(csk.iterator());
     assertEquals(csk.getRetainedEntries(), 4);
 
     TupleIntersection<ArrayOfStringsSummary> inter =
         new TupleIntersection<>(new ArrayOfStringsSummarySetOperations());
     inter.intersect(sketch1);
     inter.intersect(sketch2);
     csk = inter.getResult();
+    println("Intersect Sketch1, Sketch2");
+    printSummaries(csk.iterator());
     assertEquals(csk.getRetainedEntries(), 3);
 
     TupleAnotB<ArrayOfStringsSummary> aNotB =  new TupleAnotB<>();
     aNotB.setA(sketch2);
     aNotB.notB(sketch1);
     csk = aNotB.getResult(true);
+    println("AnotB(Sketch2, Sketch1)");
+    printSummaries(csk.iterator());
     assertEquals(csk.getRetainedEntries(), 1);
 
   }
 
-  private static void checkSummaries(ArrayOfStringsTupleSketch sk1, ArrayOfStringsTupleSketch sk2) {
+  private static void checkSummariesEqual(ArrayOfStringsTupleSketch sk1, ArrayOfStringsTupleSketch sk2) {
     TupleSketchIterator<ArrayOfStringsSummary> it1 = sk1.iterator();
     TupleSketchIterator<ArrayOfStringsSummary> it2 = sk2.iterator();
     while(it1.next() && it2.next()) {
@@ -100,6 +112,7 @@ static void printSummaries(TupleSketchIterator<ArrayOfStringsSummary> it) {
       }
       println("");
     }
+    println("");
   }
 
   @Test

src/test/java/org/apache/datasketches/tuple/strings/ArrayOfStringsSummary_Issue699.java

@@ -0,0 +1,88 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.datasketches.tuple.strings;
+
+import static org.apache.datasketches.common.Util.LS;
+
+import org.apache.datasketches.theta.UpdatableThetaSketch;
+import org.apache.datasketches.tuple.TupleSketchIterator;
+import org.apache.datasketches.tuple.TupleUnion;
+import org.testng.annotations.Test;
+
+public class ArrayOfStringsSummary_Issue699 {
+  UpdatableThetaSketch thetaSk = UpdatableThetaSketch.builder().build();
+  ArrayOfStringsTupleSketch tupleSk = new ArrayOfStringsTupleSketch();
+  TupleUnion<ArrayOfStringsSummary> union = new TupleUnion<>(new ArrayOfStringsSummarySetOperations());
+
+  @Test
+  void go() {
+    thetaSk.update("a");
+    thetaSk.update("b");
+    thetaSk.update("c");
+
+    tupleSk.update("a", new String[] {"x", "y"});
+    tupleSk.update("b", new String[] {"z"});
+    tupleSk.update("e", new String[] {"x", "z"});
+
+    println("Print Tuple Summary before union");
+    printSummaries(tupleSk.iterator());
+
+    union.union(tupleSk);
+    union.union(thetaSk, new ArrayOfStringsSummary()); //enable this or the next
+    //union.union(thetaSk, new ArrayOfStringsSummary(new String[] {"u", "v"})); //optional association
+
+    println("Print Tuple Summary after union");
+    printSummaries(union.getResult().iterator());
+  }
+
+  @Test
+  void checkCopy() {
+    ArrayOfStringsSummary aoss = new ArrayOfStringsSummary();
+    aoss.copy(); //if null this will throw
+  }
+
+  @Test
+  void checkToByteArray() {
+    ArrayOfStringsSummary aoss = new ArrayOfStringsSummary();
+    byte[] bytes = aoss.toByteArray();
+    println("byte[].length = " + bytes.length);
+  }
+
+
+  static void printSummaries(TupleSketchIterator<ArrayOfStringsSummary> it) {
+    while (it.next()) {
+      String[] strArr = it.getSummary().getValue();
+      if (strArr.length == 0) { print("-"); } //illustrates an empty string array
+      for (String s : strArr) {
+        print(s + ", ");
+      }
+      println("");
+    }
+    println("");
+  }
+
+  private static void println(Object o) { 
+    print(o + LS);
+  }
+
+  private static void print(Object o) {
+    //System.out.print(o.toString());
+  }
+}