[#260] count(Predicate)

src/main/java/one/util/streamex/AbstractStreamEx.java

@@ -536,6 +536,23 @@ public long count() {
  return stream().count();
  }
 
+ /**
+ * Counts the number of elements in the stream that satisfy the predicate.
+ *
+ * <p>
+ * This is a terminal operation.
+ *
+ * @param predicate a <a
+ * href="package-summary.html#NonInterference">non-interfering </a>,
+ * <a href="package-summary.html#Statelessness">stateless</a>
+ * predicate to apply to stream elements. Only elements passing
+ * the predicate will be counted.
+ * @return the count of elements in this stream satisfying the predicate.
+ */
+ public long count(Predicate<? super T> predicate) {
+ return filter(predicate).count();
+ }
+
  @Override
  public boolean anyMatch(Predicate<? super T> predicate) {
  if (context.fjp != null)

src/main/java/one/util/streamex/DoubleStreamEx.java

@@ -1134,6 +1134,23 @@ public long count() {
  return stream().count();
  }
 
+ /**
+ * Counts the number of elements in the stream that satisfy the predicate.
+ *
+ * <p>
+ * This is a terminal operation.
+ *
+ * @param predicate a <a
+ * href="package-summary.html#NonInterference">non-interfering </a>,
+ * <a href="package-summary.html#Statelessness">stateless</a>
+ * predicate to apply to stream elements. Only elements passing
+ * the predicate will be counted.
+ * @return the count of elements in this stream satisfying the predicate.
+ */
+ public long count(DoublePredicate predicate) {
+ return filter(predicate).count();
+ }
+
  @Override
  public OptionalDouble average() {
  if (context.fjp != null)

src/main/java/one/util/streamex/IntStreamEx.java

@@ -1246,6 +1246,23 @@ public long count() {
  return stream().count();
  }
 
+ /**
+ * Counts the number of elements in the stream that satisfy the predicate.
+ *
+ * <p>
+ * This is a terminal operation.
+ *
+ * @param predicate a <a
+ * href="package-summary.html#NonInterference">non-interfering </a>,
+ * <a href="package-summary.html#Statelessness">stateless</a>
+ * predicate to apply to stream elements. Only elements passing
+ * the predicate will be counted.
+ * @return the count of elements in this stream satisfying the predicate.
+ */
+ public long count(IntPredicate predicate) {
+ return filter(predicate).count();
+ }
+
  @Override
  public OptionalDouble average() {
  if (context.fjp != null)

src/main/java/one/util/streamex/LongStreamEx.java

@@ -1167,6 +1167,23 @@ public long count() {
  return stream().count();
  }
 
+ /**
+ * Counts the number of elements in the stream that satisfy the predicate.
+ *
+ * <p>
+ * This is a terminal operation.
+ *
+ * @param predicate a <a
+ * href="package-summary.html#NonInterference">non-interfering </a>,
+ * <a href="package-summary.html#Statelessness">stateless</a>
+ * predicate to apply to stream elements. Only elements passing
+ * the predicate will be counted.
+ * @return the count of elements in this stream satisfying the predicate.
+ */
+ public long count(LongPredicate predicate) {
+ return filter(predicate).count();
+ }
+
  @Override
  public OptionalDouble average() {
  if (context.fjp != null)

src/test/java/one/util/streamex/api/DoubleStreamExTest.java

@@ -539,4 +539,9 @@ public void testIntersperse() {
  .toArray(), 0.0);
  assertEquals(0L, IntStreamEx.empty().intersperse(1).count());
  }
+
+ @Test
+ public void testCount() {
+ assertEquals(5L, DoubleStreamEx.of(0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4).count(x -> x == (int) x));
+ }
 }

src/test/java/one/util/streamex/api/IntStreamExTest.java

@@ -15,6 +15,12 @@
  */
 package one.util.streamex.api;
 
+import one.util.streamex.IntStreamEx;
+import one.util.streamex.StreamEx;
+import org.junit.FixMethodOrder;
+import org.junit.Test;
+import org.junit.runners.MethodSorters;
+
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -47,13 +53,6 @@
 import java.util.stream.IntStream;
 import java.util.stream.IntStream.Builder;
 
-import org.junit.FixMethodOrder;
-import org.junit.Test;
-import org.junit.runners.MethodSorters;
-
-import one.util.streamex.IntStreamEx;
-import one.util.streamex.StreamEx;
-
 import static one.util.streamex.TestHelpers.checkSpliterator;
 import static one.util.streamex.TestHelpers.intStreamEx;
 import static one.util.streamex.TestHelpers.streamEx;
@@ -802,4 +801,9 @@ public void testIntersperse() {
  .toArray());
  assertEquals(0L, IntStreamEx.empty().intersperse(1).count());
  }
+
+ @Test
+ public void testCount() {
+ assertEquals(5L, IntStreamEx.range(10).count(x -> x % 2 == 0));
+ }
 }

src/test/java/one/util/streamex/api/LongStreamExTest.java

@@ -15,6 +15,13 @@
  */
 package one.util.streamex.api;
 
+import one.util.streamex.IntStreamEx;
+import one.util.streamex.LongStreamEx;
+import one.util.streamex.StreamEx;
+import org.junit.FixMethodOrder;
+import org.junit.Test;
+import org.junit.runners.MethodSorters;
+
 import java.nio.LongBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -42,14 +49,6 @@
 import java.util.stream.LongStream;
 import java.util.stream.LongStream.Builder;
 
-import org.junit.FixMethodOrder;
-import org.junit.Test;
-import org.junit.runners.MethodSorters;
-
-import one.util.streamex.IntStreamEx;
-import one.util.streamex.LongStreamEx;
-import one.util.streamex.StreamEx;
-
 import static one.util.streamex.TestHelpers.checkSpliterator;
 import static one.util.streamex.TestHelpers.longStreamEx;
 import static one.util.streamex.TestHelpers.streamEx;
@@ -633,4 +632,9 @@ public void testIntersperse() {
  LongStreamEx.of(1, 10, 100, 1000).intersperse(0).toArray());
  assertEquals(0L, IntStreamEx.empty().intersperse(1).count());
  }
+
+ @Test
+ public void testCount() {
+ assertEquals(5L, LongStreamEx.range(10).count(x -> x % 2 == 0));
+ }
 }

src/test/java/one/util/streamex/api/StreamExTest.java

@@ -21,7 +21,6 @@
 import one.util.streamex.MoreCollectors;
 import one.util.streamex.StreamEx;
 import one.util.streamex.TestHelpers.Point;
-
 import org.junit.FixMethodOrder;
 import org.junit.Rule;
 import org.junit.Test;
@@ -2298,4 +2297,9 @@ public void testReduceWithZero() {
  assertEquals((Integer) 0, s.get().reduceWithZero(0, 1, (a, b) -> a * b));
  });
  }
+
+ @Test
+ public void testCount() {
+ assertEquals(3L, StreamEx.of("x", "", "y", "", "z").count(x -> !x.isEmpty()));
+ }
 }

wiki/CHANGES.md

@@ -2,6 +2,9 @@
 
 Check also [MIGRATION.md](MIGRATION.md) for possible compatibility problems.
 
+### 0.8.2
+* [#260] Added: `count(Predicate)`
+
 ### 0.8.1
 * [#245] Fixed: back to 'jar' packaging
 * [#253] Added: Version information in module descriptor