[BAEL-1775] Getting size of Iterable in Java

2018-05-20 01:07:00 +05:30
parent a6c5f89093
commit fa77261c42
2 changed files with 124 additions and 0 deletions
@@ -0,0 +1,65 @@
+package com.baeldung.java.iterable;
+
+import java.util.Collection;
+import java.util.stream.StreamSupport;
+
+import org.apache.commons.collections4.IterableUtils;
+
+import com.google.common.collect.Iterables;
+
+/**
+ * Provides methods for getting the size of an {@link Iterable} object.
+ */
+public class IterableSize {
+
+    /**
+     * Get the size of {@code Iterable} using Java 7.
+     *
+     * @param data the iterable
+     * @return the size of the iterable
+     */
+    public static int sizeUsingJava7(final Iterable data) {
+
+        if (data instanceof Collection) {
+            return ((Collection<?>) data).size();
+        }
+        int counter = 0;
+        for (final Object i : data) {
+            counter++;
+        }
+        return counter;
+    }
+
+    /**
+     * Get the size of {@code Iterable} using Java 8.
+     *
+     * @param data the iterable
+     * @return the size of the iterable
+     */
+    public static long sizeUsingJava8(final Iterable data) {
+
+        return StreamSupport.stream(data.spliterator(), false).count();
+    }
+
+    /**
+     * Get the size of {@code Iterable} using Apache Collections.
+     *
+     * @param data the iterable
+     * @return the size of the iterable
+     */
+    public static int sizeUsingApacheCollections(final Iterable data) {
+
+        return IterableUtils.size(data);
+    }
+
+    /**
+     * Get the size of {@code Iterable} using Google Guava.
+     *
+     * @param data the iterable
+     * @return the size of the iterable
+     */
+    public static int sizeUsingGoogleGuava(final Iterable data) {
+
+        return Iterables.size(data);
+    }
+}