Check-in commons-math 3.6.1 am: 1354beaf45 am: 0018f64b87 am: b3715644fb

Original change: https://android-review.googlesource.com/c/platform/external/apache-commons-math/+/2702413

Change-Id: I5ad9b2a0822d668b5b6a62933c6d4c1f0b802001
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/src/main/java/org/apache/commons/math3/fraction/FractionField.java b/src/main/java/org/apache/commons/math3/fraction/FractionField.java
new file mode 100644
index 0000000..bc00716
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/fraction/FractionField.java
@@ -0,0 +1,87 @@
+/*
+ * 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.commons.math3.fraction;
+
+import org.apache.commons.math3.Field;
+import org.apache.commons.math3.FieldElement;
+
+import java.io.Serializable;
+
+/**
+ * Representation of the fractional numbers field.
+ *
+ * <p>This class is a singleton.
+ *
+ * @see Fraction
+ * @since 2.0
+ */
+public class FractionField implements Field<Fraction>, Serializable {
+
+    /** Serializable version identifier */
+    private static final long serialVersionUID = -1257768487499119313L;
+
+    /** Private constructor for the singleton. */
+    private FractionField() {}
+
+    /**
+     * Get the unique instance.
+     *
+     * @return the unique instance
+     */
+    public static FractionField getInstance() {
+        return LazyHolder.INSTANCE;
+    }
+
+    /** {@inheritDoc} */
+    public Fraction getOne() {
+        return Fraction.ONE;
+    }
+
+    /** {@inheritDoc} */
+    public Fraction getZero() {
+        return Fraction.ZERO;
+    }
+
+    /** {@inheritDoc} */
+    public Class<? extends FieldElement<Fraction>> getRuntimeClass() {
+        return Fraction.class;
+    }
+
+    // CHECKSTYLE: stop HideUtilityClassConstructor
+    /**
+     * Holder for the instance.
+     *
+     * <p>We use here the Initialization On Demand Holder Idiom.
+     */
+    private static class LazyHolder {
+        /** Cached field instance. */
+        private static final FractionField INSTANCE = new FractionField();
+    }
+
+    // CHECKSTYLE: resume HideUtilityClassConstructor
+
+    /**
+     * Handle deserialization of the singleton.
+     *
+     * @return the singleton instance
+     */
+    private Object readResolve() {
+        // return the singleton instance
+        return LazyHolder.INSTANCE;
+    }
+}