DATACMNS-790 - Added Tuple value type.

Related pull request: https://github.com/spring-projects/spring-data-mongodb/pull/327.

src/main/java/org/springframework/data/util/Tuple.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed 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.springframework.data.util;
+
+import org.springframework.util.Assert;
+
+/**
+ * A tuple of things.
+ * 
+ * @author Tobias Trelle
+ * @author Oliver Gierke
+ * @param <T> Type of the first thing.
+ * @param <S> Type of the second thing.
+ * @since 1.12
+ */
+public final class Tuple<S, T> {
+
+	private final T second;
+	private final S first;
+
+	/**
+	 * Creates a new {@link Tuple} for the given elements.
+	 * 
+	 * @param first must not be {@literal null}.
+	 * @param second must not be {@literal null}.
+	 * @return
+	 */
+	Tuple(S first, T second) {
+
+		Assert.notNull(first, "First tuple element must not be null!");
+		Assert.notNull(second, "Second tuple element must not be null!");
+
+		this.second = second;
+		this.first = first;
+	}
+
+	/**
+	 * Creates a new {@link Tuple} for the given elements.
+	 * 
+	 * @param first must not be {@literal null}.
+	 * @param second must not be {@literal null}.
+	 * @return
+	 */
+	public static <S, T> Tuple<S, T> of(S first, T second) {
+		return new Tuple<S, T>(first, second);
+	}
+
+	/**
+	 * Returns the first element of the {@link com.querydsl.core.Tuple}.
+	 * 
+	 * @return
+	 */
+	public S getFirst() {
+		return first;
+	}
+
+	/**
+	 * Returns the second element of the {@link com.querydsl.core.Tuple}.
+	 * 
+	 * @return
+	 */
+	public T getSecond() {
+		return second;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+
+		if (this == obj) {
+			return true;
+		}
+
+		if (!(obj instanceof Tuple)) {
+			return false;
+		}
+
+		Tuple<?, ?> that = (Tuple<?, ?>) obj;
+
+		return this.first.equals(that.first) && this.second.equals(that.second);
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+
+		int result = 31;
+
+		result += 17 * first.hashCode();
+		result += 17 * second.hashCode();
+
+		return result;
+	}
+}

src/test/java/org/springframework/data/util/TupleUnitTests.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed 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.springframework.data.util;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+/**
+ * Unit tests for {@link Tuple}.
+ * 
+ * @author Oliver Gierke
+ */
+public class TupleUnitTests {
+
+	/**
+	 * @see DATACMNS-790
+	 */
+	@Test
+	public void setsUpSimpleInstance() {
+
+		Tuple<Integer, Integer> tuple = Tuple.of(1, 2);
+
+		assertThat(tuple.getFirst(), is(1));
+		assertThat(tuple.getSecond(), is(2));
+	}
+
+	/**
+	 * @see DATACMNS-790
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullFirstElement() {
+		Tuple.of(null, 1);
+	}
+
+	/**
+	 * @see DATACMNS-790
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullSecondElement() {
+		Tuple.of(1, null);
+	}
+
+	/**
+	 * @see DATACMNS-790
+	 */
+	@Test
+	public void hasCorrectEquals() {
+
+		Tuple<Integer, Integer> first = Tuple.of(1, 2);
+		Tuple<Integer, Integer> second = Tuple.of(1, 2);
+
+		assertThat(first, is(first));
+		assertThat(first, is(second));
+		assertThat(second, is(first));
+	}
+
+	/**
+	 * @see DATACMNS-790
+	 */
+	@Test
+	public void hasCorrectHashCode() {
+
+		Tuple<Integer, Integer> first = Tuple.of(1, 2);
+		Tuple<Integer, Integer> second = Tuple.of(1, 2);
+		Tuple<Integer, Integer> third = Tuple.of(2, 2);
+
+		assertThat(first.hashCode(), is(second.hashCode()));
+		assertThat(first.hashCode(), is(not(third.hashCode())));
+	}
+}