Merge pull request #6629 from sushant57/master

Guide to Guava Multiset

guava-collections-set/.gitignore

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+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear

guava-collections-set/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>guava-collections-set</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>guava-collections-set</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>guava-collections-set</finalName>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <guava.version>27.1-jre</guava.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>

guava-collections-set/src/test/java/org/baeldung/guava/GuavaMultiSetUnitTest.java

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+package org.baeldung.guava;
+
+import com.google.common.collect.HashMultiset;
+import com.google.common.collect.Multiset;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class GuavaMultiSetUnitTest {
+
+    @Test
+    public void givenMultiSet_whenAddingValues_shouldReturnCorrectCount() {
+        Multiset<String> bookStore = HashMultiset.create();
+        bookStore.add("Potter");
+        bookStore.add("Potter");
+        bookStore.add("Potter");
+
+        assertThat(bookStore.contains("Potter")).isTrue();
+        assertThat(bookStore.count("Potter")).isEqualTo(3);
+    }
+
+    @Test
+    public void givenMultiSet_whenRemovingValues_shouldReturnCorrectCount() {
+        Multiset<String> bookStore = HashMultiset.create();
+        bookStore.add("Potter");
+        bookStore.add("Potter");
+
+        bookStore.remove("Potter");
+        assertThat(bookStore.contains("Potter")).isTrue();
+        assertThat(bookStore.count("Potter")).isEqualTo(1);
+    }
+
+    @Test
+    public void givenMultiSet_whenSetCount_shouldReturnCorrectCount() {
+        Multiset<String> bookStore = HashMultiset.create();
+        bookStore.setCount("Potter", 50);
+        assertThat(bookStore.count("Potter")).isEqualTo(50);
+    }
+
+    @Test
+    public void givenMultiSet_whenSettingNegativeCount_shouldThrowException() {
+        Multiset<String> bookStore = HashMultiset.create();
+        assertThatThrownBy(() -> bookStore.setCount("Potter", -1))
+          .isInstanceOf(IllegalArgumentException.class);
+    }
+
+    @Test
+    public void givenMultiSet_whenSettingCountWithEmptySet_shouldBeSuccessful() {
+        Multiset<String> bookStore = HashMultiset.create();
+        assertThat(bookStore.setCount("Potter", 0, 2)).isTrue();
+    }
+
+    @Test
+    public void givenMultiSet_whenSettingCountWithCorrectValue_shouldBeSuccessful() {
+        Multiset<String> bookStore = HashMultiset.create();
+        bookStore.add("Potter");
+        bookStore.add("Potter");
+
+        assertThat(bookStore.setCount("Potter", 2, 52)).isTrue();
+    }
+
+    @Test
+    public void givenMultiSet_whenSettingCountWithIncorrectValue_shouldFail() {
+        Multiset<String> bookStore = HashMultiset.create();
+        bookStore.add("Potter");
+        bookStore.add("Potter");
+
+        assertThat(bookStore.setCount("Potter", 5, 52)).isFalse();
+    }
+
+    @Test
+    public void givenMap_compareMultiSetOperations() {
+        Map<String, Integer> bookStore = new HashMap<>();
+        bookStore.put("Potter", 3);
+
+        assertThat(bookStore.containsKey("Potter")).isTrue();
+        assertThat(bookStore.get("Potter")).isEqualTo(3);
+
+        bookStore.put("Potter", 2);
+        assertThat(bookStore.get("Potter")).isEqualTo(2);
+
+        bookStore.put("Potter", null);
+        assertThat(bookStore.containsKey("Potter")).isTrue();
+
+        bookStore.put("Potter", -1);
+        assertThat(bookStore.containsKey("Potter")).isTrue();
+    }
+}