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Simple BiMap implementation
DEVSIX-2121
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  • commons/src

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‎commons/src/main/java/com/itextpdf/commons/datastructures/BiMap.java

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package com.itextpdf.commons.datastructures;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* A simple bi-directional map.
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*
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* @param <K> the type of the first key
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* @param <V> the type of the second key
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*/
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public final class BiMap<K, V> {
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private final Map<K, V> map = new HashMap<K, V>();
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private final Map<V, K> inverseMap = new HashMap<V, K>();
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/**
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* Creates a new {@link BiMap} instance.
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*/
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public BiMap() {
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// empty constructor
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}
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/**
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* Puts the entry into the map.
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* If the key already exists, the value will be overwritten.
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* If the value already exists, the key will be overwritten.
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* If both key and value already exist, the entry will be overwritten.
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* If neither key nor value already exist, the entry will be added.
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*
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* @param k the key
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* @param v the value
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*/
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public void put(K k, V v) {
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map.put(k, v);
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inverseMap.put(v, k);
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}
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/**
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* Gets the value by key.
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*
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* @param value the key
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*
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* @return the value
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*/
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public V getByKey(K value) {
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return map.get(value);
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}
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/**
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* Gets the key by value.
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*
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* @param key the value
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*
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* @return the key
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*/
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public K getByValue(V key) {
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return inverseMap.get(key);
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}
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/**
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* Removes the entry by key.
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*
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* @param k the key
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*/
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public void removeByKey(K k) {
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V v = map.remove(k);
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if (v != null) {
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inverseMap.remove(v);
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}
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}
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/**
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* Removes the entry by value.
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*
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* @param v the value
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*/
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public void removeByValue(V v) {
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K k = inverseMap.remove(v);
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if (k != null) {
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map.remove(k);
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}
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}
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/**
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* Gets the size of the map.
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*
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* @return the size of the map
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*/
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public int size() {
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return map.size();
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}
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/**
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* removes all entries from the map.
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*/
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public void clear() {
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map.clear();
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inverseMap.clear();
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}
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/**
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* Checks if the map is empty.
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*
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* @return true, if the map is empty
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*/
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public boolean isEmpty() {
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return map.isEmpty();
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}
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/**
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* Checks if the map contains the key.
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*
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* @param k the key
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*
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* @return true, if the map contains the key
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*/
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public boolean containsKey(K k) {
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return map.containsKey(k);
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}
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/**
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* Checks if the map contains the value.
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*
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* @param v the value
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*
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* @return true, if the map contains the value
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*/
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public boolean containsValue(V v) {
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return inverseMap.containsKey(v);
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}
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}

‎commons/src/test/java/com/itextpdf/commons/datastructures/BiMapTest.java

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package com.itextpdf.commons.datastructures;
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import com.itextpdf.test.annotations.type.UnitTest;
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import org.junit.Assert;
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import org.junit.Test;
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import org.junit.experimental.categories.Category;
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@Category(UnitTest.class)
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public class BiMapTest {
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@Test
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public void sizeTest01() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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Assert.assertEquals(0, map.size());
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}
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@Test
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public void sizeTest02() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertEquals(1, map.size());
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}
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@Test
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public void isEmptyTest01() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertFalse(map.isEmpty());
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}
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@Test
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public void putTest() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertEquals(1, (int) map.getByKey("a"));
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Assert.assertEquals("a", map.getByValue(1));
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}
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@Test
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public void putOnExistingKey() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.put("a", 2);
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Assert.assertEquals(2, (int) map.getByKey("a"));
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Assert.assertEquals("a", map.getByValue(2));
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}
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@Test
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public void putOnExistingValue() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.put("b", 1);
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Assert.assertEquals(1, (int) map.getByKey("b"));
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Assert.assertEquals("b", map.getByValue(1));
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}
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@Test
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public void putOnExistingKeyAndValue() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.put("a", 1);
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Assert.assertEquals(1, (int) map.getByKey("a"));
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Assert.assertEquals("a", map.getByValue(1));
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}
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@Test
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public void putMultipleValues() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.put("b", 2);
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map.put("c", 3);
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Assert.assertEquals(1, (int) map.getByKey("a"));
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Assert.assertEquals("a", map.getByValue(1));
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Assert.assertEquals(2, (int) map.getByKey("b"));
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Assert.assertEquals("b", map.getByValue(2));
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Assert.assertEquals(3, (int) map.getByKey("c"));
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Assert.assertEquals("c", map.getByValue(3));
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Assert.assertEquals(3, map.size());
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}
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@Test
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public void clearTest() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.clear();
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Assert.assertEquals(0, map.size());
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}
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@Test
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public void containsKeyTest() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertTrue(map.containsKey("a"));
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}
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@Test
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public void containsValueTest() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertTrue(map.containsValue(1));
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}
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@Test
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public void getByValue() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertEquals(1, (int) map.getByKey("a"));
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}
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@Test
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public void getByKey() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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Assert.assertEquals("a", map.getByValue(1));
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}
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@Test
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public void removeByKey() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.removeByKey("a");
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Assert.assertEquals(0, map.size());
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}
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@Test
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public void removeByValue() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.put("a", 1);
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map.removeByValue(1);
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Assert.assertEquals(0, map.size());
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}
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@Test
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public void removeOnEmptyMap() {
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BiMap<String, Integer> map = new BiMap<String, Integer>();
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map.removeByKey("a");
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map.removeByValue(1);
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Assert.assertEquals(0, map.size());
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}
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}

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