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BAEL-2403: Immutable Map implementations in Java

This commit is contained in:
Yatendra Goel 2018-12-02 23:45:35 +05:30
parent ce76dcde0d
commit 530395a44a
1 changed files with 87 additions and 0 deletions
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java-collections-maps/src/test/java/com/baeldung/java/map/ImmutableMapTest.java Normal file
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package com.baeldung.java.map;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.junit.jupiter.api.Test;
import com.google.common.collect.ImmutableMap;
public class ImmutableMapTest {
@Test
public void whenCollectionsUnModifiableMapMethod_thenOriginalCollectionChangesReflectInUnmodifiableMap() {
Map<String, String> mutableMap = new HashMap<>();
mutableMap.put("USA", "North America");
Map<String, String> unmodifiableMap = Collections.unmodifiableMap(mutableMap);
assertThrows(UnsupportedOperationException.class, () -> unmodifiableMap.put("Canada", "North America"));
mutableMap.remove("USA");
assertFalse(unmodifiableMap.containsKey("USA"));
mutableMap.put("Mexico", "North America");
assertTrue(unmodifiableMap.containsKey("Mexico"));
}
@Test
@SuppressWarnings("deprecation")
public void whenGuavaImmutableMapFromCopyOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() {
Map<String, String> mutableMap = new HashMap<>();
mutableMap.put("USA", "North America");
ImmutableMap<String, String> immutableMap = ImmutableMap.copyOf(mutableMap);
assertTrue(immutableMap.containsKey("USA"));
assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America"));
mutableMap.remove("USA");
assertTrue(immutableMap.containsKey("USA"));
mutableMap.put("Mexico", "North America");
assertFalse(immutableMap.containsKey("Mexico"));
}
@Test
@SuppressWarnings("deprecation")
public void whenGuavaImmutableMapFromBuilderMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() {
Map<String, String> mutableMap = new HashMap<>();
mutableMap.put("USA", "North America");
ImmutableMap<String, String> immutableMap = ImmutableMap.<String, String>builder()
.putAll(mutableMap)
.put("Costa Rica", "North America")
.build();
assertTrue(immutableMap.containsKey("USA"));
assertTrue(immutableMap.containsKey("Costa Rica"));
assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America"));
mutableMap.remove("USA");
assertTrue(immutableMap.containsKey("USA"));
mutableMap.put("Mexico", "North America");
assertFalse(immutableMap.containsKey("Mexico"));
}
@Test
@SuppressWarnings("deprecation")
public void whenGuavaImmutableMapFromOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() {
ImmutableMap<String, String> immutableMap = ImmutableMap.of("USA", "North America", "Costa Rica", "North America");
assertTrue(immutableMap.containsKey("USA"));
assertTrue(immutableMap.containsKey("Costa Rica"));
assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America"));
}
}