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BAEL-4718 using bytes array as key in HashMap (#10315)

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mdabrowski-eu 2020-12-18 06:13:31 +01:00 committed by GitHub
parent efc1277b0a
commit 83e87aebc0
2 changed files with 132 additions and 0 deletions
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28
java-collections-maps-3/src/main/java/com/baeldung/map/bytearrays/BytesKey.java Normal file
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package com.baeldung.map.bytearrays;
import java.util.Arrays;
public final class BytesKey {
private final byte[] array;
public BytesKey(byte[] array) {
this.array = array;
}
public byte[] getArray() {
return array.clone();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
BytesKey bytesKey = (BytesKey) o;
return Arrays.equals(array, bytesKey.array);
}
@Override
public int hashCode() {
return Arrays.hashCode(array);
}
}

104
java-collections-maps-3/src/test/java/com/baeldung/map/bytearrays/ByteArrayKeyUnitTest.java Normal file
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package com.baeldung.map.bytearrays;
import com.google.common.collect.ImmutableList;
import org.junit.jupiter.api.Test;
import java.util.Base64;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static org.assertj.core.api.Assertions.assertThat;
class ByteArrayKeyUnitTest {
@Test
void givenPrimitiveByteArrayKey_whenRetrievingFromMap_shouldRetrieveDifferentObjects() {
// given
byte[] key1 = {1, 2, 3};
byte[] key2 = {1, 2, 3};
String value1 = "value1";
String value2 = "value2";
Map<byte[], String> map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
// when
String retrievedValue1 = map.get(key1);
String retrievedValue2 = map.get(key2);
String retrievedValue3 = map.get(new byte[]{1, 2, 3});
// then
assertThat(retrievedValue1).isEqualTo(value1);
assertThat(retrievedValue2).isEqualTo(value2);
assertThat(retrievedValue3).isNull();
}
@Test
void givenEncodedStringKey_whenRetrievingFromMap_shouldRetrieveLastPutObject() {
// given
String key1 = Base64.getEncoder().encodeToString(new byte[]{1, 2, 3});
String key2 = Base64.getEncoder().encodeToString(new byte[]{1, 2, 3});
String value1 = "value1";
String value2 = "value2";
Map<String, String> map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
// when
String retrievedValue1 = map.get(key1);
String retrievedValue2 = map.get(key2);
// then
assertThat(key1).isEqualTo(key2);
assertThat(retrievedValue1).isEqualTo(value2);
assertThat(retrievedValue2).isEqualTo(value2);
assertThat(retrievedValue1).isEqualTo(retrievedValue2);
}
@Test
void givenByteListKey_whenRetrievingFromMap_shouldRetrieveLastPutObject() {
// given
List<Byte> key1 = ImmutableList.of((byte)1, (byte)2, (byte)3);
List<Byte> key2 = ImmutableList.of((byte)1, (byte)2, (byte)3);
String value1 = "value1";
String value2 = "value2";
Map<List<Byte>, String> map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
// when
String retrievedValue1 = map.get(key1);
String retrievedValue2 = map.get(key2);
// then
assertThat(key1).isEqualTo(key2);
assertThat(retrievedValue1).isEqualTo(value2);
assertThat(retrievedValue2).isEqualTo(value2);
assertThat(retrievedValue1).isEqualTo(retrievedValue2);
}
@Test
void givenCustomWrapperKey_whenRetrievingFromMap_shouldRetrieveLastPutObject() {
// given
BytesKey key1 = new BytesKey(new byte[]{1, 2, 3});
BytesKey key2 = new BytesKey(new byte[]{1, 2, 3});
String value1 = "value1";
String value2 = "value2";
Map<BytesKey, String> map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
// when
String retrievedValue1 = map.get(key1);
String retrievedValue2 = map.get(key2);
String retrievedValue3 = map.get(new BytesKey(new byte[]{1, 2, 3}));
// then
assertThat(key1).isEqualTo(key2);
assertThat(retrievedValue1).isEqualTo(value2);
assertThat(retrievedValue2).isEqualTo(value2);
assertThat(retrievedValue1).isEqualTo(retrievedValue2);
assertThat(retrievedValue3).isEqualTo(value2);
}
}