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[BAEL-4617] extending enums (#10130)

This commit is contained in:
Kai Yuan 2020-11-16 19:03:15 +01:00 committed by GitHub
parent f84d19d6b0
commit 600896e842
9 changed files with 195 additions and 1 deletions
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10
core-java-modules/core-java-lang-oop-types/pom.xml
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@ -12,12 +12,20 @@
<artifactId>core-java-lang-oop-types</artifactId>
<name>core-java-lang-oop-types</name>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>${commons-lang3.version}</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>${commons-codec.version}</version>
</dependency>
</dependencies>
<properties>
<commons-codec.version>1.15</commons-codec.version>
</properties>
</project>

35
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/Application.java Normal file
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@ -0,0 +1,35 @@
package com.baeldung.enums.extendenum;
import org.apache.commons.lang3.StringUtils;
import java.util.Arrays;
import java.util.EnumMap;
import java.util.Map;
public class Application {
private static final Map<ImmutableOperation, Operator> OPERATION_MAP;
static {
OPERATION_MAP = new EnumMap<>(ImmutableOperation.class);
OPERATION_MAP.put(ImmutableOperation.TO_LOWER, String::toLowerCase);
OPERATION_MAP.put(ImmutableOperation.INVERT_CASE, StringUtils::swapCase);
OPERATION_MAP.put(ImmutableOperation.REMOVE_WHITESPACES, input -> input.replaceAll("\\s", ""));
if (Arrays.stream(ImmutableOperation.values()).anyMatch(it -> !OPERATION_MAP.containsKey(it))) {
throw new IllegalStateException("Unmapped enum constant found!");
}
}
public String applyImmutableOperation(ImmutableOperation operation, String input) {
return OPERATION_MAP.get(operation).apply(input);
}
public String getDescription(StringOperation stringOperation) {
return stringOperation.getDescription();
}
public String applyOperation(StringOperation operation, String input) {
return operation.apply(input);
}
}

26
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ApplicationWithEx.java Normal file
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@ -0,0 +1,26 @@
package com.baeldung.enums.extendenum;
import org.apache.commons.lang3.StringUtils;
import java.util.Arrays;
import java.util.EnumMap;
import java.util.Map;
public class ApplicationWithEx {
private static final Map<ImmutableOperation, Operator> OPERATION_MAP;
static {
OPERATION_MAP = new EnumMap<>(ImmutableOperation.class);
OPERATION_MAP.put(ImmutableOperation.TO_LOWER, String::toLowerCase);
OPERATION_MAP.put(ImmutableOperation.INVERT_CASE, StringUtils::swapCase);
// ImmutableOperation.REMOVE_WHITESPACES is not mapped
if (Arrays.stream(ImmutableOperation.values()).anyMatch(it -> !OPERATION_MAP.containsKey(it))) {
throw new IllegalStateException("Unmapped enum constant found!");
}
}
public String applyImmutableOperation(ImmutableOperation operation, String input) {
return OPERATION_MAP.get(operation).apply(input);
}
}

33
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/BasicStringOperation.java Normal file
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@ -0,0 +1,33 @@
package com.baeldung.enums.extendenum;
public enum BasicStringOperation implements StringOperation {
TRIM("Removing leading and trailing spaces.") {
@Override
public String apply(String input) {
return input.trim();
}
},
TO_UPPER("Changing all characters into upper case.") {
@Override
public String apply(String input) {
return input.toUpperCase();
}
},
REVERSE("Reversing the given string.") {
@Override
public String apply(String input) {
return new StringBuilder(input).reverse().toString();
}
};
private String description;
public String getDescription() {
return description;
}
BasicStringOperation(String description) {
this.description = description;
}
}

31
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ExtendedStringOperation.java Normal file
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@ -0,0 +1,31 @@
package com.baeldung.enums.extendenum;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.digest.DigestUtils;
public enum ExtendedStringOperation implements StringOperation {
MD5_ENCODE("Encoding the given string using the MD5 algorithm.") {
@Override
public String apply(String input) {
return DigestUtils.md5Hex(input);
}
},
BASE64_ENCODE("Encoding the given string using the BASE64 algorithm.") {
@Override
public String apply(String input) {
return new String(new Base64().encode(input.getBytes()));
}
};
private String description;
ExtendedStringOperation(String description) {
this.description = description;
}
@Override
public String getDescription() {
return description;
}
}

6
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ImmutableOperation.java Normal file
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@ -0,0 +1,6 @@
package com.baeldung.enums.extendenum;
public enum ImmutableOperation {
REMOVE_WHITESPACES, TO_LOWER, INVERT_CASE
}

5
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/Operator.java Normal file
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@ -0,0 +1,5 @@
package com.baeldung.enums.extendenum;
public interface Operator {
String apply(String input);
}

7
core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/StringOperation.java Normal file
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@ -0,0 +1,7 @@
package com.baeldung.enums.extendenum;
public interface StringOperation {
String getDescription();
String apply(String input);
}

43
core-java-modules/core-java-lang-oop-types/src/test/java/com/baeldung/enums/extendenum/ExtendEnumUnitTest.java Normal file
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@ -0,0 +1,43 @@
package com.baeldung.enums.extendenum;
import org.junit.Test;
import static org.junit.jupiter.api.Assertions.*;
public class ExtendEnumUnitTest {
private Application app = new Application();
@Test
public void givenAStringAndOperation_whenApplyOperation_thenGetExpectedResult() {
String input = " hello";
String expectedToUpper = " HELLO";
String expectedReverse = "olleh ";
String expectedTrim = "hello";
String expectedBase64 = "IGhlbGxv";
String expectedMd5 = "292a5af68d31c10e31ad449bd8f51263";
assertEquals(expectedTrim, app.applyOperation(BasicStringOperation.TRIM, input));
assertEquals(expectedToUpper, app.applyOperation(BasicStringOperation.TO_UPPER, input));
assertEquals(expectedReverse, app.applyOperation(BasicStringOperation.REVERSE, input));
assertEquals(expectedBase64, app.applyOperation(ExtendedStringOperation.BASE64_ENCODE, input));
assertEquals(expectedMd5, app.applyOperation(ExtendedStringOperation.MD5_ENCODE, input));
}
@Test
public void givenAStringAndImmutableOperation_whenApplyOperation_thenGetExpectedResult() {
String input = " He ll O ";
String expectedToLower = " he ll o ";
String expectedRmWhitespace = "HellO";
String expectedInvertCase = " hE LL o ";
assertEquals(expectedToLower, app.applyImmutableOperation(ImmutableOperation.TO_LOWER, input));
assertEquals(expectedRmWhitespace, app.applyImmutableOperation(ImmutableOperation.REMOVE_WHITESPACES, input));
assertEquals(expectedInvertCase, app.applyImmutableOperation(ImmutableOperation.INVERT_CASE, input));
}
@Test
public void givenUnmappedImmutableOperationValue_whenAppStarts_thenGetException() {
Throwable throwable = assertThrows(ExceptionInInitializerError.class, () -> {
ApplicationWithEx appEx = new ApplicationWithEx();
});
assertTrue(throwable.getCause() instanceof IllegalStateException);
}
}