Created
September 21, 2016 23:08
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Misc. utilities for java
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public class TestToggleEnum { | |
enum TestEnum { | |
A, | |
B, | |
C | |
} | |
@Test | |
public void incrementEnum() { | |
TestEnum test = TestEnum.A; | |
test = Utils.toggleEnum(true, test); | |
assertEquals(test, TestEnum.B); | |
} | |
@Test | |
public void decrementEnum() { | |
TestEnum test = TestEnum.C; | |
test = Utils.toggleEnum(false, test); | |
assertEquals(test, TestEnum.B); | |
} | |
@Test | |
public void incrementEnumOverflow() { | |
TestEnum test = TestEnum.C; | |
test = Utils.toggleEnum(true, test); | |
assertEquals(test, TestEnum.A); | |
} | |
@Test | |
public void decrementEnumOverflow() { | |
TestEnum test = TestEnum.A; | |
test = Utils.toggleEnum(false, test); | |
assertEquals(test, TestEnum.C); | |
} | |
} |
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public class Utils { | |
/** | |
* Toggle the enum either forward or reverse | |
* @param forward If the enum should go down the enum (true) or up the enum (false) | |
* @param enums The enum value | |
* @return The new, same-type enum | |
* | |
* @author joeychor | |
*/ | |
@SuppressWarnings("unchecked") | |
public static <T extends Enum<?>> T toggleEnum(boolean forward, Enum<? extends T> enums) { | |
int offset = forward ? 1 : -1; | |
int index = enums.ordinal(); | |
int length = enums.getClass().getEnumConstants().length; | |
if ((index + offset) >= length) { | |
return (T) enums.getClass().getEnumConstants()[0]; | |
} else if ((index + offset) < 0) { | |
return (T) enums.getClass().getEnumConstants()[length - 1]; | |
} else { | |
return (T) enums.getClass().getEnumConstants()[index + offset]; | |
} | |
} | |
} |
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