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BAEL-7448: BigDecimal to Integer (#15569)

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Eugene Kovko 2024-01-08 04:07:28 +01:00 committed by GitHub
parent b41a78fb39
commit 0e38c09d04
2 changed files with 152 additions and 0 deletions
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119
core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/bigdecimaltointeger/BigDecimalToIntegerConversionUnitTest.java Normal file
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package com.baeldung.bigdecimaltointeger;
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
import java.math.BigDecimal;
import java.math.RoundingMode;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ArgumentsSource;
import org.junit.jupiter.params.provider.ValueSource;
class BigDecimalToIntegerConversionUnitTest {
@ParameterizedTest
@ArgumentsSource(SmallBigDecimalConversionArgumentsProvider.class)
void givenSmallBigDecimalWhenConvertToIntegerThenWontLosePrecision(BigDecimal given, int expected) {
int actual = given.intValue();
assertThat(actual).isEqualTo(expected);
}
@ParameterizedTest
@ValueSource(longs = {Long.MAX_VALUE, Long.MAX_VALUE - 1, Long.MAX_VALUE - 2,
Long.MAX_VALUE - 3, Long.MAX_VALUE - 4, Long.MAX_VALUE - 5,
Long.MAX_VALUE - 6, Long.MAX_VALUE - 7, Long.MAX_VALUE - 8})
void givenLargeBigDecimalWhenConvertToIntegerThenLosePrecision(long expected) {
BigDecimal decimal = BigDecimal.valueOf(expected);
int actual = decimal.intValue();
assertThat(actual)
.isNotEqualTo((int) expected)
.isEqualTo((int) expected - Long.MAX_VALUE - 1);
}
@ParameterizedTest
@ValueSource(doubles = {0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5})
void givenLargeBigDecimalWhenConvertToIntegerThenLosePrecision(double given) {
BigDecimal decimal = BigDecimal.valueOf(given);
int integerValue = decimal.intValue();
double actual = Integer.valueOf(integerValue).doubleValue();
assertThat(actual)
.isEqualTo((int) given)
.isNotEqualTo(given);
}
@ParameterizedTest
@ValueSource(doubles = {0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5, 8.5})
void givenLargeBigDecimalWhenConvertToIntegerWithRoundingUpThenLosePrecision(double given) {
BigDecimal decimal = BigDecimal.valueOf(given);
int integerValue = decimal.setScale(0, RoundingMode.CEILING).intValue();
double actual = Integer.valueOf(integerValue).doubleValue();
assertThat(actual)
.isEqualTo(Math.ceil(given))
.isNotEqualTo(given);
}
@ParameterizedTest
@ValueSource(doubles = {
0.0, 1.00, 2.000, 3.0000,
4.00000, 5.000000, 6.00000000,
7.000000000, 8.0000000000})
void givenLargeBigDecimalWhenCheckScaleThenItGreaterThanZero(double given) {
BigDecimal decimal = BigDecimal.valueOf(given);
assertThat(decimal.scale()).isPositive();
assertThat(decimal.toBigInteger()).isEqualTo((int) given);
}
@ParameterizedTest
@ValueSource(doubles = {Long.MAX_VALUE - 0.5, Long.MAX_VALUE - 1.5, Long.MAX_VALUE - 2.5,
Long.MAX_VALUE - 3.5, Long.MAX_VALUE - 4.5, Long.MAX_VALUE - 5.5,
Long.MAX_VALUE - 6.5, Long.MAX_VALUE - 7.5, Long.MAX_VALUE - 8.5})
void givenLargeBigDecimalWhenConvertToIntegerThenLosePrecisionFromBothSides(double given) {
BigDecimal decimal = BigDecimal.valueOf(given);
int integerValue = decimal.intValue();
double actual = Integer.valueOf(integerValue).doubleValue();
assertThat(actual)
.isNotEqualTo(Math.floor(given))
.isNotEqualTo(given);
}
@ParameterizedTest
@ValueSource(longs = {Long.MAX_VALUE, Long.MAX_VALUE - 1, Long.MAX_VALUE - 2,
Long.MAX_VALUE - 3, Long.MAX_VALUE - 4, Long.MAX_VALUE - 5,
Long.MAX_VALUE - 6, Long.MAX_VALUE - 7, Long.MAX_VALUE - 8})
void givenLargeBigDecimalWhenConvertToExactIntegerThenThrowException(long expected) {
BigDecimal decimal = BigDecimal.valueOf(expected);
assertThatExceptionOfType(ArithmeticException.class)
.isThrownBy(decimal::intValueExact);
}
@ParameterizedTest
@ValueSource(longs = {
Long.MAX_VALUE, Long.MAX_VALUE - 1, Long.MAX_VALUE - 2,
Long.MIN_VALUE, Long.MIN_VALUE + 1, Long.MIN_VALUE + 2,
0, 1, 2
})
void givenLargeBigDecimalWhenConvertToIntegerThenSetTheMaxOrMinValue(long expected) {
BigDecimal decimal = BigDecimal.valueOf(expected);
boolean tooBig = isTooBig(decimal);
boolean tooSmall = isTooSmall(decimal);
int actual;
if (tooBig) {
actual = Integer.MAX_VALUE;
} else if (tooSmall) {
actual = Integer.MIN_VALUE;
} else {
actual = decimal.intValue();
}
assertThat(tooBig).isEqualTo(actual == Integer.MAX_VALUE);
assertThat(tooSmall).isEqualTo(actual == Integer.MIN_VALUE);
assertThat(!tooBig && !tooSmall).isEqualTo(actual == expected);
}
private static boolean isTooSmall(BigDecimal decimal) {
return BigDecimal.valueOf(Integer.MIN_VALUE).compareTo(decimal) > 0;
}
private static boolean isTooBig(BigDecimal decimal) {
return BigDecimal.valueOf(Integer.MAX_VALUE).compareTo(decimal) < 0;
}
}

33
core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/bigdecimaltointeger/SmallBigDecimalConversionArgumentsProvider.java Normal file
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package com.baeldung.bigdecimaltointeger;
import java.math.BigDecimal;
import java.util.stream.Stream;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.ArgumentsProvider;
public class SmallBigDecimalConversionArgumentsProvider implements ArgumentsProvider {
@Override
public Stream<? extends Arguments> provideArguments(ExtensionContext context) {
return Stream.of(
Arguments.of(BigDecimal.valueOf(0), 0),
Arguments.of(BigDecimal.valueOf(1), 1),
Arguments.of(BigDecimal.valueOf(2), 2),
Arguments.of(BigDecimal.valueOf(3), 3),
Arguments.of(BigDecimal.valueOf(4), 4),
Arguments.of(BigDecimal.valueOf(5), 5),
Arguments.of(BigDecimal.valueOf(6), 6),
Arguments.of(BigDecimal.valueOf(7), 7),
Arguments.of(BigDecimal.valueOf(8), 8),
Arguments.of(BigDecimal.valueOf(9), 9),
Arguments.of(BigDecimal.valueOf(10), 10),
Arguments.of(BigDecimal.valueOf(11), 11),
Arguments.of(BigDecimal.valueOf(12), 12),
Arguments.of(BigDecimal.valueOf(13), 13),
Arguments.of(BigDecimal.valueOf(14), 14),
Arguments.of(BigDecimal.valueOf(15), 15)
);
}
}