diff --git a/core-java/src/main/java/com/baeldung/decimalformat/DoubletoString.java b/core-java/src/main/java/com/baeldung/decimalformat/DoubletoString.java deleted file mode 100644 index e605c5e200..0000000000 --- a/core-java/src/main/java/com/baeldung/decimalformat/DoubletoString.java +++ /dev/null @@ -1,29 +0,0 @@ -package com.baeldung.decimalformat; - -import java.math.RoundingMode; -import java.text.DecimalFormat; -import java.text.NumberFormat; - -public class DoubletoString { - - public static void main(String[] args) { - - double doubleValue = 345.56; - - System.out.println(String.valueOf((int) doubleValue)); - - System.out.println(String.format("%.0f", doubleValue)); - - NumberFormat nf = NumberFormat.getInstance(); - nf.setMaximumFractionDigits(0); - nf.setRoundingMode(RoundingMode.FLOOR); - System.out.println(nf.format(doubleValue)); - - doubleValue = Math.floor(doubleValue); - DecimalFormat df = new DecimalFormat("#,###"); - df.setRoundingMode(RoundingMode.FLOOR); - System.out.println(df.format(doubleValue)); - - } - -} diff --git a/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsManualTest.java b/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsManualTest.java new file mode 100644 index 0000000000..8dbfcaf5e7 --- /dev/null +++ b/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsManualTest.java @@ -0,0 +1,100 @@ +package com.baeldung.removingdecimals; + +import org.junit.Test; +import org.openjdk.jmh.annotations.*; +import org.openjdk.jmh.runner.Runner; +import org.openjdk.jmh.runner.options.Options; +import org.openjdk.jmh.runner.options.OptionsBuilder; + +import java.math.BigDecimal; +import java.math.RoundingMode; +import java.text.DecimalFormat; +import java.text.NumberFormat; +import java.util.concurrent.TimeUnit; + +/** + * This benchmark compares some of the approaches to formatting a floating-point + * value into a {@link String} while removing the decimal part. + * + * To run, simply run the {@link RemovingDecimalsManualTest#runBenchmarks()} test + * at the end of this class. + * + * The benchmark takes about 15 minutes to run. Since it is using {@link Mode#Throughput}, + * higher numbers mean better performance. + */ +@BenchmarkMode(Mode.Throughput) +@Warmup(iterations = 5) +@Measurement(iterations = 20) +@OutputTimeUnit(TimeUnit.MICROSECONDS) +@State(Scope.Benchmark) +public class RemovingDecimalsManualTest { + @Param(value = {"345.56", "345345345.56", "345345345345345345.56"}) double doubleValue; + + NumberFormat nf; + DecimalFormat df; + + @Setup + public void readyFormatters() { + nf = NumberFormat.getInstance(); + nf.setMaximumFractionDigits(0); + df = new DecimalFormat("#,###"); + } + + @Benchmark + public String whenCastToInt_thenValueIsTruncated() { + return String.valueOf((int) doubleValue); + } + + @Benchmark + public String whenUsingStringFormat_thenValueIsRounded() { + return String.format("%.0f", doubleValue); + } + + @Benchmark + public String whenUsingNumberFormat_thenValueIsRounded() { + nf.setRoundingMode(RoundingMode.HALF_UP); + return nf.format(doubleValue); + } + + @Benchmark + public String whenUsingNumberFormatWithFloor_thenValueIsTruncated() { + nf.setRoundingMode(RoundingMode.FLOOR); + return nf.format(doubleValue); + } + + @Benchmark + public String whenUsingDecimalFormat_thenValueIsRounded() { + df.setRoundingMode(RoundingMode.HALF_UP); + return df.format(doubleValue); + } + + @Benchmark + public String whenUsingDecimalFormatWithFloor_thenValueIsTruncated() { + df.setRoundingMode(RoundingMode.FLOOR); + return df.format(doubleValue); + } + + @Benchmark + public String whenUsingBigDecimalDoubleValue_thenValueIsTruncated() { + BigDecimal big = new BigDecimal(doubleValue); + big = big.setScale(0, RoundingMode.FLOOR); + return big.toString(); + } + + @Benchmark + public String whenUsingBigDecimalDoubleValueWithHalfUp_thenValueIsRounded() { + BigDecimal big = new BigDecimal(doubleValue); + big = big.setScale(0, RoundingMode.HALF_UP); + return big.toString(); + } + + @Test + public void runBenchmarks() throws Exception { + Options options = new OptionsBuilder() + .include(this.getClass().getSimpleName()).threads(1) + .forks(1).shouldFailOnError(true).shouldDoGC(true) + .jvmArgs("-server").build(); + + new Runner(options).run(); + } +} diff --git a/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsUnitTest.java b/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsUnitTest.java new file mode 100644 index 0000000000..2f634b553b --- /dev/null +++ b/core-java/src/test/java/com/baeldung/removingdecimals/RemovingDecimalsUnitTest.java @@ -0,0 +1,95 @@ +package com.baeldung.removingdecimals; + +import org.junit.Test; + +import java.math.BigDecimal; +import java.math.RoundingMode; +import java.text.DecimalFormat; +import java.text.NumberFormat; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertNotEquals; + +/** + * Tests that demonstrate some different approaches for formatting a + * floating-point value into a {@link String} while removing the decimal part. + */ +public class RemovingDecimalsUnitTest { + private final double doubleValue = 345.56; + + @Test + public void whenCastToInt_thenValueIsTruncated() { + String truncated = String.valueOf((int) doubleValue); + assertEquals("345", truncated); + } + + @Test + public void givenALargeDouble_whenCastToInt_thenValueIsNotTruncated() { + double outOfIntRange = 6_000_000_000.56; + String truncationAttempt = String.valueOf((int) outOfIntRange); + assertNotEquals("6000000000", truncationAttempt); + } + + @Test + public void whenUsingStringFormat_thenValueIsRounded() { + String rounded = String.format("%.0f", doubleValue); + assertEquals("346", rounded); + } + + @Test + public void givenALargeDouble_whenUsingStringFormat_thenValueIsStillRounded() { + double outOfIntRange = 6_000_000_000.56; + String rounded = String.format("%.0f", outOfIntRange); + assertEquals("6000000001", rounded); + } + + @Test + public void whenUsingNumberFormat_thenValueIsRounded() { + NumberFormat nf = NumberFormat.getInstance(); + nf.setMaximumFractionDigits(0); + nf.setRoundingMode(RoundingMode.HALF_UP); + String rounded = nf.format(doubleValue); + assertEquals("346", rounded); + } + + @Test + public void whenUsingNumberFormatWithFloor_thenValueIsTruncated() { + NumberFormat nf = NumberFormat.getInstance(); + nf.setMaximumFractionDigits(0); + nf.setRoundingMode(RoundingMode.FLOOR); + String truncated = nf.format(doubleValue); + assertEquals("345", truncated); + } + + @Test + public void whenUsingDecimalFormat_thenValueIsRounded() { + DecimalFormat df = new DecimalFormat("#,###"); + df.setRoundingMode(RoundingMode.HALF_UP); + String rounded = df.format(doubleValue); + assertEquals("346", rounded); + } + + @Test + public void whenUsingDecimalFormatWithFloor_thenValueIsTruncated() { + DecimalFormat df = new DecimalFormat("#,###"); + df.setRoundingMode(RoundingMode.FLOOR); + String truncated = df.format(doubleValue); + assertEquals("345", truncated); + } + + @Test + public void whenUsingBigDecimalDoubleValue_thenValueIsTruncated() { + BigDecimal big = new BigDecimal(doubleValue); + big = big.setScale(0, RoundingMode.FLOOR); + String truncated = big.toString(); + assertEquals("345", truncated); + } + + @Test + public void whenUsingBigDecimalDoubleValueWithHalfUp_thenValueIsRounded() { + BigDecimal big = new BigDecimal(doubleValue); + big = big.setScale(0, RoundingMode.HALF_UP); + String truncated = big.toString(); + assertEquals("346", truncated); + } +}