48 lines
1.6 KiB
Java
48 lines
1.6 KiB
Java
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package com.baeldung.maths;
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import java.math.BigDecimal;
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import java.math.RoundingMode;
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import java.text.DecimalFormat;
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import org.apache.commons.math3.util.Precision;
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import org.decimal4j.util.DoubleRounder;
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public class Round {
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private static final double PI = 3.1415d;
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public static void main (String args[]) {
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System.out.println("PI: " + PI);
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System.out.printf("Value with 3 digits after decimal point %.3f %n", PI);
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// OUTPUTS: Value with 3 digits after decimal point 3.142
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DecimalFormat df = new DecimalFormat("###.###");
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System.out.println(df.format(PI));
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System.out.println(round(PI, 3));
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System.out.println(roundNotPrecise(PI, 3));
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System.out.println(roundAvoid(PI, 3));
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System.out.println(Precision.round(PI, 3));
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System.out.println(DoubleRounder.round(PI, 3));
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}
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public static double round(double value, int places) {
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if (places < 0) throw new IllegalArgumentException();
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BigDecimal bd = new BigDecimal(Double.toString(value));
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bd = bd.setScale(places, RoundingMode.HALF_UP);
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return bd.doubleValue();
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}
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public static double roundNotPrecise(double value, int places) {
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if (places < 0) throw new IllegalArgumentException();
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BigDecimal bd = new BigDecimal(value);
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bd = bd.setScale(places, RoundingMode.HALF_UP);
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return bd.doubleValue();
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}
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public static double roundAvoid(double value, int places) {
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double scale = Math.pow(10, places);
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double rounded = Math.round(value * scale) / scale;
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return rounded;
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}
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}
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