Rounds a double value to the exact value to one decimal point. - Java java.lang

Java examples for java.lang:float

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Description

Rounds a double value to the exact value to one decimal point.

Demo Code


import java.math.RoundingMode;
import java.text.DecimalFormat;

public class Main{
    /**//from   ww  w .  ja  va2 s .c om
     * Rounds a double value to the exact value to one decimal point.
     *
     * <pre>
     *   NumberUtils.roundExact(1.234D)               = 1.2D
     * </pre>
     *
     * @param value double value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(double value) {
        return roundExact("#.#", value);
    }
    /**
     * Rounds a float value to the exact value to one decimal point.
     *
     * <pre>
     *   NumberUtils.roundExact(1.234F)               = 1.2F
     * </pre>
     *
     * @param value float value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(float value) {
        return roundExact("#.#", value);
    }
    /**
     * Rounds a double value to the exact value with the given format.
     *
     * <pre>
     *   NumberUtils.roundExact(-1, 1.234D)               = 1.D
     *   NumberUtils.roundExact(0, 1.234D)                = 1.D
     *   NumberUtils.roundExact(1, 1.234D)                = 1.2D
     *   NumberUtils.roundExact(2, 1.234D)                = 1.23D
     *   NumberUtils.roundExact(3, 1.234D)                = 1.234D
     * </pre>
     *
     * @param decimalPlaces decimal places to round to
     * @param value double value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(int decimalPlaces, double value) {
        return roundExact(
                "#."
                        + org.apache.commons.lang.StringUtils.repeat("#",
                                decimalPlaces), value);
    }
    /**
     * Rounds a float value to the exact value with the given format.
     *
     * <pre>
     *   NumberUtils.roundExact(-1, 1.234F)               = 1.F
     *   NumberUtils.roundExact(0, 1.234F)                = 1.F
     *   NumberUtils.roundExact(1, 1.234F)                = 1.2F
     *   NumberUtils.roundExact(2, 1.234F)                = 1.23F
     *   NumberUtils.roundExact(3, 1.234F)                = 1.234F
     * </pre>
     *
     * @param decimalPlaces decimal places to round to
     * @param value float value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(int decimalPlaces, float value) {
        return roundExact(
                "#."
                        + org.apache.commons.lang.StringUtils.repeat("#",
                                decimalPlaces), value);
    }
    /**
     * Rounds a double value to the exact value with the given format.
     *
     * <pre>
     *   NumberUtils.roundExact("#.", 1.234D)               = 1.D
     *   NumberUtils.roundExact("#.#", 1.234D)              = 1.2D
     *   NumberUtils.roundExact("#.##", 1.234D)             = 1.23D
     *   NumberUtils.roundExact("#.###", 1.234D)            = 1.234D
     * </pre>
     *
     * @param format format to display {@code value} in, see {@link DecimalFormat}
     * @param value double value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(String format, double value) {
        DecimalFormat df = new DecimalFormat(format);
        df.setRoundingMode(RoundingMode.DOWN);
        return df.format(value);
    }
    /**
     * Rounds a float value to the exact value with the given format.
     *
     * <pre>
     *   NumberUtils.roundExact("#.", 1.234F)               = 1.F
     *   NumberUtils.roundExact("#.#", 1.234F)              = 1.2F
     *   NumberUtils.roundExact("#.##", 1.234F)             = 1.23F
     *   NumberUtils.roundExact("#.###", 1.234F)            = 1.234F
     * </pre>
     *
     * @param format format to display {@code value} in, see {@link DecimalFormat}
     * @param value float value to round
     *
     * @return rounded {@code value} based on the {@code format}
     */
    public static String roundExact(String format, float value) {
        DecimalFormat df = new DecimalFormat(format);
        df.setRoundingMode(RoundingMode.DOWN);
        return df.format(value);
    }
}

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