Java Decimal Format toString(final Double value)

Description

to String

License

Apache License

Declaration

private static String toString(final Double value) 

Method Source Code

//package com.java2s;
/*//from w  w  w .  ja  v a 2  s .c om
 * Copyright (c) 2012-2014 Spotify AB
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.text.NumberFormat;
import java.util.Locale;

public class Main {
    private static ThreadLocal<NumberFormat> formatters = new ThreadLocal<NumberFormat>() {

        @Override
        protected NumberFormat initialValue() {
            NumberFormat nf = NumberFormat.getNumberInstance(Locale.US);
            nf.setMaximumFractionDigits(9); // 9 is randomly picked
            nf.setGroupingUsed(false);
            return nf;
        }
    };

    private static String toString(final Double value) {
        if (Double.isNaN(value) || Double.isInfinite(value)) {
            // http://munin-monitoring.org/wiki/network-protocol
            // "Numeric value, or 'U'"
            return "U";
        } else {
            return formatters.get().format(value);
        }
    }

    private static String toString(final Float value) {
        if (Float.isNaN(value) || Float.isInfinite(value)) {
            // http://munin-monitoring.org/wiki/network-protocol
            // "Numeric value, or 'U'"
            return "U";
        } else {
            return formatters.get().format(value);
        }
    }

    /**
     * Used for gauges where the type of the value is not known
     * @param value The value, can be of any type or null, but {@link Number} will be properly
     *              formatted
     * @return The formatted value, toString() used for non-Number values, null for null input
     *         values
     */
    public static String toString(final Object value) {
        if (value instanceof Double) {
            return toString((Double) value);
        } else if (value instanceof Float) {
            return toString((Float) value);
        } else if (value instanceof Number) {
            return formatters.get().format(value);
        } else if (value != null) {
            // fallback if something not a number is used
            return value.toString();
        } else {
            return null;
        }
    }
}

Related

1. toString(double value)
2. toString(double value, int precision)
3. toString(double[] array)
4. toString(Double[] input)
5. toString(double[][] a, int decimals)
6. toString(final double value, final int maxDecimalPlaces)
7. toStringForHumans(double doubleToConvert)
8. toStringNoDigits(double[] v)
9. toStringScientific(double x)