Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Core Source Code files are provided in the source packge (jackson-core-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Core Source Code below:

⏎ com/fasterxml/jackson/core/io/doubleparser/FastDoubleParser.java

/**
 * References:
 * <dl>
 *     <dt>This class has been derived from "FastDoubleParser".</dt>
 *     <dd>Copyright (c) Werner Randelshofer. Apache 2.0 License.
 *         <a href="https://github.com/wrandelshofer/FastDoubleParser">github.com</a>.</dd>
 * </dl>
 */

package com.fasterxml.jackson.core.io.doubleparser;

/**
 * Provides static method for parsing a {@code double} from a
 * {@link CharSequence}, {@code char} array or {@code byte} array.
 */
public class FastDoubleParser {


    /**
     * Don't let anyone instantiate this class.
     */
    private FastDoubleParser() {

    }

    /**
     * Convenience method for calling {@link #parseDouble(CharSequence, int, int)}.
     *
     * @param str the string to be parsed
     * @return the parsed double value
     * @throws NumberFormatException if the string can not be parsed
     */
    public static double parseDouble(CharSequence str) throws NumberFormatException {
        return parseDouble(str, 0, str.length());
    }

    /**
     * Parses a {@code FloatingPointLiteral} from a {@link CharSequence} and converts it
     * into a {@code double} value.
     * <p>
     * See {@link com.fasterxml.jackson.core.io.doubleparser} for the syntax of {@code FloatingPointLiteral}.
     *
     * @param str    the string to be parsed
     * @param offset the start offset of the {@code FloatingPointLiteral} in {@code str}
     * @param length the length of {@code FloatingPointLiteral} in {@code str}
     * @return the parsed double value
     * @throws NumberFormatException if the string can not be parsed
     */
    public static double parseDouble(CharSequence str, int offset, int length) throws NumberFormatException {
        long bitPattern = new DoubleBitsFromCharSequence().parseFloatingPointLiteral(str, offset, length);
        if (bitPattern == AbstractFloatValueParser.PARSE_ERROR) {
            throw new NumberFormatException("Illegal input");
        }
        return Double.longBitsToDouble(bitPattern);
    }

    /**
     * Convenience method for calling {@link #parseDouble(char[], int, int)}.
     *
     * @param str the string to be parsed
     * @return the parsed double value
     * @throws NumberFormatException if the string can not be parsed
     */
    public static double parseDouble(char[] str) throws NumberFormatException {
        return parseDouble(str, 0, str.length);
    }

    /**
     * Parses a {@code FloatingPointLiteral} from a {@code byte}-Array and converts it
     * into a {@code double} value.
     * <p>
     * See {@link com.fasterxml.jackson.core.io.doubleparser} for the syntax of {@code FloatingPointLiteral}.
     *
     * @param str    the string to be parsed, a byte array with characters
     *               in ISO-8859-1, ASCII or UTF-8 encoding
     * @param offset The index of the first character to parse
     * @param length The number of characters to parse
     * @return the parsed double value
     * @throws NumberFormatException if the string can not be parsed
     */
    public static double parseDouble(char[] str, int offset, int length) throws NumberFormatException {
        long bitPattern = new DoubleBitsFromCharArray().parseFloatingPointLiteral(str, offset, length);
        if (bitPattern == AbstractFloatValueParser.PARSE_ERROR) {
            throw new NumberFormatException("Illegal input");
        }
        return Double.longBitsToDouble(bitPattern);
    }

    /**
     * Parses a {@code FloatingPointLiteral} from a {@link CharSequence} and converts it
     * into a bit pattern that encodes a {@code double} value.
     * <p>
     * See {@link com.fasterxml.jackson.core.io.doubleparser} for the syntax of {@code FloatingPointLiteral}.
     * <p>
     * Usage example:
     * <pre>
     *     long bitPattern = parseDoubleBits("3.14", 0, 4);
     *     if (bitPattern == -1L) {
     *         ...handle parse error...
     *     } else {
     *         double d = Double.longBitsToDouble(bitPattern);
     *     }
     * </pre>
     *
     * @param str    the string to be parsed
     * @param offset the start offset of the {@code FloatingPointLiteral} in {@code str}
     * @param length the length of {@code FloatingPointLiteral} in {@code str}
     * @return the bit pattern of the parsed value, if the input is legal;
     * otherwise, {@code -1L}.
     */
    public static long parseDoubleBits(CharSequence str, int offset, int length) {
        return new DoubleBitsFromCharSequence().parseFloatingPointLiteral(str, offset, length);
    }

    /**
     * Parses a {@code FloatingPointLiteral} from a {@code byte}-Array and converts it
     * into a bit pattern that encodes a {@code double} value.
     * <p>
     * See {@link com.fasterxml.jackson.core.io.doubleparser} for the syntax of {@code FloatingPointLiteral}.
     * <p>
     * See {@link #parseDoubleBits(CharSequence, int, int)} for a usage example.
     *
     * @param str    the string to be parsed, a byte array with characters
     *               in ISO-8859-1, ASCII or UTF-8 encoding
     * @param offset The index of the first character to parse
     * @param length The number of characters to parse
     * @return the bit pattern of the parsed value, if the input is legal;
     * otherwise, {@code -1L}.
     */
    public static long parseDoubleBits(char[] str, int offset, int length) {
        return new DoubleBitsFromCharArray().parseFloatingPointLiteral(str, offset, length);
    }
}

⏎ com/fasterxml/jackson/core/io/doubleparser/FastDoubleParser.java

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File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05
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