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

Jackson Annotations Source Code files are provided in the source packge (jackson-annotations-2.12.4-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Annotations Source Code below:

⏎ com/fasterxml/jackson/databind/node/DoubleNode.java

package com.fasterxml.jackson.databind.node;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.io.NumberOutput;
import com.fasterxml.jackson.databind.SerializerProvider;


/**
 * Numeric node that contains 64-bit ("double precision")
 * floating point values simple 32-bit integer values.
 */
@SuppressWarnings("serial")
public class DoubleNode
    extends NumericNode
{
    protected final double _value;

    /* 
    /**********************************************************
    /* Construction
    /**********************************************************
     */

    public DoubleNode(double v) { _value = v; }

    public static DoubleNode valueOf(double v) { return new DoubleNode(v); }

    /* 
    /**********************************************************
    /* BaseJsonNode extended API
    /**********************************************************
     */

    @Override public JsonToken asToken() { return JsonToken.VALUE_NUMBER_FLOAT; }

    @Override
    public JsonParser.NumberType numberType() { return JsonParser.NumberType.DOUBLE; }

    /* 
    /**********************************************************
    /* Overrridden JsonNode methods
    /**********************************************************
     */

    @Override
    public boolean isFloatingPointNumber() { return true; }

    @Override
    public boolean isDouble() { return true; }

    @Override public boolean canConvertToInt() {
        return (_value >= Integer.MIN_VALUE && _value <= Integer.MAX_VALUE);
    }
    @Override public boolean canConvertToLong() {
        return (_value >= Long.MIN_VALUE && _value <= Long.MAX_VALUE);
    }

    @Override // since 2.12
    public boolean canConvertToExactIntegral() {
        return !Double.isNaN(_value) && !Double.isInfinite(_value)
                && (_value == Math.rint(_value));
    }

    @Override
    public Number numberValue() {
        return Double.valueOf(_value);
    }

    @Override
    public short shortValue() { return (short) _value; }

    @Override
    public int intValue() { return (int) _value; }

    @Override
    public long longValue() { return (long) _value; }

    @Override
    public float floatValue() { return (float) _value; }

    @Override
    public double doubleValue() { return _value; }

    @Override
    public BigDecimal decimalValue() { return BigDecimal.valueOf(_value); }

    @Override
    public BigInteger bigIntegerValue() {
        return decimalValue().toBigInteger();
    }

    @Override
    public String asText() {
        return NumberOutput.toString(_value);
    }

    // @since 2.9
    @Override
    public boolean isNaN() {
        return Double.isNaN(_value) || Double.isInfinite(_value);
    }

    @Override
    public final void serialize(JsonGenerator g, SerializerProvider provider) throws IOException {
        g.writeNumber(_value);
    }

    @Override
    public boolean equals(Object o)
    {
        if (o == this) return true;
        if (o == null) return false;
        if (o instanceof DoubleNode) {
            // We must account for NaNs: NaN does not equal NaN, therefore we have
            // to use Double.compare().
            final double otherValue = ((DoubleNode) o)._value;
            return Double.compare(_value, otherValue) == 0;
        }
        return false;
    }

    @Override
    public int hashCode()
    {
        // same as hashCode Double.class uses
        long l = Double.doubleToLongBits(_value);
        return ((int) l) ^ (int) (l >> 32);

    }
}

⏎ com/fasterxml/jackson/databind/node/DoubleNode.java

 

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