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

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

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/node/DecimalNode.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.databind.*;

/**
 * Numeric node that contains values that do not fit in simple
 * integer (int, long) or floating point (double) values.
 */
@SuppressWarnings("serial")
public class DecimalNode
    extends NumericNode
{
    public static final DecimalNode ZERO = new DecimalNode(BigDecimal.ZERO);

    private final static BigDecimal MIN_INTEGER = BigDecimal.valueOf(Integer.MIN_VALUE);
    private final static BigDecimal MAX_INTEGER = BigDecimal.valueOf(Integer.MAX_VALUE);
    private final static BigDecimal MIN_LONG = BigDecimal.valueOf(Long.MIN_VALUE);
    private final static BigDecimal MAX_LONG = BigDecimal.valueOf(Long.MAX_VALUE);

    final protected BigDecimal _value;

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

    public DecimalNode(BigDecimal v) { _value = v; }

    public static DecimalNode valueOf(BigDecimal d) { return new DecimalNode(d); }

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

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

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

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

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

    @Override public boolean canConvertToInt() {
        return (_value.compareTo(MIN_INTEGER) >= 0) && (_value.compareTo(MAX_INTEGER) <= 0);
    }
    @Override public boolean canConvertToLong() {
        return (_value.compareTo(MIN_LONG) >= 0) && (_value.compareTo(MAX_LONG) <= 0);
    }
    
    @Override // since 2.12
    public boolean canConvertToExactIntegral() {
        return (_value.signum() == 0)
                || (_value.scale() <= 0)
                || (_value.stripTrailingZeros().scale() <= 0);
    }

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

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

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

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


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

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

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

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

    @Override
    public final void serialize(JsonGenerator jgen, SerializerProvider provider)
        throws IOException, JsonProcessingException
    {
        // 07-Jul-2013, tatu: Should be handled by propagating setting to JsonGenerator
        //    so this should not be needed:
        /*
        if (provider.isEnabled(SerializationFeature.WRITE_BIGDECIMAL_AS_PLAIN)) {
            if (!(jgen instanceof TokenBuffer)) { // [Issue#232]
                jgen.writeNumber(((BigDecimal) _value).toPlainString());
                return;
            }
        }
        */
        jgen.writeNumber(_value);
    }

    @Override
    public boolean equals(Object o)
    {
        if (o == this) return true;
        if (o == null) return false;
        if (o instanceof DecimalNode) {
            return ((DecimalNode) o)._value.compareTo(_value) == 0;
        }
        return false;
    }

    @Override
    public int hashCode() { return Double.valueOf(doubleValue()).hashCode(); }
}

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

 

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