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-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

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

package com.fasterxml.jackson.databind.node;

import java.math.BigDecimal;
import java.math.BigInteger;

import com.fasterxml.jackson.core.JsonParser;

/**
 * Intermediate value node used for numeric nodes.
 */
public abstract class NumericNode
    extends ValueNode
{
    private static final long serialVersionUID = 1L;

    protected NumericNode() { }

    @Override
    public final JsonNodeType getNodeType()
    {
        return JsonNodeType.NUMBER;
    }

    // // // Let's re-abstract so sub-classes handle them

    @Override
    public abstract JsonParser.NumberType numberType();

    @Override public abstract Number numberValue();
    @Override public abstract int intValue();
    @Override public abstract long longValue();
    @Override public abstract double doubleValue();
    @Override public abstract BigDecimal decimalValue();
    @Override public abstract BigInteger bigIntegerValue();

    @Override public abstract boolean canConvertToInt();
    @Override public abstract boolean canConvertToLong();

    /* 
    /**********************************************************
    /* General type coercions
    /**********************************************************
     */

    @Override
    public abstract String asText();

    @Override
    public final int asInt() {
        return intValue();
    }

    @Override
    public final int asInt(int defaultValue) {
        return intValue();
    }

    @Override
    public final long asLong() {
        return longValue();
    }

    @Override
    public final long asLong(long defaultValue) {
        return longValue();
    }

    @Override
    public final double asDouble() {
        return doubleValue();
    }

    @Override
    public final double asDouble(double defaultValue) {
        return doubleValue();
    }

    /* 
    /**********************************************************
    /* Other
    /**********************************************************
     */

    /**
     * Convenience method for checking whether this node is a
     * {@link FloatNode} or {@link DoubleNode} that contains
     * "not-a-number" (NaN) value.
     *
     * @since 2.9
     */
    public boolean isNaN() {
        return false;
    }

}

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

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
Download 

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⇑⇑ Jackson - Java JSON library