JSON in Java [package org.json]

Click here if you just want the latest release jar file.

JSON is a light-weight, language independent, data interchange format. See http://www.JSON.org/

The files in this package implement JSON encoders/decoders in Java. It also includes the capability to convert between JSON and XML, HTTP headers, Cookies, and CDL.

This is a reference implementation. There is a large number of JSON packages in Java. Perhaps someday the Java community will standardize on one. Until then, choose carefully.

The license includes this restriction: "The software shall be used for good, not evil." If your conscience cannot live with that, then choose a different package.

The package compiles on Java 1.6-1.8.

JSONObject.java: The JSONObject can parse text from a String or a JSONTokener to produce a map-like object. The object provides methods for manipulating its contents, and for producing a JSON compliant object serialization.

JSONArray.java: The JSONArray can parse text from a String or a JSONTokener to produce a vector-like object. The object provides methods for manipulating its contents, and for producing a JSON compliant array serialization.

JSONTokener.java: The JSONTokener breaks a text into a sequence of individual tokens. It can be constructed from a String, Reader, or InputStream. It also can parse text from a String, Number, Boolean or null like "hello", 42, true, null to produce a simple json object.

JSONException.java: The JSONException is the standard exception type thrown by this package.

JSONPointer.java: Implementation of JSON Pointer (RFC 6901). Supports JSON Pointers both in the form of string representation and URI fragment representation.

JSONPropertyIgnore.java: Annotation class that can be used on Java Bean getter methods. When used on a bean method that would normally be serialized into a JSONObject, it overrides the getter-to-key-name logic and forces the property to be excluded from the resulting JSONObject.

JSONPropertyName.java: Annotation class that can be used on Java Bean getter methods. When used on a bean method that would normally be serialized into a JSONObject, it overrides the getter-to-key-name logic and uses the value of the annotation. The Bean processor will look through the class hierarchy. This means you can use the annotation on a base class or interface and the value of the annotation will be used even if the getter is overridden in a child class.

JSONString.java: The JSONString interface requires a toJSONString method, allowing an object to provide its own serialization.

JSONStringer.java: The JSONStringer provides a convenient facility for building JSON strings.

JSONWriter.java: The JSONWriter provides a convenient facility for building JSON text through a writer.

CDL.java: CDL provides support for converting between JSON and comma delimited lists.

Cookie.java: Cookie provides support for converting between JSON and cookies.

CookieList.java: CookieList provides support for converting between JSON and cookie lists.

HTTP.java: HTTP provides support for converting between JSON and HTTP headers.

HTTPTokener.java: HTTPTokener extends JSONTokener for parsing HTTP headers.

XML.java: XML provides support for converting between JSON and XML.

JSONML.java: JSONML provides support for converting between JSONML and XML.

XMLTokener.java: XMLTokener extends JSONTokener for parsing XML text.

Unit tests are maintained in a separate project. Contributing developers can test JSON-java pull requests with the code in this project: https://github.com/stleary/JSON-Java-unit-test

Numeric types in this package comply with ECMA-404: The JSON Data Interchange Format and RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format. This package fully supports Integer, Long, and Double Java types. Partial support for BigInteger and BigDecimal values in JSONObject and JSONArray objects is provided in the form of get(), opt(), and put() API methods.

Although 1.6 compatibility is currently supported, it is not a project goal and may be removed in some future release.

In compliance with RFC8259 page 10 section 9, the parser is more lax with what is valid JSON than the Generator. For Example, the tab character (U+0009) is allowed when reading JSON Text strings, but when output by the Generator, tab is properly converted to \t in the string. Other instances may occur where reading invalid JSON text does not cause an error to be generated. Malformed JSON Texts such as missing end " (quote) on strings or invalid number formats (1.2e6.3) will cause errors as such documents can not be read reliably.

Some notible exceptions that the JSON Parser in this library accepts are:

• Unquoted keys { key: "value" }
• Unquoted values { "key": value }
• Unescaped literals like "tab" in string values { "key": "value with an unescaped tab" }
• Numbers out of range for Double or Long are parsed as strings

Release history:

20190722    Recent commits

20180813    POM change to include Automatic-Module-Name (#431)

20180130    Recent commits

20171018    Checkpoint for recent commits.

20170516    Roll up recent commits.

20160810    Revert code that was breaking opt*() methods.

20160807    This release contains a bug in the JSONObject.opt*() and JSONArray.opt*() methods,
it is not recommended for use.
Java 1.6 compatability fixed, JSONArray.toList() and JSONObject.toMap(),
RFC4180 compatibility, JSONPointer, some exception fixes, optional XML type conversion.
Contains the latest code as of 7 Aug, 2016

20160212    Java 1.6 compatibility, OSGi bundle. Contains the latest code as of 12 Feb, 2016.

20151123    JSONObject and JSONArray initialization with generics. Contains the
latest code as of 23 Nov, 2015.

20150729    Checkpoint for Maven central repository release. Contains the latest code
as of 29 July, 2015.

JSON-java releases can be found by searching the Maven repository for groupId "org.json" and artifactId "json". For example: https://search.maven.org/search?q=g:org.json%20AND%20a:json&core=gav

Unit tests

The test suite can be run by calling

mvn test

Conventions

Test filenames should consist of the name of the module being tested, with the suffix "Test". For example, Cookie.java is tested by CookieTest.java.

The fundamental issues with JSON-Java testing are:

• JSONObjects are unordered, making simple string comparison ineffective.
• Comparisons via equals() is not currently supported. Neither JSONArray nor JSONObject override hashCode() or equals(), so comparison defaults to the Object equals(), which is not useful.
• Access to the JSONArray and JSONObject internal containers for comparison is not currently available.

General issues with unit testing are:

• Just writing tests to make coverage goals tends to result in poor tests.
• Unit tests are a form of documentation - how a given method actually works is demonstrated by the test. So for a code reviewer or future developer looking at code a good test helps explain how a function is supposed to work according to the original author. This can be difficult if you are not the original developer.
• It is difficult to evaluate unit tests in a vacuum. You also need to see the code being tested to understand if a test is good.
• Without unit tests it is hard to feel confident about the quality of the code, especially when fixing bugs or refactoring. Good tests prevents regressions and keeps the intent of the code correct.
• If you have unit test results along with pull requests, the reviewer has an easier time understanding your code and determining if the it works as intended.

When you start working on a test, add the empty file to the repository and update the readme, so that others will know that test is taken.

Caveats: JSON-Java is Java 1.6-compatible, but JSON-Java-unit-tests requires Java 1.8. If you see this error when building JSON-Java-unit-test, make sure you have 1.8 installed, on your path, and set in JAVA_HOME:

Execution failed for task ':compileJava'.
> invalid flag: -parameters

Resource files used in test
EnumTest.java
MyBean.java
MyBigNumberBean.java
MyEnum.java
MyEnumClass.java
MyEnumField.java
MyJsonString.java
MyPublicClass.java
PropertyTest.java
JunitTestSuite.java
StringsResourceBundle.java
TestRunner.java
Util.java

How to release

• Adapt the version number in the pom file
• Run

mvn clean deploy

You will need permissions for the org.json library given by the sonatype maven central team.