java-util

Rare, hard-to-find utilities that are thoroughly tested (> 98% code coverage via JUnit tests). Available on Maven Central. This library has no dependencies on other libraries for runtime. The.jarfile is 232K. Works withJDK 1.8throughJDK 21. The classes in the.jarfile are version 52 (JDK 1.8).

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To include in your project:

GradleF

implementation 'com.cedarsoftware:java-util:2.4.2'

Maven

<dependency>
  <groupId>com.cedarsoftware</groupId>
  <artifactId>java-util</artifactId>
  <version>2.4.2</version>
</dependency>

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Since Java 1.5, you can statically import classes. Using this technique with many of the classes below, it makes their methods directly accessible in your source code, keeping your source code smaller and easier to read. For example:

import static com.cedarsoftware.util.Converter.*;

will permit you to write:

...
Calendar cal = convertToCalendar("2019/11/17");
Date date = convertToDate("November 17th, 2019 4:45pm");
TimeStamp stamp = convertToTimeStamp(cal);
AtomicLong atomicLong = convertToAtomicLong("123128300")
String s = convertToString(atomicLong)
...

Included in java-util:

• ArrayUtilities - Useful utilities for working with Java's arrays []
• ByteUtilities - Useful routines for converting byte[] to HEX character [] and visa-versa.
• ClassUtilities - Useful utilities for Class work. For example, call computeInheritanceDistance(source, destination) to get the inheritance distance (number of super class steps to make it from source to destination. It will return the distance as an integer. If there is no inheritance relationship between the two, then -1 is returned. The primitives and primitive wrappers return 0 distance as if they are the same class.
• Sets
  • CompactSet - Small memory footprint Set that expands to a HashSet when size() > compactSize().
  • CompactLinkedSet - Small memory footprint Set that expands to a LinkedHashSet when size() > compactSize().
  • CompactCILinkedSet - Small memory footprint Set that expands to a case-insensitive LinkedHashSet when size() > compactSize().
  • CompactCIHashSet - Small memory footprint Set that expands to a case-insensitive HashSet when size() > compactSize().
  • CaseInsensitiveSet - Set that ignores case for Strings contained within.
• Maps
  • CompactMap - Small memory footprint Map that expands to a HashMap when size() > compactSize() entries.
  • CompactLinkedMap - Small memory footprint Map that expands to a LinkedHashMap when size() > compactSize() entries.
  • CompactCILinkedMap - Small memory footprint Map that expands to a case-insensitive LinkedHashMap when size() > compactSize() entries.
  • CompactCIHashMap - Small memory footprint Map that expands to a case-insensitive HashMap when size() > compactSize() entries.
  • CaseInsensitiveMap - Map that ignores case when Strings are used as keys.
  • LRUCache - Thread safe LRUCache that implements the full Map API and supports a maximum capacity. Once max capacity is reached, placing another item in the cache will cause the eviction of the item that was the least recently used (LRU).
  • TrackingMap - Map class that tracks when the keys are accessed via .get() or .containsKey(). Provided by @seankellner
• Converter - Convert from one instance to another. For example, convert("45.3", BigDecimal.class) will convert the String to a BigDecimal. Works for all primitives, primitive wrappers, Date, java.sql.Date, String, BigDecimal, BigInteger, AtomicBoolean, AtomicLong, etc. The method is very generous on what it allows to be converted. For example, a Calendar instance can be input for a Date or Long. Examine source to see all possibilities.
• DateUtilities - Robust date String parser that handles date/time, date, time, time/date, string name months or numeric months, skips comma, etc. English month names only (plus common month name abbreviations), time with/without seconds or milliseconds, y/m/d and m/d/y ordering as well.
• DeepEquals - Compare two object graphs and return 'true' if they are equivalent, 'false' otherwise. This will handle cycles in the graph, and will call an equals() method on an object if it has one, otherwise it will do a field-by-field equivalency check for non-transient fields. Has options to turn on/off using .equals() methods that may exist on classes.
• IO
  • FastReader - Works like BufferedReader and PushbackReader without the synchronization. Tracks line and col by watching for 0x0a, which can be useful when reading text/json/xml files. You can .pushback() a character read, which is very useful in parsers.
  • FastWriter - Works like BufferedWriter without the synchronization.
  • FastByteArrayInputStream - Unlike the JDK ByteArrayInputStream, FastByteArrayInputStream is not synchronized.
  • FastByteArrayOutputStream - Unlike the JDK ByteArrayOutputStream, FastByteArrayOutputStream is not synchronized.
  • IOUtilities - Handy methods for simplifying I/O including such niceties as properly setting up the input stream for HttpUrlConnections based on their specified encoding. Single line .close() method that handles exceptions for you.
• EncryptionUtilities - Makes it easy to compute MD5, SHA-1, SHA-256, SHA-512 checksums for Strings, byte[], as well as making it easy to AES-128 encrypt Strings and byte[]'s.
• Executor - One line call to execute operating system commands. Executor executor = new Executor(); executor.exec('ls -l'); Call executor.getOut() to fetch the output, executor.getError() retrieve error output. If a -1 is returned, there was an error.
• GraphComparator - Compare any two Java object graphs. It generates a List of Delta objects which describe the difference between the two Object graphs. This Delta list can be played back, such that List deltas = GraphComparator.delta(source, target); GraphComparator.applyDelta(source, deltas) will bring source up to match target. See JUnit test cases for example usage. This is a completely thorough graph difference (and apply delta), including support for Array, Collection, Map, and object field differences.
• MathUtilities - Handy mathematical algorithms to make your code smaller. For example, minimum of array of values.
• ReflectionUtils - Simple one-liners for many common reflection tasks. Speedy reflection calls due to Method caching.
• StringUtilities - Helpful methods that make simple work of common String related tasks.
• SystemUtilities - A Helpful utility methods for working with external entities like the OS, environment variables, and system properties.
• Traverser - Pass any Java object to this Utility class, it will call your passed in anonymous method for each object it encounters while traversing the complete graph. It handles cycles within the graph. Permits you to perform generalized actions on all objects within an object graph.
• UniqueIdGenerator - Generates unique Java long value, that can be deterministically unique across up to 100 servers in a cluster (if configured with an environment variable), the ids are monotonically increasing, and can generate the ids at a rate of about 10 million per second. Because the current time to the millisecond is embedded in the id, one can back-calculate when the id was generated.

See changelog.md for revision history.

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By: John DeRegnaucourt and Kenny Partlow