Java Object Selection Library

Introduction

ObjectSelector is a small, general purpose Java library for selecting objects from sets of objects. To this end, it enables users to specify simple selection predicates. The main usage scenario is to provide users of APIs or GUIs with the ability to select objects. It supports multiple features, including:

1. Converting between different data types

2. Transparent handling of sets of objects via reflection

3. Transparent handling of sets of arrays of different types

4. Creating selection predicates using the builder pattern

5. Creating selection predicates by parsing query strings

The library is extensible and suitable for building user interfaces with syntax highlighting. It has no dependencies.

Examples

Assume you want to select a set of instances of the following class:

public class Element {
	public boolean bool;
	public int integer;
	public double numeric;
}

In an API this can be done with the builder pattern:

Selector<Element> selector 
		= new SelectorBuilder<Element>(new ObjectAccessor<Element>(Element.class))
			                .begin()
			                    .field("bool").equals(true)
			                    .and()
			                    .field("integer").geq(50)
			                .end()
			                .or()
			                .field("numeric").leq(30d)
			                .build();

Moreover, the selection predicate can also be provided as a string that will be parsed by the builder:

Selector<Element> selector 
		= new SelectorBuilder<Element>(new ObjectAccessor<Element>(Element.class),
                             "('bool'='true' and 'integer'>='50') or 'numeric'<='30'")
                             .build();

The constructed selector can then be used to select objects:

for (Element element : list){
	if (selector.isSelected(element)) {
          // It's selected
    }
}

The library also features a tokenizer that can be used to graphically highlight the syntax of a predicate provided by a user and give feedback about syntax errors:

The code for this dialog can be found here.

Documentation

More examples are available in the repository.

Javadoc documentation is available here.

Downloads

Library (Version 0.1)

API documentation (Version 0.1)

Source (Version 0.1)

Developer documentation (Version 0.1)