Minify JSON in Java

JSON minification removes insignificant whitespace while preserving the represented data. A parser-based approach is safer than regular expressions because whitespace inside strings must be preserved.

Quick Start#

The following example uses the standard Java API or a widely used package for this task.

Quick start with Jackson#

1ObjectMapper mapper = new ObjectMapper();2JsonNode value = mapper.readTree(input);3String minified = mapper.writeValueAsString(value);4System.out.println(minified);

Common Operations#

This second pattern covers a common production operation or a safer way to handle real input.

Streaming large values#

1try (JsonParser parser = mapper.getFactory().createParser(inputStream);2     JsonGenerator generator = mapper.getFactory().createGenerator(outputStream)) {3    while (parser.nextToken() != null) {4        generator.copyCurrentEvent(parser);5    }6}

Important Notes#

For very large documents, a streaming parser/generator avoids holding the complete tree in memory.

Best Practices#

1. Treat external input as untrusted and handle parse/validation errors explicitly.
2. Keep encoding, units, formats, and library-specific mapping rules explicit at system boundaries.
3. Add test vectors that cover empty input, Unicode text, malformed input, and representative production data.

References#

• RFC 8259: The JSON Data Interchange Format
• Java API Documentation