How to use the Java Formatter
Format Java code in three steps:
1
Paste or upload Java code
Paste a Java class, method, or snippet into the input panel. You can also upload a .java file directly using the upload button.
2
Choose indent size and brace style
Select 2 or 4 spaces for indentation, and choose between K&R (Google/Oracle style, braces on same line) or Allman (braces on new line).
3
Format, copy, or download
Click 'Format Java' to apply formatting and syntax highlighting. Copy the result to clipboard or download as a .java file.
When to use this tool
Use the Java formatter when Java code needs consistent formatting before review or sharing:
- →Reformatting Java code copied from documentation, PDFs, or tutorials that lost brace alignment
- →Standardising indentation across multiple Java files before a team code review
- →Converting between K&R style (same-line braces) and Allman style (new-line braces) for project consistency
- →Cleaning up auto-generated Java stubs or boilerplate from IDEs that were edited manually
- →Formatting Java interview solutions quickly before sharing in a coding challenge platform
- →Tidying Spring Boot, Jakarta EE, or Android Java code snippets for blog posts and documentation
Frequently asked questions
Q:What is the difference between K&R and Allman brace style in Java?
K&R style (used by Google Java Style Guide) places the opening brace on the same line as the declaration: 'public void method() {'. Allman style places the opening brace on a new line: 'public void method()\n{'. Most Java conventions including Google and Oracle use K&R; Allman is less common in Java but preferred by some teams migrating from C#.
Q:Does the formatter handle annotations like @Override, @Service, or @Entity?
Yes — annotations are detected and kept at the correct indentation level above their associated method or class declaration. They are also highlighted in orange in the syntax-highlighted output for easy visual identification.
Q:Can I format inner classes, anonymous classes, and lambda expressions?
Yes — the formatter applies block indentation to nested class declarations, anonymous class instantiations, and lambda bodies. Each level of nesting adds one indent level, producing clean and readable output for complex nested structures.
Q:Does it work with Java generics and multi-line method signatures?
The formatter processes line-by-line and preserves multi-line method signatures and generic type declarations as-is, adjusting only the leading indentation of each line. It does not attempt to re-wrap long lines, which avoids breaking carefully formatted generic type parameters.
Q:Which Java indent size should I use — 2 or 4 spaces?
The Google Java Style Guide mandates 2-space indentation. The Oracle Code Conventions (older but still common) recommend 4 spaces. Android development (following AOSP) also uses 4 spaces. Choose the indent size that matches your project's existing style guide. If you are unsure, 4 spaces is the most widely recognised Java convention.
Q:Is the formatter suitable for Spring Boot, Jakarta EE, or Android Java code?
Yes — the formatter works with any syntactically valid Java code regardless of the framework. Spring Boot annotations (@RestController, @Autowired, @RequestMapping), Jakarta EE annotations (@Entity, @PersistenceContext), and Android-specific patterns are all handled correctly.