Java Method Generator
Describe a method and get a complete Java method inside a class: access and other modifiers, final parameters with proper types, a return type that can be wrapped in Optional, a throws clause with the needed imports, Javadoc with every tag, Objects.requireNonNull for reference parameters, range checks for sizes and a placeholder body that compiles.
- Runs in your browser
- No sign-up
- Free to use
How to use Java Method Generator
- Enter the method name and the class it belongs to.
- List the parameters as name: type.
- Set the return type, access and modifiers.
- Copy the method and implement the TODO.
Java Method Generator features
Modifiers
public, protected, private, package-private, static, final, synchronized.
Javadoc
@param, @return and @throws, including null and range checks.
Null safety
Objects.requireNonNull for required reference parameters.
Optional
Return Optional<T> for lookups that may find nothing.
Checked exceptions
throws clause with imports for qualified names.
Compilable stub
A default return value or UnsupportedOperationException.
When to use Java Method Generator
- Scaffolding service and repository methods.
- Writing utility methods with complete Javadoc.
- Standardising argument validation across a code base.
- Learning Java method conventions.
Java Method Generator FAQ
Why are parameters final?
It prevents reassigning a parameter by mistake inside the method, which makes the method easier to read. It does not affect callers.
When should a method return Optional?
When “no result” is a normal outcome, such as a lookup by e-mail. Optional makes callers handle the empty case. Do not use it for fields or parameters.
What do the null checks do?
Objects.requireNonNull throws NullPointerException with a message naming the parameter, right at the start of the method.
How are long types written?
Write long as the type to get long (or Long when the parameter may be null); int stays int.
What does the placeholder return?
A neutral value of the return type, such as 0, "", List.of() or Optional.empty(). For other object types it throws UnsupportedOperationException.
Is anything uploaded?
No. The method is generated in your browser.
Defensive, documented Java methods
A good Java method makes its contract explicit. The signature declares the types and checked exceptions, the Javadoc explains what each parameter means and what can go wrong, and the first lines of the body enforce the contract by rejecting invalid arguments. The generator writes all three parts consistently.
Parameters are entered with neutral types and become Java types: String, int, double, boolean, Instant, List and Map. Parameters marked as optional may be null and use boxed types where needed. Every parameter is declared final.
Validation follows the common conventions. Reference parameters that must not be null are checked with Objects.requireNonNull, which throws NullPointerException with a helpful message. Size-like integer parameters, such as limit or maxLength, are checked for negative values with IllegalArgumentException, and identifiers such as e-mail addresses are checked for blank strings. Each check is reflected in a @throws tag.
Return types can be wrapped in Optional for lookups, which is the idiomatic way to say “maybe no result” in modern Java. Checked exceptions are added to the throws clause; fully qualified names such as java.sql.SQLException are imported automatically and used by their simple name.
The method is placed inside a class declaration so that the output compiles as a file, and the body contains a TODO with a placeholder return value, so the code builds while you work on the implementation.