skylot/jadx · error · JadxRuntimeException

Unknown output format

Error message

Unknown output format

What it means

Thrown by CodeGen.makeCode() as the default branch of the switch on args.getOutputFormat(). The OutputFormatEnum currently defines only JAVA and JSON. Reaching the default means a new output format constant was added to the enum without a corresponding case in this switch — a development-time guard against incomplete format support.

Source

Thrown at jadx-core/src/main/java/jadx/core/codegen/CodeGen.java:28

import jadx.core.dex.nodes.ClassNode;
import jadx.core.utils.exceptions.JadxRuntimeException;

public class CodeGen {

	public static ICodeInfo generate(ClassNode cls) {
		if (cls.contains(AFlag.DONT_GENERATE)) {
			return ICodeInfo.EMPTY;
		}
		JadxArgs args = cls.root().getArgs();
		switch (args.getOutputFormat()) {
			case JAVA:
				return generateJavaCode(cls, args);

			case JSON:
				return generateJson(cls);

			default:
				throw new JadxRuntimeException("Unknown output format");
		}
	}

	private static ICodeInfo generateJavaCode(ClassNode cls, JadxArgs args) {
		ClassGen clsGen = new ClassGen(cls, args);
		return wrapCodeGen(cls, clsGen::makeClass);
	}

	private static ICodeInfo generateJson(ClassNode cls) {
		JsonCodeGen codeGen = new JsonCodeGen(cls);
		String clsJson = wrapCodeGen(cls, codeGen::process);
		return new SimpleCodeInfo(clsJson);
	}

	private static <R> R wrapCodeGen(ClassNode cls, Callable<R> codeGenFunc) {
		try {
			return codeGenFunc.call();
		} catch (Exception e) {

View on GitHub (pinned to e738a26571)

Solutions

1. If adding a new OutputFormatEnum value, add a matching case in CodeGen.makeCode() that calls the appropriate generator.
2. Ensure the switch is exhaustive — consider using an exhaustive enum pattern or a map of OutputFormatEnum to generator functions.

Example fix

// before
//   switch (args.getOutputFormat()) {
//       case JAVA: ...
//       case JSON: ...
//       default: throw ...
//   }
// after
//       case KOTLIN: return generateKotlinCode(cls, args);

// Ensure only supported output formats are used
JadxArgs args = new JadxArgs();
OutputFormatEnum fmt = args.getOutputFormat();
if (fmt != OutputFormatEnum.JAVA && fmt != OutputFormatEnum.JSON) {
    throw new IllegalArgumentException("Unsupported output format: " + fmt);
}
// Only JAVA and JSON are currently supported by CodeGen

When it happens

Trigger: A new OutputFormatEnum constant (e.g., KOTLIN, SMALI) is added to JadxArgs but CodeGen.makeCode() is not updated with a matching case. Cannot occur with the currently shipped enum.

Common situations: Contributing a new output format to jadx and forgetting to add the generation branch. Forking jadx and adding an enum value without updating all switch sites.

Related errors

• Unknown condition mode:
• Unknown arg type
• Unknown instruction:
• Unknown loop type:
• Unexpected field type class:

AI-assisted analysis of skylot/jadx@e738a26571 (2026-08-14). Data as JSON: /api/errors/b230b69f278b7620. Report an issue: GitHub.