What causes "not support .class value yet!" in pxb1988/dex2jar?

Exclude methods with .class LDC instructions from the -m config and target the core decryptor directly

pxb1988/dex2jar · error · RuntimeException

not support .class value yet!

Error message

not support .class value yet!

What it means

The string-decryption scanner evaluates constant-producing instructions to recover encrypted-string arguments. LDC pushing a Type constant (.class literal) is not a supported constant value, so it throws this RuntimeException.

Solutions

Exclude methods with .class LDC instructions from the -m config and target the core decryptor directly
Patch DecryptStringCmd to return the Type constant (e.g. return ldc.cst or a placeholder) instead of throwing
Use a newer dex2jar build if available; this limitation has been addressed in some forks

Example fix

// before
if (ldc.cst instanceof Type) { throw new RuntimeException("not support .class value yet!"); }
// after
if (ldc.cst instanceof Type) { return ((Type) ldc.cst).getClassName(); }

Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-scan target methods for Type LDC instructions
boolean hasClassLdc = method.instructions.stream()
    .anyMatch(insn -> insn instanceof LdcInsnNode && ((LdcInsnNode) insn).cst instanceof Type);

Try / catch

try { runDecryptScan(config); } catch (RuntimeException e) { if ("not support .class value yet!".equals(e.getMessage())) { skipMethodAndLog(); } else throw e; }

Prevention

Target the core string-decryptor method directly, avoiding helpers with .class literals
Filter candidate methods for Type LDCs before scanning
Fork/patch the scanner to treat Type constants as opaque values

When it happens

Trigger: The candidate decryptor method chain contains an LDC instruction loading a Class constant (e.g. `Foo.class`) inside the scanned method, hitting the `ldc.cst instanceof Type` check.

Common situations: Analyzing obfuscated code where the decryptor helper references .class literals for lookups, or modern bytecode patterns the tool predates.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of pxb1988/dex2jar@b5bda4fb49 (2026-09-08). Data as JSON: /api/errors/869c96422bc9be18. Report an issue: GitHub.

Appendix: source

Thrown at dex-tools/src/main/java/com/googlecode/dex2jar/tools/DecryptStringCmd.java:951

                Method m = findAnyMethodMatch(itf, name, classes);
                if (m != null) {
                    return m;
                }
            }
        }
        return null;
    }

    Object readCst(AbstractInsnNode q) {

        switch (q.getOpcode()) {
            case Opcodes.LDC:
                // LDC: String, integer, long and double cases (Opcodes.LDC comprehends LDC_W and LDC2_W)
                // push 32bit or 64bit int/float
                // push string/type
                LdcInsnNode ldc = (LdcInsnNode) q;
                if (ldc.cst instanceof Type) {
                    throw new RuntimeException("not support .class value yet!");
                }
                return ldc.cst;

            case Opcodes.BIPUSH:
            case Opcodes.SIPUSH:
                // INT_INSN ("instruction with a single int operand")
                // push 8bit or 16bit int
                IntInsnNode in = (IntInsnNode) q;
                return in.operand;

            case Opcodes.ICONST_M1:
            case Opcodes.ICONST_0:
            case Opcodes.ICONST_1:
            case Opcodes.ICONST_2:
            case Opcodes.ICONST_3:
            case Opcodes.ICONST_4:
            case Opcodes.ICONST_5:
                // ICONST_*: push a tiny int, -1 <= value <= 5

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