What are the methods for encrypting Java code?

There are several methods for encrypting Java code:

1. Symmetric encryption: Using the same key for both encryption and decryption, common symmetric encryption algorithms include AES, DES, and 3DES.
2. Asymmetric encryption: It involves using different keys for encryption and decryption. Common examples of asymmetric encryption algorithms include RSA and DSA.
3. Hash algorithm: converting data of any length into a fixed-length hash value, common hash algorithms include MD5, SHA-1, SHA-256, etc.
4. Digital signature: Combining asymmetric encryption and hashing algorithms to verify the integrity and origin of data, common digital signature algorithms include DSA, RSA, and others.
5. Code conversion: converting source code into an unreadable form, common methods of code conversion include Base64 encoding, URL encoding, etc.

It is necessary to choose the appropriate encryption method based on specific needs, which can be achieved by using either the built-in encryption library in Java or a third-party encryption library for different encryption functions.