AESCrypt-Android | Simple API to perform AES encryption on Android. This is the Android counterpart to the AESCrypt lib | Encryption library

There are multiple issues with your code and you are missing some critical information (you may ask from the system sending data)

You are missing Cipher, IV (optionally) and key

Cipher c = Cipher.getInstance("AES");

Using only AES cipher with no IV parameter means you are using AES/ECB/PKCS5Padding cipher. Are you sure you suppose to use this cipher? Shouldn't it be AES/CBC/PKCS5Padding ? Ask the system doing the encryption what the encryption should be (including mode and padding). Knowing it's AES may not be sufficient.

If the mode used needs IV (initialization vector), you need to know its value. Usually IV is 128 bits (16 bytes) prepended to the ciphertext, but you need to know that for sure.

String salt = "PRUEBA";
SecretKeySpec key = new SecretKeySpec(salt.getBytes(), "AES");

And - you need a key (without the key you won't decrypt).

As already commented, the key needs to be 128, 192 or 256 bits long (=16, 24 or 32 bytes). If it is to be generated from another string, you need to know how.

String decryptedValue = new String(decValue);
String decoded=new String(Base64.decode(decryptedValue,Base64.DEFAULT));

Are you sure that the decrypted value is base64 encoding of another String?

Just to get some examples for Java crypto, you may have a loot at my blog too.

if it is encrypted by AES it should be decrypted by AES . i think there are built in functions for that aes_encrypt() and aes_decrypt()