ProGuard doesn't obfuscate string constants, as mentioned in its FAQ. Its more recent specialized closed-source sibling for Android, DexGuard, provides additional application protection techniques, like string encryption and class encryption.
(I am the developer of ProGuard and DexGuard)
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…