Going from Javanese to Sinhala (เทเทเถเทเถฝ) has a composite linguistic distance of 83% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Latin/Javanese โ Sinhala
Austronesian โ Indo-European
The 5 languages with the lowest linguistic distance from Javanese:
A quick 3-question check between Javanese and Sinhala. No signup.