Joshua received his Bachelor of Laws degree from Universitas Gadjah Mada majoring in business law. During his studies, he participated in several student organizations and in national to international competitions. Joshua first took part in the Piala Dekan Fakultas Hukum Universitas Gadjah Mada Competition and won 3rd place in the Moot Court Competition. He also took part in the Soedarto VI National Moot Court Competition with the topic of Anti-Corruption Law in Indonesia and won 3rd place and some of the best categories and the 2019 Annual Foreign Direct Investment Moot held by Stockholm University Sweden. For his participation in these competitions, he received a certificate as one of the most outstanding students of Faculty of Law Universitas Gadjah Mada.