Jamieson, Fausset and Brown on 2 Kings 24:17-19

17-19. the king of Babylon made Mattaniah, his father's brother, king in his stead--Adhering to his former policy of maintaining a show of monarchy, Nebuchadnezzar appointed the third and youngest son of Josiah (1Ch 3:15), full brother of Jehoahaz, and uncle of the captive Jehoiachin. But, according to the custom of conquerors, who changed the names of the great men they took captives in war, in token of their supremacy, he gave him the new name of

Zedekiah--that is, "The righteous of God." This being a purely Hebrew name, it seems that he allowed the puppet king to choose his own name, which was confirmed. His heart towards God was the same as that of Jehoiakim, impenitent and heedless of God's word.