In this paper, we present a Java-based framework for supporting the development of music-related software, called the Crest Muse Toolkit. Although various efficient software for dataflow visual programming of sound and music processing have been developed, they are not necessarily suitable for exploiting conventional programming skills and experience. Our toolkit has an datallow-paradigm-based but non-visual programming environment that has been carefully designed from an object-oriented point of view. By using this tookit, one can develop music-related software smoothly and efficiently.