The java.io package’s String Reader class can be used to read data (in characters) from strings. It is an extension of the abstract class Reader. Note: In StringReader, the provided string serves as a source from which individual characters are read. We utilize a reader When we read character-based data from a data source. When we want to write character-based data, we utilize a writer. If we have a stream of bytes and wish to read characters by having those bytes decoded, we should use the InputStreamReader class.