A few years ago I wrote a Soduko solver in Java. Works great, except I have to edit the source file to change the input because I could never get Swing to work like my mental model said it should.

The empty quotes make the Scanner chunk out the line one char at ... To complete the use case, you must convert this one-character String into a single Java char with the charAt(0) method. Notice that ...

The Java printf function makes it easier to create informative strings of text without using String concatenation, or relying on non-standard characters that might trigger output errors. The easiest ...