HexView is a Java 1.4 graphical (GUI) application to display the contents of a file in hexadecimal and as plain text (7-bit ASCII). Files may be very large. Editing and searching are not supported.

CharMap is a Java 5.0 graphical (GUI) application to display Unicode characters or glyphs in text fonts, and copy those characters to the system clipboard. Its major purpose is as a visual accessory ...

Even though the introduction of Unicode technically solved this problem, you can still encounter situations in which some or all of your Unicode characters will not display properly in Java programs.