Jarhoo
Jarhoo provides a lookup service allowing developers to find jar file details for classes causing NoClassDefFoundError or ClassNotFoundException problems. The database is growing incrementally as more and more developers use the site - the most popular jar files are added on each database population. Also useful for those new to Java, Jarhoo can help developers write import statements by providing fully qualified class names for classes in its database, which can then be pasted into code.