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When a developer uses an identifier that has the same name as a public class, such as {{Vector}}, a subsequent maintainer might be unaware that this identifier does not actually refer to {{java.util.Vector}} and might unintentionally use the custom {{Vector}} rather than the original {{java.util.Vector}} class. The custom type {{Vector}} can [shadow|BB. Glossary#shadow] a class name from {{java.util.Vector}}, as specified by the JLS, [&#xA7sect;6.3.2, "Obscured Declarations"|http://java.sun.com/docs/books/jls/third_edition/html/names.html#6.3.2] \[[JLS 2005|AA. References#JLS 05]\]. This can result in unexpected program behavior.

Well-defined import statements can resolve these issues. However, when reused name definitions are imported from other packages, use of the _type-import-on-demand declaration_ (see the JLS, [&#xA7sect;7.5.2, "Type-Import-on-Demand Declaration"|http://java.sun.com/docs/books/jls/third_edition/html/packages.html#7.5.2] \[[JLS 2005|AA. References#JLS 05]\]) can complicate a programmer's attempt to determine which specific definition was intended to be used. Additionally, a common practice that can lead to errors is to produce the import statements _after_ writing the code, often via automatic inclusion of import statements by an IDE. This creates further ambiguity with respect to the names. When a custom type is found earlier than the intended type in the Java include path, no further searches are conducted. Consequently, the wrong type is silently adopted.