The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
Instead of getting a single object at a time, as with Context.lookup() , you can list an entire context by using a single operation. There are two methods for listing a context: one that returns the bindings and one that returns only the name-to-object class name pairs.
Context.list() returns an enumeration of NameClassPair. Each NameClassPair consists of the object's name and its class name. The following code fragment lists the contents of the "ou=People" directory (that is, the files and directories found in "ou=People" directory).
NamingEnumeration list = ctx.list("ou=People"); while (list.hasMore()) { NameClassPair nc = (NameClassPair)list.next(); System.out.println(nc); }
Running
this example
yields the following output.
# java List cn=Jon Ruiz: javax.naming.directory.DirContext cn=Scott Seligman: javax.naming.directory.DirContext cn=Samuel Clemens: javax.naming.directory.DirContext cn=Rosanna Lee: javax.naming.directory.DirContext cn=Maxine Erlund: javax.naming.directory.DirContext cn=Niels Bohr: javax.naming.directory.DirContext cn=Uri Geller: javax.naming.directory.DirContext cn=Colleen Sullivan: javax.naming.directory.DirContext cn=Vinnie Ryan: javax.naming.directory.DirContext cn=Rod Serling: javax.naming.directory.DirContext cn=Jonathan Wood: javax.naming.directory.DirContext cn=Aravindan Ranganathan: javax.naming.directory.DirContext cn=Ian Anderson: javax.naming.directory.DirContext cn=Lao Tzu: javax.naming.directory.DirContext cn=Don Knuth: javax.naming.directory.DirContext cn=Roger Waters: javax.naming.directory.DirContext cn=Ben Dubin: javax.naming.directory.DirContext cn=Spuds Mackenzie: javax.naming.directory.DirContext cn=John Fowler: javax.naming.directory.DirContext cn=Londo Mollari: javax.naming.directory.DirContext cn=Ted Geisel: javax.naming.directory.DirContext
Context.listBindings() returns an enumeration of Binding. Binding is a subclass of NameClassPair. A binding contains not only the object's name and class name, but also the object. The following code enumerates the "ou=People" context, printing out each binding's name and object.
NamingEnumeration bindings = ctx.listBindings("ou=People"); while (bindings.hasMore()) { Binding bd = (Binding)bindings.next(); System.out.println(bd.getName() + ": " + bd.getObject()); }
Running
this example
yields the following output.
# java ListBindings cn=Jon Ruiz: com.sun.jndi.ldap.LdapCtx@1d4c61c cn=Scott Seligman: com.sun.jndi.ldap.LdapCtx@1a626f cn=Samuel Clemens: com.sun.jndi.ldap.LdapCtx@34a1fc cn=Rosanna Lee: com.sun.jndi.ldap.LdapCtx@176c74b cn=Maxine Erlund: com.sun.jndi.ldap.LdapCtx@11b9fb1 cn=Niels Bohr: com.sun.jndi.ldap.LdapCtx@913fe2 cn=Uri Geller: com.sun.jndi.ldap.LdapCtx@12558d6 cn=Colleen Sullivan: com.sun.jndi.ldap.LdapCtx@eb7859 cn=Vinnie Ryan: com.sun.jndi.ldap.LdapCtx@12a54f9 cn=Rod Serling: com.sun.jndi.ldap.LdapCtx@30e280 cn=Jonathan Wood: com.sun.jndi.ldap.LdapCtx@16672d6 cn=Aravindan Ranganathan: com.sun.jndi.ldap.LdapCtx@fd54d6 cn=Ian Anderson: com.sun.jndi.ldap.LdapCtx@1415de6 cn=Lao Tzu: com.sun.jndi.ldap.LdapCtx@7bd9f2 cn=Don Knuth: com.sun.jndi.ldap.LdapCtx@121cc40 cn=Roger Waters: com.sun.jndi.ldap.LdapCtx@443226 cn=Ben Dubin: com.sun.jndi.ldap.LdapCtx@1386000 cn=Spuds Mackenzie: com.sun.jndi.ldap.LdapCtx@26d4f1 cn=John Fowler: com.sun.jndi.ldap.LdapCtx@1662dc8 cn=Londo Mollari: com.sun.jndi.ldap.LdapCtx@147c5fc cn=Ted Geisel: com.sun.jndi.ldap.LdapCtx@3eca90
A NamingEnumeration can be terminated in one of three ways: naturally, explicitly, or unexpectedly.
Regardless of how an enumeration has been terminated, once terminated it can no longer be used. Invoking a method on a terminated enumeration yields an undefined result.
list() is intended for browser-style applications that just want to display the names of objects in a context. For example, a browser might list the names in a context and wait for the user to select one or a few of the names displayed to perform further operations. Such applications typically do not need access to all of the objects in a context.
listBindings() is intended for applications that need to perform operations on the objects in a context en masse. For example, a backup application might need to perform "file stats" operations on all of the objects in a file directory. Or a printer administration program might want to restart all of the printers in a building. To perform such operations, these applications need to obtain all of the objects bound in a context. Thus it is more expedient to have the objects returned as part of the enumeration.
The application can use either list() or the potentially more expensive listBindings(), depending on the type of information it needs.