The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进,并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要,请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息,请参阅JDK发行说明。
Sometimes, a query might produce too many answers and you want to limit the number of answers returned. You can do this by using the count limit search control. By default, a search does not have a count limit—it will return all answers that it finds. To set the count limit of a search, pass the number to SearchControls.setCountLimit().
The following example
sets the count limit to 1.
// Set the search controls to limit the count to 1 SearchControls ctls = new SearchControls(); ctls.setCountLimit(1);
If the program attempts to get more than the count limit number of results, then a SizeLimitExceededException will be thrown. So if a program has set a count limit, then it should either differentiate this exception from other NamingExceptions or keep track of the count limit and not request more than that number of results.
Specifying a count limit for a search is one way of controlling the resources (such as memory and network bandwidth) that your application consumes. Other ways to control the resources consumed are to narrow your search filter (be more specific about what you seek), start your search in the appropriate context, and use the appropriate scope.