Java Reference
In-Depth Information
Listing 3-14. Using the [ ] Operator with a List or an Array
someArray["1"]
someArray[1]
someList["2"]
someList[2]
For example, the array in Listing 3-15 can be accessed as illustrated in Listing 3-16.
Listing 3-15. Setting an Array as an Attribute in the Servlet Code
1. String [ ] books = {"Clojure", "Groovy ", "Java" , "Scala"} ;
2. request.setAttribute("books", books);
Listing 3-16. Using the [ ] Operator
Book: ${books[0]}
The output displayed for Listing 3-16 is as follows:
Book: Clojure
Note
Lists can be accessed in the same manner as arrays.
If there is a String literal inside the brackets of the [ ] operator, the variable to which the [ ] operator
is applied is either a JavaBean or a Map. Listing 3-17 illustrates the code for setting a Map as an
attribute in the Servlet.
Listing 3-17. Code Fragment for Setting a Map as an Attribute in the Servlet Code
1.Map<String, String> bookMap = new HashMap<>();
2.bookMap.put("Groovy", "Beginning Groovy");
3.bookMap.put("Java", " Beginning Java");
4.bookMap.put("Scala", " Beginning Scala");
5.request.setAttribute("books", bookMap);
In Listing 3-18, EL searches for the attribute bound to the name
books
in the scope. In Listing 3-17,
books is
a Map set in the
request
attribute. Therefore, EL searches for the key
Groovy
passed in the
[ ] operator of Listing 3-18 and evaluates it.
Listing 3-18. Using the [ ] Operator
Book : ${books["Groovy"] }
The output displayed for Listing 3-8 is as shown here:
Book: Beginning Groovy
