Mega Code Archive
Java for in (forin) with generic Collection
<![CDATA[
/*
License for Java 1.5 'Tiger': A Developer's Notebook
(O'Reilly) example package
Java 1.5 'Tiger': A Developer's Notebook (O'Reilly)
by Brett McLaughlin and David Flanagan.
ISBN: 0-596-00738-8
You can use the examples and the source code any way you want, but
please include a reference to where it comes from if you use it in
your own products or services. Also note that this software is
provided by the author "as is", with no expressed or implied warranties.
In no event shall the author be liable for any direct or indirect
damages arising in any way out of the use of this software.
*/
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class ForInGenericsDemo {
public static void main(String[] args) {
// These are collections we'll iterate over below.
List<String> wordlist = new ArrayList<String>();
Set<String> wordset = new HashSet<String>();
// We start with a basic loop over the elements of an array.
// The body of the loop is executed once for each element of args[].
// Each time through one element is assigned to the variable word.
System.out.println("Assigning arguments to lists...");
for(String word : args) {
System.out.print(word + " ");
wordlist.add(word);
wordset.add(word);
}
System.out.println();
// Iterate through the elements of the List now.
// Since lists have an order, these words should appear as above
System.out.println("Printing words from wordlist " +
"(ordered, with duplicates)...");
for(String word : wordlist) {
System.out.print(word + " ");
}
System.out.println();
// Do the same for the Set. The loop looks the same but by virtue of
// using a Set, we lose the word order and also discard duplicates.
System.out.println("Printing words from wordset " +
"(unordered, no duplicates)...");
for(String word : wordset) {
System.out.print(word + " ");
}
}
}
]]>