Java for In(forin) Tester
/*
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.io.IOException;
import java.io.PrintStream;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
public class ForInTester {
public ForInTester() {
}
public List getList() {
List list = new LinkedList();
for (int i = 1; i <= 100; i++) {
list.add("Item " + i);
}
return list;
}
/**
* <p>Test a very basic, pre-Java 1.5 for loop</p>
*/
public void testForLoop(PrintStream out) throws IOException {
List list = getList(); // initialize this list elsewhere
for (Iterator i = list.iterator(); i.hasNext(); ) {
Object listElement = i.next();
out.println(listElement.toString());
// Do something else with this list object
}
}
/**
* <p>Test a very basic, Java 1.5 for/in loop</p>
*/
public void testForInLoop(PrintStream out) throws IOException {
List list = getList(); // initialize this list elsewhere
for (Object listElement : list) {
out.println(listElement.toString());
// Do something else with this list object
}
}
/**
* <p>Test a simple array iteration</p>
*/
public void testArrayLooping(PrintStream out) throws IOException {
int[] primes = new int[] { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 };
// Print the primes out using a for/in loop
for (int n : primes) {
out.println(n);
}
}
/**
* <p>Test an object array iteration</p>
*/
public void testObjectArrayLooping(PrintStream out) throws IOException {
List[] list_array = new List[3];
list_array[0] = getList();
list_array[1] = getList();
list_array[2] = getList();
for (List l : list_array) {
out.println(l.getClass().getName());
}
}
/**
* <p>Show list position in a loop (not possible with for/in)</p>
*/
public void determineListPosition(PrintStream out, String[] args)
throws IOException {
List<String> wordList = new LinkedList<String>();
// Impossible to assign the words, since the iterator is used
for (int i=0; i<args.length; i++) {
wordList.add("word " + (i+1) + ": '" + args[i] + "'");
}
// You can print the words using for/in, but not assign them
for (String word : wordList) {
out.println(word);
}
StringBuffer longList = new StringBuffer();
for (int i = 0, len=wordList.size(); i < len; i++) {
if (i < (len-1)) {
longList.append(wordList.get(i))
.append(", ");
} else {
longList.append(wordList.get(i));
}
}
out.println(longList);
}
/**
* <p>for/in can't remove items using an Iterator</p>
*/
public void removeListItems(PrintStream out, String[] args)
throws IOException {
List<String> wordList = new LinkedList<String>();
// Assign some words
for (int i=0; i<args.length; i++) {
wordList.add("word " + (i+1) + ": '" + args[i] + "'");
}
// Remove all words with "1" in them. Impossible with for/in
for (Iterator i = wordList.iterator(); i.hasNext(); ) {
String word = (String)i.next();
if (word.indexOf("1") != -1) {
i.remove();
}
}
// You can print the words using for/in
for (String word : wordList) {
out.println(word);
}
}
public static void main(String[] args) {
try {
String[] s = new String[]{"a","b","c"};
ForInTester tester = new ForInTester();
tester.testForLoop(System.out);
tester.testForInLoop(System.out);
tester.testArrayLooping(System.out);
tester.testObjectArrayLooping(System.out);
tester.determineListPosition(System.out, s);
tester.removeListItems(System.out, s);
} catch (Exception e) {
e.printStackTrace();
}
}
}
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