FileDocCategorySizeDatePackage
ForInTester.javaAPI DocExample3892Sat Apr 24 08:24:26 BST 2004com.oreilly.tiger.ch07

ForInTester

public class ForInTester extends Object

Fields Summary
Constructors Summary
public ForInTester()
Methods Summary
public voiddetermineListPosition(java.io.PrintStream out, java.lang.String[] args)

Show list position in a loop (not possible with for/in)


    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);
public java.util.ListgetList()

    List list = new LinkedList();

    for (int i = 1; i <= 100; i++) {
      list.add("Item " + i);
    }

    return list;
public static voidmain(java.lang.String[] args)

    try {
      ForInTester tester = new ForInTester();

      tester.testForLoop(System.out);
      tester.testForInLoop(System.out);

      tester.testArrayLooping(System.out);
      tester.testObjectArrayLooping(System.out);

      tester.determineListPosition(System.out, args);
      tester.removeListItems(System.out, args);
      
    } catch (Exception e) {
      e.printStackTrace();
    }
public voidremoveListItems(java.io.PrintStream out, java.lang.String[] args)

for/in can't remove items using an Iterator


    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 voidtestArrayLooping(java.io.PrintStream out)

Test a simple array iteration

    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);
    }
public voidtestForInLoop(java.io.PrintStream out)

Test a very basic, Java 1.5 for/in loop

    List list = getList(); // initialize this list elsewhere

    for (Object listElement : list) {
      out.println(listElement.toString());

      // Do something else with this list object
    }
public voidtestForLoop(java.io.PrintStream out)

Test a very basic, pre-Java 1.5 for loop

    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
    }
public voidtestObjectArrayLooping(java.io.PrintStream out)

Test an object array iteration

    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());
    }