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ListTesting.javaAPI DocExample2233Fri Jul 05 16:11:46 BST 2002tuning.threads

ListTesting

public class ListTesting extends Object

Fields Summary
public static final int
CAPACITY
Constructors Summary
Methods Summary
public static voidmain(java.lang.String[] args)

      
  
    maintest(args);
    maintest(args);
public static voidmaintest(java.lang.String[] args)

    //In order to isolate the effects of synchronization, we make sure
    //that the garbage collector doesn't interfere with the test. So
    //we use a bunch of pre-allocated, pre-sized collections, and
    //populate those collections with pre-existing objects. No objects
    //will be created or released during the timing phase of the tests.
    List[] l = {new Vector(CAPACITY), new Vector(CAPACITY),
      new Vector(CAPACITY), new ArrayList(CAPACITY),
      new ArrayList(CAPACITY), new ArrayList(CAPACITY),
      Collections.synchronizedList(new ArrayList(CAPACITY)),
      Collections.synchronizedList(new ArrayList(CAPACITY)),
      Collections.synchronizedList(new ArrayList(CAPACITY))};
    int REPEAT = (args.length > 0) ? Integer.parseInt(args[0]) : 100;

    //Vary the order.
    test(l[0], REPEAT, "Vector");
    test(l[6], REPEAT, "sync ArrayList" );
    test(l[3], REPEAT, "ArrayList");
    test(l[1], REPEAT, "Vector");
    test(l[4], REPEAT, "ArrayList");
    test(l[7], REPEAT, "sync ArrayList" );
    test(l[2], REPEAT, "Vector");
    test(l[5], REPEAT, "ArrayList");
    test(l[8], REPEAT, "sync ArrayList" );
public static voidtest(java.util.List l, int REPEAT, java.lang.String ltype)

    //need to initialize for set() to work. Don't measure this time
    for (int j = 0; j < CAPACITY; j++)
      l.add(Boolean.FALSE);

    long time = System.currentTimeMillis();
    //The test sets elements repeatedly. The set methods are
    //very similar. Apart from synchronization, the Vector.set()
    //is slightly more efficient than the ArrayList.set(), which
    //is in turn more efficient than the wrapped ArrayList because
    //there is one extra layer of method calls for the wrapped object.
    for (int i = REPEAT; i > 0; i--)
      for (int j = 0; j < CAPACITY; j++)
        l.set(j, Boolean.TRUE);
    System.out.println(ltype + " took " +
        (System.currentTimeMillis()-time));