com.trolltech.qt.core
Class QFutureIterator

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QFutureIterator
All Implemented Interfaces:
QtJambiInterface

public class QFutureIterator
extends QtJambiObject

The QFutureIterator class provides a Java-style const iterator for QFuture. QFuture has both Java-style iterators and STL-style iterators. The Java-style iterators are more high-level and easier to use than the STL-style iterators; on the other hand, they are slightly less efficient.

An alternative to using iterators is to use index positions. Some QFuture member functions take an index as their first parameter, making it possible to access results without using iterators.

QFutureIterator<T> allows you to iterate over a QFuture<T>. Note that there is no mutable iterator for QFuture (unlike the other Java-style iterators).

The QFutureIterator constructor takes a QFuture as its argument. After construction, the iterator is located at the very beginning of the result list (i.e. before the first result). Here's how to iterate over all the results sequentially:

        QFuture<String> future = new QFuture<String>();
         ... 

        QFutureIterator<String> i = new QFutureIterator<String>(future);
        while (i.hasNext())
            System.out.println(i.next());
The next() function returns the next result (waiting for it to become available, if necessary) from the future and advances the iterator. Unlike STL-style iterators, Java-style iterators point between results rather than directly at results. The first call to next() advances the iterator to the position between the first and second result, and returns the first result; the second call to next() advances the iterator to the position between the second and third result, and returns the second result; and so on.

Here's how to iterate over the elements in reverse order:
        QFutureIterator<String> i = new QFutureIterator<String>(future);
        i.toBack();
        while (i.hasPrevious())
            System.out.println(i.previous());
If you want to find all occurrences of a particular value, use findNext() or findPrevious() in a loop.

Multiple iterators can be used on the same future. If the future is modified while a QFutureIterator is active, the QFutureIterator will continue iterating over the original future, ignoring the modified copy.

See also:
QFuture::const_iterator, and QFuture.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QFutureIterator(QFuture container)
          Constructs an iterator for traversing future.
 
Method Summary
 boolean findNext(java.lang.Object t)
          Searches for value starting from the current iterator position forward.
 boolean findPrevious(java.lang.Object t)
          Searches for value starting from the current iterator position backward.
 boolean hasNext()
          Returns true if there is at least one result ahead of the iterator, e.
 boolean hasPrevious()
          Returns true if there is at least one result ahead of the iterator, e.
 java.lang.Object next()
          Returns the next result and advances the iterator by one position.
 java.lang.Object peekNext()
          Returns the next result without moving the iterator.
 java.lang.Object peekPrevious()
          Returns the previous result without moving the iterator.
 java.lang.Object previous()
          Returns the previous result and moves the iterator back by one position.
 void toBack()
          Moves the iterator to the back of the result list (after the last result).
 void toFront()
          Moves the iterator to the front of the result list (before the first result).
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QFutureIterator

public QFutureIterator(QFuture container)
Constructs an iterator for traversing future. The iterator is set to be at the front of the result list (before the first result).

See also:
operator=().

Method Detail

findNext

public final boolean findNext(java.lang.Object t)
Searches for value starting from the current iterator position forward. Returns true if value is found; otherwise returns false.

After the call, if value was found, the iterator is positioned just after the matching result; otherwise, the iterator is positioned at the back of the result list.

See also:
findPrevious().


findPrevious

public final boolean findPrevious(java.lang.Object t)
Searches for value starting from the current iterator position backward. Returns true if value is found; otherwise returns false.

After the call, if value was found, the iterator is positioned just before the matching result; otherwise, the iterator is positioned at the front of the result list.

See also:
findNext().


hasNext

public final boolean hasNext()
Returns true if there is at least one result ahead of the iterator, e. ., the iterator is not at the back of the result list; otherwise returns false.

See also:
hasPrevious(), and next().


hasPrevious

public final boolean hasPrevious()
Returns true if there is at least one result ahead of the iterator, e. ., the iterator is not at the front of the result list; otherwise returns false.

See also:
hasNext(), and previous().


next

public final java.lang.Object next()
Returns the next result and advances the iterator by one position.

Calling this function on an iterator located at the back of the result list leads to undefined results.

See also:
hasNext(), peekNext(), and previous().


peekNext

public final java.lang.Object peekNext()
Returns the next result without moving the iterator.

Calling this function on an iterator located at the back of the result list leads to undefined results.

See also:
hasNext(), next(), and peekPrevious().


peekPrevious

public final java.lang.Object peekPrevious()
Returns the previous result without moving the iterator.

Calling this function on an iterator located at the front of the result list leads to undefined results.

See also:
hasPrevious(), previous(), and peekNext().


previous

public final java.lang.Object previous()
Returns the previous result and moves the iterator back by one position.

Calling this function on an iterator located at the front of the result list leads to undefined results.

See also:
hasPrevious(), peekPrevious(), and next().


toBack

public final void toBack()
Moves the iterator to the back of the result list (after the last result).

See also:
toFront(), and previous().


toFront

public final void toFront()
Moves the iterator to the front of the result list (before the first result).

See also:
toBack(), and next().