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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QFutureIterator<T>
public class QFutureIterator<T>
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:
The following code example is written in c++.
QFuture<QString> future; ... QFutureIterator<QString> i(future); while (i.hasNext()) qDebug() << 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. QFutureIterator<QString> i(future); i.toBack(); while (i.hasPrevious()) qDebug() << 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.
QFuture
.
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.QtJambiObject |
---|
QtJambiObject.QPrivateConstructor |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Constructor Summary | |
---|---|
|
QFutureIterator(QFuture<T> container)
Constructs an iterator for traversing future. |
protected |
QFutureIterator(QtJambiObject.QPrivateConstructor p)
This method is internal to Qt Jambi. |
Method Summary | |
---|---|
boolean |
findNext(T t)
Searches for value starting from the current iterator position forward. |
boolean |
findPrevious(T t)
Searches for value starting from the current iterator position backward. |
static QFutureIterator |
fromNativePointer(QNativePointer nativePointer)
|
boolean |
hasNext()
Returns true if there is at least one result ahead of the iterator, e.g., the iterator is not at the back of the result list; otherwise returns false. |
boolean |
hasPrevious()
Returns true if there is at least one result ahead of the iterator, e.g., the iterator is not at the front of the result list; otherwise returns false. |
T |
next()
Returns the next result and advances the iterator by one position. |
T |
peekNext()
Returns the next result without moving the iterator. |
T |
peekPrevious()
Returns the previous result without moving the iterator. |
T |
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 |
---|
disableGarbageCollection, dispose, disposed, equals, finalize, nativeId, nativePointer, reassignNativeResources, reenableGarbageCollection, setJavaOwnership, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
__qt_signalInitialization, blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class java.lang.Object |
---|
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
public QFutureIterator(QFuture<T> container)
protected QFutureIterator(QtJambiObject.QPrivateConstructor p)
Method Detail |
---|
public final boolean findNext(T t)
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.
findPrevious()
.
public final boolean findPrevious(T t)
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.
findNext()
.
public final boolean hasNext()
hasPrevious()
, and next()
.
public final boolean hasPrevious()
hasNext()
, and previous()
.
public final T next()
Calling this function on an iterator located at the back of the result list leads to undefined results.
hasNext()
, peekNext()
, and previous()
.
public final T peekNext()
Calling this function on an iterator located at the back of the result list leads to undefined results.
hasNext()
, next()
, and peekPrevious()
.
public final T peekPrevious()
Calling this function on an iterator located at the front of the result list leads to undefined results.
hasPrevious()
, previous()
, and peekNext()
.
public final T previous()
Calling this function on an iterator located at the front of the result list leads to undefined results.
hasPrevious()
, peekPrevious()
, and next()
.
public final void toBack()
toFront()
, and previous()
.
public final void toFront()
toBack()
, and next()
.
public static QFutureIterator fromNativePointer(QNativePointer nativePointer)
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