我所说的连接是指获得一个新列表，它监听所有连接部分的变化。
方法的目的是什么 FXCollections#concat(ObservableList<E>... lists) ？如果它只是合并几个列表，那么我认为为此使用单独的方法是没有意义的。
如果认为是在做我想做的事，那么它就不起作用了:
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
public class ConcatObservabeList {
public static void main(String[] args) {
ObservableList<Integer> list1 = FXCollections.observableArrayList();
ObservableList<Integer> list2 = FXCollections.observableArrayList();
ObservableList<Integer> concat = FXCollections.concat(list1, list2);
concat.addListener(new ListChangeListener<Integer>() {
public void onChanged(Change<? extends Integer> c) {
System.out.println("changed");
}
});
list1.add(12);
}
}
最佳答案
我同样需要将多个 ObservableList 连接/聚合到一个 JavaFX 折线图列表中。我在这里或在另一个答案中发布的 github 上找到的示例总是在每次更改时将子列表中的所有条目复制到聚合列表中。对于包含许多条目的列表，这似乎不是很优雅。
我决定实现我的 on 版本，它跟踪子列表在聚合列表中的位置，当子列表中的元素发生变化时，在聚合列表中应用相同的更改。仍有改进的余地(不使用委托(delegate)列表而是直接扩展 ObservableList，或者将事件从子列表触发到聚合列表并覆盖 getters 和迭代器 - 帮助将不胜感激)，但我想我发布了我的这里的版本，也许它可以帮助某人。
代码:
/**
* This class aggregates several other Observed Lists (sublists), observes changes on those sublists and applies those same changes to the
* aggregated list.
* Inspired by:
* - http://stackoverflow.com/questions/25705847/listchangelistener-waspermutated-block
* - http://stackoverflow.com/questions/37524662/how-to-concatenate-observable-lists-in-javafx
* - https://github.com/lestard/advanced-bindings/blob/master/src/main/java/eu/lestard/advanced_bindings/api/CollectionBindings.java
* Posted result on: http://stackoverflow.com/questions/37524662/how-to-concatenate-observable-lists-in-javafx
*/
public class AggregatedObservableArrayList<T> {
protected final List<ObservableList<T>> lists = new ArrayList<>();
final private List<Integer> sizes = new ArrayList<>();
final private List<InternalListModificationListener> listeners = new ArrayList<>();
final protected ObservableList<T> aggregatedList = FXCollections.observableArrayList();
public AggregatedObservableArrayList() {
}
/**
* The Aggregated Observable List. This list is unmodifiable, because sorting this list would mess up the entire bookkeeping we do here.
*
* @return an unmodifiable view of the aggregatedList
*/
public ObservableList<T> getAggregatedList() {
return FXCollections.unmodifiableObservableList(aggregatedList);
}
public void appendList(@NotNull ObservableList<T> list) {
assert !lists.contains(list) : "List is already contained: " + list;
lists.add(list);
final InternalListModificationListener listener = new InternalListModificationListener(list);
list.addListener(listener);
//System.out.println("list = " + list + " puttingInMap=" + list.hashCode());
sizes.add(list.size());
aggregatedList.addAll(list);
listeners.add(listener);
assert lists.size() == sizes.size() && lists.size() == listeners.size() :
"lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size() + " or not equal to listeners.size=" + listeners.size();
}
public void prependList(@NotNull ObservableList<T> list) {
assert !lists.contains(list) : "List is already contained: " + list;
lists.add(0, list);
final InternalListModificationListener listener = new InternalListModificationListener(list);
list.addListener(listener);
//System.out.println("list = " + list + " puttingInMap=" + list.hashCode());
sizes.add(0, list.size());
aggregatedList.addAll(0, list);
listeners.add(0, listener);
assert lists.size() == sizes.size() && lists.size() == listeners.size() :
"lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size() + " or not equal to listeners.size=" + listeners.size();
}
public void removeList(@NotNull ObservableList<T> list) {
assert lists.size() == sizes.size() && lists.size() == listeners.size() :
"lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size() + " or not equal to listeners.size=" + listeners.size();
final int index = lists.indexOf(list);
if (index < 0) {
throw new IllegalArgumentException("Cannot remove a list that is not contained: " + list + " lists=" + lists);
}
final int startIndex = getStartIndex(list);
final int endIndex = getEndIndex(list, startIndex);
// we want to find the start index of this list inside the aggregated List. End index will be start + size - 1.
lists.remove(list);
sizes.remove(index);
final InternalListModificationListener listener = listeners.remove(index);
list.removeListener(listener);
aggregatedList.remove(startIndex, endIndex + 1); // end + 1 because end is exclusive
assert lists.size() == sizes.size() && lists.size() == listeners.size() :
"lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size() + " or not equal to listeners.size=" + listeners.size();
}
/**
* Get the start index of this list inside the aggregated List.
* This is a private function. we can safely asume, that the list is in the map.
*
* @param list the list in question
* @return the start index of this list in the aggregated List
*/
private int getStartIndex(@NotNull ObservableList<T> list) {
int startIndex = 0;
//System.out.println("=== searching startIndex of " + list);
assert lists.size() == sizes.size() : "lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size();
final int listIndex = lists.indexOf(list);
for (int i = 0; i < listIndex; i++) {
final Integer size = sizes.get(i);
startIndex += size;
//System.out.println(" startIndex = " + startIndex + " added=" + size);
}
//System.out.println("startIndex = " + startIndex);
return startIndex;
}
/**
* Get the end index of this list inside the aggregated List.
* This is a private function. we can safely asume, that the list is in the map.
*
* @param list the list in question
* @param startIndex the start of the list (retrieve with {@link #getStartIndex(ObservableList)}
* @return the end index of this list in the aggregated List
*/
private int getEndIndex(@NotNull ObservableList<T> list, int startIndex) {
assert lists.size() == sizes.size() : "lists.size=" + lists.size() + " not equal to sizes.size=" + sizes.size();
final int index = lists.indexOf(list);
return startIndex + sizes.get(index) - 1;
}
private class InternalListModificationListener implements ListChangeListener<T> {
@NotNull
private final ObservableList<T> list;
public InternalListModificationListener(@NotNull ObservableList<T> list) {
this.list = list;
}
/**
* Called after a change has been made to an ObservableList.
*
* @param change an object representing the change that was done
* @see Change
*/
@Override
public void onChanged(Change<? extends T> change) {
final ObservableList<? extends T> changedList = change.getList();
final int startIndex = getStartIndex(list);
final int index = lists.indexOf(list);
final int newSize = changedList.size();
//System.out.println("onChanged for list=" + list + " aggregate=" + aggregatedList);
while (change.next()) {
final int from = change.getFrom();
final int to = change.getTo();
//System.out.println(" startIndex=" + startIndex + " from=" + from + " to=" + to);
if (change.wasPermutated()) {
final ArrayList<T> copy = new ArrayList<>(aggregatedList.subList(startIndex + from, startIndex + to));
//System.out.println(" permutating sublist=" + copy);
for (int oldIndex = from; oldIndex < to; oldIndex++) {
int newIndex = change.getPermutation(oldIndex);
copy.set(newIndex - from, aggregatedList.get(startIndex + oldIndex));
}
//System.out.println(" permutating done sublist=" + copy);
aggregatedList.subList(startIndex + from, startIndex + to).clear();
aggregatedList.addAll(startIndex + from, copy);
} else if (change.wasUpdated()) {
// do nothing
} else {
if (change.wasRemoved()) {
List<? extends T> removed = change.getRemoved();
//System.out.println(" removed= " + removed);
// IMPORTANT! FROM == TO when removing items.
aggregatedList.remove(startIndex + from, startIndex + from + removed.size());
}
if (change.wasAdded()) {
List<? extends T> added = change.getAddedSubList();
//System.out.println(" added= " + added);
//add those elements to your data
aggregatedList.addAll(startIndex + from, added);
}
}
}
// update the size of the list in the map
//System.out.println("list = " + list + " puttingInMap=" + list.hashCode());
sizes.set(index, newSize);
//System.out.println("listSizesMap = " + sizes);
}
}
public String dump(Function<T, Object> function) {
StringBuilder sb = new StringBuilder();
sb.append("[");
aggregatedList.forEach(el -> sb.append(function.apply(el)).append(","));
final int length = sb.length();
sb.replace(length - 1, length, "");
sb.append("]");
return sb.toString();
}
}
jUnit 测试:
/**
* Testing the AggregatedObservableArrayList
*/
public class AggregatedObservableArrayListTest {
@Test
public void testObservableValue() {
final AggregatedObservableArrayList<IntegerProperty> aggregatedWrapper = new AggregatedObservableArrayList<>();
final ObservableList<IntegerProperty> aggregatedList = aggregatedWrapper.getAggregatedList();
aggregatedList.addListener((Observable observable) -> {
System.out.println("observable = " + observable);
});
final ObservableList<IntegerProperty> list1 = FXCollections.observableArrayList();
final ObservableList<IntegerProperty> list2 = FXCollections.observableArrayList();
final ObservableList<IntegerProperty> list3 = FXCollections.observableArrayList();
list1.addAll(new SimpleIntegerProperty(1), new SimpleIntegerProperty(2), new SimpleIntegerProperty(3), new SimpleIntegerProperty(4),
new SimpleIntegerProperty(5));
list2.addAll(new SimpleIntegerProperty(10), new SimpleIntegerProperty(11), new SimpleIntegerProperty(12), new SimpleIntegerProperty(13),
new SimpleIntegerProperty(14), new SimpleIntegerProperty(15));
list3.addAll(new SimpleIntegerProperty(100), new SimpleIntegerProperty(110), new SimpleIntegerProperty(120), new SimpleIntegerProperty(130),
new SimpleIntegerProperty(140), new SimpleIntegerProperty(150));
// adding list 1 to aggregate
aggregatedWrapper.appendList(list1);
assertEquals("wrong content", "[1,2,3,4,5]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// removing elems from list1
list1.remove(2, 4);
assertEquals("wrong content", "[1,2,5]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// adding second List
aggregatedWrapper.appendList(list2);
assertEquals("wrong content", "[1,2,5,10,11,12,13,14,15]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// removing elems from second List
list2.remove(1, 3);
assertEquals("wrong content", "[1,2,5,10,13,14,15]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// replacing element in first list
list1.set(1, new SimpleIntegerProperty(3));
assertEquals("wrong content", "[1,3,5,10,13,14,15]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// adding third List
aggregatedWrapper.appendList(list3);
assertEquals("wrong content", "[1,3,5,10,13,14,15,100,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// emptying second list
list2.clear();
assertEquals("wrong content", "[1,3,5,100,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// adding new elements to second list
list2.addAll(new SimpleIntegerProperty(203), new SimpleIntegerProperty(202), new SimpleIntegerProperty(201));
assertEquals("wrong content", "[1,3,5,203,202,201,100,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// sorting list2. this results in permutation
list2.sort((o1, o2) -> o1.getValue().compareTo(o2.getValue()));
assertEquals("wrong content", "[1,3,5,201,202,203,100,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// removing list2 completely
aggregatedWrapper.removeList(list2);
assertEquals("wrong content", "[1,3,5,100,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// updating one integer value in list 3
SimpleIntegerProperty integer = (SimpleIntegerProperty) list3.get(0);
integer.set(1);
assertEquals("wrong content", "[1,3,5,1,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
// prepending list 2 again
aggregatedWrapper.prependList(list2);
assertEquals("wrong content", "[201,202,203,1,3,5,1,110,120,130,140,150]", aggregatedWrapper.dump(ObservableIntegerValue::get));
}
}
关于java - 如何连接 JavaFX 中的可观察列表？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37524662/