<分区>
初始起点
我有一个包含 1000 个 Person 对象的现有 List，我想插入一个 Extractor 来监听任何 中的属性变化>Person 对象(此 ObservableList 稍后将附加到 TableView)。
所以我的代码是这样的:
ObservableList<Person> observablePersons = FXCollections.observableList(personlist,
personextractor);
错误信息
但是当我尝试向这个 ObservableList observablePersons 添加一个新的 person 对象时，我遇到了这个错误:
run:
Exception in thread "main" java.lang.UnsupportedOperationException
at java.util.AbstractList.add(AbstractList.java:148)
at com.sun.javafx.collections.ObservableListWrapper.doAdd(ObservableListWrapper.java:101)
at javafx.collections.ModifiableObservableListBase.add(ModifiableObservableListBase.java:151)
at java.util.AbstractList.add(AbstractList.java:108)
at test.listchangelistener.listChangeDemo.main(listChangeDemo.java:72)
Java Result: 1
您能告诉我为什么会看到此错误消息吗？我的java版本是jdk1.8.0_91 (32-Bit)
人类
package test.listchangelistener;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
class Person {
private final IntegerProperty age = new SimpleIntegerProperty();
private final StringProperty name = new SimpleStringProperty();
public Person(String name, Integer age) {
setName(name);
setAge(age);
}
public int getAge() {
return age.get();
}
public final void setAge(int value) {
age.set(value);
}
public IntegerProperty ageProperty() {
return age;
}
public String getName() {
return name.get();
}
public final void setName(String value) {
name.set(value);
}
public StringProperty nameProperty() {
return name;
}
@Override
public String toString() {
return "Person{" + "age=" + age.get() + ", name=" + name.get() + '}';
}
}
测试代码
package test.listchangelistener;
import java.util.Arrays;
import java.util.List;
import javafx.beans.Observable;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.util.Callback;
public class listChangeDemo {
public static void main(String[] args) {
Person p1 = new Person("Ted", 26);
Person p2 = new Person("Anne", 19);
// just a simple list
List<Person> persons = Arrays.asList(p1, p2);
// extractor to observe change of person properties
Callback<Person, Observable[]> extractor = (Person p) -> {
return new Observable[]{
p.ageProperty(),
p.nameProperty()
};
};
// make list observable and attach extractor
ObservableList<Person> observablePersons = FXCollections.observableList(persons, extractor);
// create listchangeListener for observableList
ListChangeListener listener = (ListChangeListener) (ListChangeListener.Change c) -> {
while (c.next()) {
if (c.wasAdded()) {
System.out.println("these were added: ");
List addedSubList = c.getAddedSubList();
addedSubList.forEach((Object t) -> {
System.out.println("added Person: " + t);
});
} else if (c.wasRemoved()) {
System.out.println("these were removed");
List removedSubList = c.getRemoved();
removedSubList.forEach((Object t) -> {
System.out.println("removed Person: " + t);
});
} else if (c.wasUpdated()) {
System.out.println("these were updated");
System.out.println("Updated elements are: "
+ c.getList().subList(c.getFrom(), c.getTo()));
}
}
};
// attach listchangeListener to observableList
observablePersons.addListener(listener);
// testing changes
observablePersons.add(new Person("Siegfried", 10));
}
}