应用程序 start() 方法中的 Javafx 绑定抛出异常
Javafx Binding throw exception in application start() method
UnsupportedOperationException 在将对象绑定到 TableView 时在 Bindings.bindContent() 中抛出。为什么？如何解决这个问题？
我正在使用 java 8 update181。
Exception in Application start method java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication4(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.UnsupportedOperationException
at java.util.AbstractList.remove(AbstractList.java:161)
at java.util.AbstractList$Itr.remove(AbstractList.java:374)
at java.util.AbstractList.removeRange(AbstractList.java:571)
at java.util.AbstractList.clear(AbstractList.java:234)
at com.sun.javafx.binding.ContentBinding.bind(ContentBinding.java:55)
at javafx.beans.binding.Bindings.bindContent(Bindings.java:1020)
at problem_bind.Main.start(Main.java:42)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication11(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait4(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null2(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater3(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null7(WinApplication.java:177)
... 1 more Exception running application problem_bind.Main
我的代码：
package problem_bind;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
House house = new House();
TableView<Person> table = new TableView<>();
table.setEditable(true);
TableColumn<Person, String> firstNameColumn = createColumn("First Name", "firstName");
TableColumn<Person, String> lastNameColumn = createColumn("Last Name", "lastName");
table.getColumns().add(firstNameColumn);
table.getColumns().add(lastNameColumn);
ObservableList<Person> data = FXCollections.observableArrayList();
data.addAll(house.getPersons());
table.setItems(data);
Bindings.bindContent(house.getPersons(), table.getItems());
BorderPane root = new BorderPane(table, null, null, null, null);
root.setPadding(new Insets(10));
primaryStage.setScene(new Scene(root, 600, 600));
primaryStage.show();
}
private TableColumn<Person, String> createColumn(String title, String property) {
TableColumn<Person, String> col = new TableColumn<>(title);
col.setSortable(false);
col.setCellValueFactory(
new PropertyValueFactory<Person, String>(property));
col.setCellFactory(TextFieldTableCell.forTableColumn());
return col ;
}
public static class House {
private List<Person> persons = new ArrayList<Person>();
public House() {
this.persons = Arrays.asList(
new Person("Jacob", "Smith", this),
new Person("Isabella", "Johnson", this),
new Person("Ethan", "Williams", this),
new Person("Emma", "Jones", this),
new Person("Michael", "Brown", this));
}
public List<Person> getPersons() {
return persons;
}
}
public static class Person {
private String firstName ;
private String lastName ;
private House house;
public Person(String firstName, String lastName, House house) {
this.firstName = firstName ;
this.lastName = lastName ;
this.house = house;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
}
问题出在您对 Arrays.asList(Object...) 的使用上。该方法：
Returns a fixed-size list backed by the specified array.
因此，返回的List不支持add或remove等操作。相反，您将通过 set 方法修改此类列表。前两种方法本质上需要一个可变大小的列表。 Bindings.bindContent 的实现显然在同步列表时尝试使用那些不受支持的方法。
改变这个：
this.persons = Arrays.asList(
new Person("Jacob", "Smith", this),
new Person("Isabella", "Johnson", this),
new Person("Ethan", "Williams", this),
new Person("Emma", "Jones", this),
new Person("Michael", "Brown", this));
为此：
persons = new ArrayList<>();
persons.add(new Person("Jacob", "Smith", this));
persons.add(new Person("Isabella", "Johnson", this));
persons.add(new Person("Ethan", "Williams", this));
persons.add(new Person("Emma", "Jones", this));
persons.add(new Person("Michael", "Brown", this));
注意：在您当前的代码中，前缀 this 是不必要的。但如果你愿意，你仍然可以使用它。
注 #2：参见 。
基本上，请确保使用支持 add 和 remove 操作的 List。
您可能想知道为什么首先调用 Bindings.bindContent(List,ObservableList) 会导致 remove 调用。这是因为那个方法 returns:
A content binding [ensuring] that the List contains the same elements as the ObservableList. If the content of the ObservableList changes, the List will be updated automatically.
换句话说，更新 List 以匹配 ObservableList。这涉及到在首次创建绑定时清除 List，然后将 ObservableList 的所有元素添加到其中。
UnsupportedOperationException 在将对象绑定到 TableView 时在 Bindings.bindContent() 中抛出。为什么？如何解决这个问题？
我正在使用 java 8 update181。
Exception in Application start method java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication4(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.UnsupportedOperationException
at java.util.AbstractList.remove(AbstractList.java:161)
at java.util.AbstractList$Itr.remove(AbstractList.java:374)
at java.util.AbstractList.removeRange(AbstractList.java:571)
at java.util.AbstractList.clear(AbstractList.java:234)
at com.sun.javafx.binding.ContentBinding.bind(ContentBinding.java:55)
at javafx.beans.binding.Bindings.bindContent(Bindings.java:1020)
at problem_bind.Main.start(Main.java:42)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication11(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait4(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null2(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater3(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null7(WinApplication.java:177)
... 1 more Exception running application problem_bind.Main
我的代码：
package problem_bind;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
House house = new House();
TableView<Person> table = new TableView<>();
table.setEditable(true);
TableColumn<Person, String> firstNameColumn = createColumn("First Name", "firstName");
TableColumn<Person, String> lastNameColumn = createColumn("Last Name", "lastName");
table.getColumns().add(firstNameColumn);
table.getColumns().add(lastNameColumn);
ObservableList<Person> data = FXCollections.observableArrayList();
data.addAll(house.getPersons());
table.setItems(data);
Bindings.bindContent(house.getPersons(), table.getItems());
BorderPane root = new BorderPane(table, null, null, null, null);
root.setPadding(new Insets(10));
primaryStage.setScene(new Scene(root, 600, 600));
primaryStage.show();
}
private TableColumn<Person, String> createColumn(String title, String property) {
TableColumn<Person, String> col = new TableColumn<>(title);
col.setSortable(false);
col.setCellValueFactory(
new PropertyValueFactory<Person, String>(property));
col.setCellFactory(TextFieldTableCell.forTableColumn());
return col ;
}
public static class House {
private List<Person> persons = new ArrayList<Person>();
public House() {
this.persons = Arrays.asList(
new Person("Jacob", "Smith", this),
new Person("Isabella", "Johnson", this),
new Person("Ethan", "Williams", this),
new Person("Emma", "Jones", this),
new Person("Michael", "Brown", this));
}
public List<Person> getPersons() {
return persons;
}
}
public static class Person {
private String firstName ;
private String lastName ;
private House house;
public Person(String firstName, String lastName, House house) {
this.firstName = firstName ;
this.lastName = lastName ;
this.house = house;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
}
问题出在您对 Arrays.asList(Object...) 的使用上。该方法：
Returns a fixed-size list backed by the specified array.
因此，返回的List不支持add或remove等操作。相反，您将通过 set 方法修改此类列表。前两种方法本质上需要一个可变大小的列表。 Bindings.bindContent 的实现显然在同步列表时尝试使用那些不受支持的方法。
改变这个：
this.persons = Arrays.asList(
new Person("Jacob", "Smith", this),
new Person("Isabella", "Johnson", this),
new Person("Ethan", "Williams", this),
new Person("Emma", "Jones", this),
new Person("Michael", "Brown", this));
为此：
persons = new ArrayList<>();
persons.add(new Person("Jacob", "Smith", this));
persons.add(new Person("Isabella", "Johnson", this));
persons.add(new Person("Ethan", "Williams", this));
persons.add(new Person("Emma", "Jones", this));
persons.add(new Person("Michael", "Brown", this));
注意：在您当前的代码中，前缀 this 是不必要的。但如果你愿意，你仍然可以使用它。
注 #2：参见
基本上，请确保使用支持 add 和 remove 操作的 List。
您可能想知道为什么首先调用 Bindings.bindContent(List,ObservableList) 会导致 remove 调用。这是因为那个方法 returns:
A content binding [ensuring] that the
Listcontains the same elements as theObservableList. If the content of theObservableListchanges, theListwill be updated automatically.
换句话说，更新 List 以匹配 ObservableList。这涉及到在首次创建绑定时清除 List，然后将 ObservableList 的所有元素添加到其中。