Problem I want to add custom made panels, built via javafx scene builder, to a gridpane at runtime. My custom made panel exsits of buttons, labels and so on.
My Attempt I tried to extend from pane...
public class Celli extends Pane{
public Celli() throws IOException{
Parent root = FXMLLoader.load(getClass().getResource("Cell.fxml"));
this.getChildren().add(root);
}
}
... and then use this panel in the adding method of the conroller
@FXML
private void textChange(KeyEvent event) {
GridPane g = new GridPane();
for (int i=0 : i<100; i++){
g.getChildren().add(new Celli());
}
}
}
It works, but it performs very very poor.
What I am looking for Is there a way to design panels via javafx scene builder (and as a result having this panels in fxml) and then add it to a gridpane at runtime without make use of this fxmlloader for each instance. I think it performs poor because of the fxml loader. When I add a standard button e.g. whitout fxml it is very much faster.
This feature exists in the JavaFX Scene Builder by right clicking on the GridPane and selecting GridPane, then it will show a list of options: Add Row Above, Add Row Below, Add Column After, Add Column Before. The results of each of these options are what I desire.
I have had a similar issue. I also had to load a custom fxml-based component several times, dynamically, and it was taking too long. The FXMLLoader.load method call was expensive, in my case.
My approach was to parallelize the component instantiation and it solved the problem.
Considering the example posted on the question, the controller method with multithread approach would be:
private void textChange(KeyEvent event) {
GridPane g = new GridPane();
// creates a thread pool with 10 threads
ExecutorService threadPool = Executors.newFixedThreadPool(10);
final List<Celli> listOfComponents = Collections.synchronizedList(new ArrayList<Celli>(100));
for (int i = 0; i < 100; i++) {
// parallelizes component loading
threadPool.execute(new Runnable() {
@Override
public void run() {
listOfComponents.add(new Celli());
}
});
}
// waits until all threads completion
try {
threadPool.shutdown();
threadPool.awaitTermination(3, TimeUnit.SECONDS);
} catch (InterruptedException e) {
// seems to be a improbable exception, but we have to deal with it
e.printStackTrace();
}
g.getChildren().addAll(listOfComponents);
}
Short answer: No, it is not (as of JavaFX 2.x and 8.0). It may be in a future version (JFX >8)
Long answer: The FXMLLoader is currently not designed to perform as a template provider that instantiates the same item over and over again. Rather it is meant to be a one-time-loader for large GUIs (or to serialize them).
The performance is poor because depending on the FXML file, on each call to load()
, the FXMLLoader has to look up the classes and its properties via reflection. That means:
There is also currently no improvement for subsequent calls to load()
to the same FXML file done in the code. This means: no caching of found classes, no caching of BeanAdapters and so on.
There is a workaround for the performance of step 1, though, by setting a custom classloader to the FXMLLoader instance:
import java.io.IOException;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
public class MyClassLoader extends ClassLoader{
private final Map<String, Class> classes = new HashMap<String, Class>();
private final ClassLoader parent;
public MyClassLoader(ClassLoader parent) {
this.parent = parent;
}
@Override
public Class<?> loadClass(String name) throws ClassNotFoundException {
Class<?> c = findClass(name);
if ( c == null ) {
throw new ClassNotFoundException( name );
}
return c;
}
@Override
protected Class<?> findClass( String className ) throws ClassNotFoundException {
// System.out.print("try to load " + className);
if (classes.containsKey(className)) {
Class<?> result = classes.get(className);
return result;
} else {
try {
Class<?> result = parent.loadClass(className);
// System.out.println(" -> success!");
classes.put(className, result);
return result;
} catch (ClassNotFoundException ignore) {
// System.out.println();
classes.put(className, null);
return null;
}
}
}
// ========= delegating methods =============
@Override
public URL getResource( String name ) {
return parent.getResource(name);
}
@Override
public Enumeration<URL> getResources( String name ) throws IOException {
return parent.getResources(name);
}
@Override
public String toString() {
return parent.toString();
}
@Override
public void setDefaultAssertionStatus(boolean enabled) {
parent.setDefaultAssertionStatus(enabled);
}
@Override
public void setPackageAssertionStatus(String packageName, boolean enabled) {
parent.setPackageAssertionStatus(packageName, enabled);
}
@Override
public void setClassAssertionStatus(String className, boolean enabled) {
parent.setClassAssertionStatus(className, enabled);
}
@Override
public void clearAssertionStatus() {
parent.clearAssertionStatus();
}
}
Usage:
public static ClassLoader cachingClassLoader = new MyClassLoader(FXMLLoader.getDefaultClassLoader());
FXMLLoader loader = new FXMLLoader(resource);
loader.setClassLoader(cachingClassLoader);
This significantly speeds up the performance. However, there is no workaround for step 2, so this might still be a problem.
However, there are already feature requests in the official JavaFX jira for this. It would be nice of you to support this requests.
Links:
FXMLLoader should be able to cache imports and properties between to load() calls:
https://bugs.openjdk.java.net/browse/JDK-8090848
add setAdapterFactory() to the FXMLLoader:
https://bugs.openjdk.java.net/browse/JDK-8102624
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With