实现一个 ObservableValue

Question

我有这个对象：

public class Oggetto{
    private int value;
    private boolean valid;

    public Oggetto(int value, boolean valid) {
        this.value = value;
        this.valid = valid;
    }

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }

    public boolean isValid() {
        return valid;
    }

    public void setValid(boolean valid) {
        this.valid = valid;
    }    
}

我想实现一个 Observable 对象，当内部发生变化时触发事件 这里是可观察对象：

public class OggettoOsservabile implements ObservableValue<Oggetto>{

    private Oggetto value;

    OggettoOsservabile(int i, boolean b) {
        this.value=new Oggetto(i, b);
    }
    @Override
    public void addListener(ChangeListener<? super Oggetto> listener) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
    @Override
    public void removeListener(ChangeListener<? super Oggetto> listener) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
    @Override
    public Oggetto getValue() {
        return value;
    }
    @Override
    public void addListener(InvalidationListener listener) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
    @Override
    public void removeListener(InvalidationListener listener) {
        throw new UnsupportedOperationException("Not supported yet."); 
    }  
}

我不知道如何继续以检测“Oggetto”类的变化并向注册监听器发送通知。

OggettoOsservabile oggetto = new OggettoOsservabile(1, false);              
oggetto.addListener(new ChangeListener<Oggetto>() {
     public void changed(ObservableValue<? extends Oggetto> observable, Oggetto oldValue, Oggetto newValue) {
           System.out.println("changed " + oldValue + "->" + newValue);   
     }
});

Answer 1

使用标准 JavaFX 属性实现您的 Oggetto 类：

import javafx.beans.property.BooleanProperty ;
import javafx.beans.property.IntegerProperty ;
import javafx.beans.property.SimpleBooleanProperty ;
import javafx.beans.property.SimpleIntegerProperty ;

public class Oggetto {

    private final IntegerProperty value = new SimpleIntegerProperty() ;

    public final IntegerProperty valueProperty() {
        return value ;
    }

    public final int getValue() {
        return value.get();
    }

    public final void setValue(int value) {
        this.value.set(value);
    }

    private final BooleanProperty valid = new SimpleBooleanProperty();

    public final BooleanProperty validProperty() {
        return valid ;
    }

    public final boolean isValid() {
        return valid.get();
    }

    public final void setValid(boolean valid) {
        this.valid.set(valid);
    }

    public Oggetto(int value, boolean valid) {
        setValue(value);
        setValid(valid);
    }
}

这可能就是您所需要的，因为您只需观察各个属性即可。但是如果你想要一个在任一属性发生变化时通知失效监听器的类，你可以扩展ObjectBinding：

import javafx.beans.binding.ObjectBinding ;

public class OggettoObservable extends ObjectBinding {

    private final Oggetto value ;

    public OggettoObservable(int value, boolean valid) {
        this.value = new Oggetto(value, valid);
        bind(this.value.valueProperty(), this.value.validProperty());
    }

    @Override
    public Oggetto computeValue() {
        return value ;
    }
}

Answer 2

import javafx.beans.InvalidationListener;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;

    public class VerySimply implements ObservableValue<Integer> {
    private int newValue;
    public ChangeListener<Integer> listener = new ChangeListener<Integer>() {
        @Override
        public void changed(ObservableValue<? extends Integer> observable, Integer oldValue, Integer newValue) {
            System.out.println(" :) "+ newValue.intValue());
        }
    };

    @Override
    public void addListener(ChangeListener<? super Integer> listener) {

    }

    @Override
    public void removeListener(ChangeListener<? super Integer> listener) {

    }

    @Override
    public Integer getValue() {
        return newValue;
    }

    @Override
    public void addListener(InvalidationListener listener) {

    }

    @Override
    public void removeListener(InvalidationListener listener) {

    }

    public void setNewValue(int newValue) {
        int oldValue = this.newValue;
        this.newValue = newValue;
        listener.changed(this,oldValue,this.newValue);

    }
}