Question

我想做的就是将一个浮动绑定到另一个：

import javafx.beans.property.FloatProperty;
import javafx.beans.property.SimpleFloatProperty;

public class BindingTest
{
   public static void main(String[] args) 
   {      
     float bound=0;
     float binder= -1;

     FloatProperty boundP= new SimpleFloatProperty(bound);
     FloatProperty binderP=new SimpleFloatProperty(binder);
     binderP.bind(boundP);
     System.out.println("Before: \n\tbinder: " +binder + "\n\tbound: " + bound);
     binder= 23; 
     System.out.println("After: \n\tbinder: " +binder + "\n\tbound: " + bound);

    }
}

如果您懒得运行它，当变量bound更改为值23时，变量binder将不会更新。我究竟做错了什么？谢谢！

Answer 1

所以我认为你对属性如何运作有错误的想法。我为更好的理解做了一个例子：

import javafx.beans.binding.Bindings;
import javafx.beans.binding.NumberBinding;
import javafx.beans.property.FloatProperty;
import javafx.beans.property.SimpleFloatProperty;

public class Test {

  public static void main(String... args) {
    FloatProperty dummyProp = new SimpleFloatProperty(0);
    FloatProperty binderP = new SimpleFloatProperty(-1);
    //Means boundP = dummyProp + binderP
    NumberBinding boundP = Bindings.add(binderP, dummyProp);
    System.out.format("%f + %f = %f%n", dummyProp.floatValue(), binderP.floatValue(), boundP.floatValue());
    dummyProp.set(2);
    System.out.format("%f + %f = %f%n", dummyProp.floatValue(), binderP.floatValue(), boundP.floatValue());

    // dummyProp is equal to binderP but dummyProp is a read-only value
    dummyProp.bind(binderP);
    System.out.format("%f, %f%n", dummyProp.floatValue(), binderP.floatValue());
    // throws an exception because dummyProp is bound to binderP
    // dummyProp.set(5);
    binderP.set(5f);
    System.out.format("%f, %f%n", dummyProp.floatValue(), binderP.floatValue());

    dummyProp.unbind();

    // dummyProp == binderP always
    dummyProp.bindBidirectional(binderP);
    System.out.format("%f, %f%n", dummyProp.floatValue(), binderP.floatValue());
    dummyProp.set(3f);
    System.out.format("%f, %f%n", dummyProp.floatValue(), binderP.floatValue());
    binderP.set(10f);
    System.out.format("%f, %f%n", dummyProp.floatValue(), binderP.floatValue());

    // boundP always consists of the sum
    System.out.format("%f%n", boundP.floatValue());
  }

}

java8绑定两个浮点数

1 个答案: