How to @Override an Attribute declared in an Interface implemented in a class

Question

Interface:

package II_1_b;



public interface Bezeichnung {

public String Bezeichnungi = "Hallo";
public abstract void setBezeichnung();
}

class:

package II_1_b;

public class Speerwurf extends SportDaten implements Bezeichnung {

private double weite;

 @Override
   public void setBezeichnung(){    //Here we want to Override the String in 
     Bezeichnungi = "Test";         //the Interface
}



public Speerwurf(String n, double w, String bez) {
    super(n);
    this.weite = w;
    bez = Bezeichnungi;
}

@Override
public void display() {
    System.out.println("Speerwurf von " + this.SportlerName + ":\n"
            + weite + " Meter " + Bezeichnungi);
 }

}

You can see our Code here, I commented the problem area and hope you can help us. Stackoverflow tells me to add more details, so I'm gonna describe what I'm going to have for lunch: I think I will make myself a TK-Pizza, maybe 2. I'm often very hungry.

Answer 1

从接口继承到类的字符串 Bezeichnungi 是最终的，因此不能被覆盖。

Answer 2

As @slaw stated, fields in interfaces cannot be changed and are thus static and final. Additionally, there is no sense of declaring fields in an interface, because it only declares a certain behaviour and not a state. To make things work like you showed here, you need to use an abstract class:

package II_1_b;



public abstract class Bezeichnung {

public protected String Bezeichnungi = "Hallo";
public abstract void setBezeichnung();
} 

Concrete class:

package II_1_b;

public class Speerwurf extends Bezeichnung { //think about how to handle SportDaten!

private double weite;

 @Override
   public void setBezeichnung(){    //Here we want to Override the String in 
     Bezeichnungi = "Test";         //the Interface
}



public Speerwurf(String n, double w, String bez) {
    super(n);
    this.weite = w;
    bez = Bezeichnungi;
}

@Override
public void display() {
    System.out.println("Speerwurf von " + this.SportlerName + ":\n"
            + weite + " Meter " + Bezeichnungi);
 }

}

Since we dont know your concrete use case, we cannot help you except of telling you why it does not work the way it should