java - 将泛型类型参数与 Java 中的接口(interface)相结合

Question

与许多继承问题一样，我发现很难解释我想做什么。但是一个快速(但奇特)的例子应该可以解决问题:

public interface Shell{


    public double getSize();

}

public class TortoiseShell implements Shell{
     ...
     public double getSize(){...} //implementing interface method
     ...
     public Tortoise getTortoise(){...} //new method
     ...
}

public class ShellViewer<S extends Shell>{

     S shell;

     public ShellViewer(S shell){
         this.shell = shell;
         ...
     }

}

public class TortoiseShellViewer<T extends TortoiseShell> extends ShellViewer{

    public TortoiseShellViewer(T tShell){
         super(tShell); //no problems here...
    }

    private void removeTortoise(){
        Tortoise t = tShell.getTortoise(); //ERROR: compiler can not find method in "Shell"
        ...
    }
}

编译器无法识别我想为 getTortoise() 使用特定的 Shell 实现。我哪里出错了？

Answer 1

根据您在此处提供的内容，问题在于:

public class TortoiseShellViewer<T extends TortoiseShell> extends ShellViewer

没有正确指定 ShellViewer(通用)。应该是:

public class TortoiseShellViewer<T extends TortoiseShell> extends ShellViewer<T>