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（但特殊）的例子应该可以解决这个问题：

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Shell的特定实现。我哪里出错？

Answer 1

根据您在此处提供的内容，问题是：

public class TortoiseShellViewer<T extends TortoiseShell> extends ShellViewer

未正确指定ShellViewer（通用）。它应该是：

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

Answer 2

你想要这个：

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

Answer 3

removeTortoise中的tShell是什么？它是基类ShellViewer中的Shell类型的实例吗？

将泛型类型参数与Java中的接口相结合

3 个答案: