用通用Java实现接口

Question

我无法在element和上调用字符串方法argument。UML图告诉我StartsWith该类具有泛型类型T>String。我在另一篇文章中读到，您需要以这种方式实现它<T extends String>。我想在这里的方法中用Object代替T，public boolean predicate(Object element, Object argument)但是编译器向我抛出那是不可能的。

界面：

public interface Intaf<T> {

    public boolean pres(T element, T argument);

}

班级：

public class StartsWith <T extends String> implements Intaf {

    @Override

    public boolean pres(Object element, Object argument) {

        String firstLetterElement = element.substring(0,1);

        String firstLetterArgument = argument.substring(0,1);

        return firstLetterElement.equals(firstLetterArgument);

    }

}

Answer 1

改成public class StartsWith <T extends String> implements Intaf<T> {&nbsp; &nbsp; @Override&nbsp; &nbsp; public boolean pres(T element, T argument) {&nbsp; &nbsp; &nbsp; &nbsp; String firstLetterElement = element.substring(0,1);&nbsp; &nbsp; &nbsp; &nbsp; String firstLetterArgument = argument.substring(0,1);&nbsp; &nbsp; &nbsp; &nbsp; return firstLetterElement.equals(firstLetterArgument);&nbsp; &nbsp; }}

Answer 2

您要实现Intaf<T>。只是说Intaf暗示Intaf<Object>。

Answer 3

您需要将asIntaf<T>更改并将参数更改为T类型@Overridepublic boolean pres(T element, T argument) {&nbsp;....}