Question

绑定不匹配错误：类型不是有效的替代

任务：我想通过PlayList类在“ImmutableSet”中存储“Song类对象”。

我有三节课。

public class ImmutableBinaryTree< T extends Comparable<T>> implements ImmutableSet<T> { }

public class Song { }


public class PlayList<T extends Comparable<T>> {
     private Song songs;  
     ImmutableSet<Song> immutableSet; // Bound Mismatch error occurring here

Answer 1

如果要添加Song到ImmutableBinaryTree首歌必须满足ImmutableBinaryTree上类型参数的范围，这意味着它必须实现Comparable接口，因为类型参数指定边界T extends Comparable<T>。

public class Song implements Comparable<Song>{

    @Override
    public int compareTo(Song arg0) {
        //provide implementation here
        //See effective java for appropriate implementation conditions
        return 0;
    }

}

绑定不匹配错误：类型不是有效替代

1 个答案: