Java 绑定不匹配错误：类型不是有效的替代品
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Bound Mismatch Error: The type is not a valid substitute
提问by user3094713
Bound Mismatch Error: The Type is not a valid substitute
绑定不匹配错误：类型不是有效的替代品
Task: I want to store "Song class object" in ImmutableSet through PlayList class.
任务：我想通过 PlayList 类将“歌曲类对象”存储在 ImmutableSet 中。
I have three classes.
我有三个班级。
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
采纳答案by Kevin Bowersox
If you are adding a Songto ImmutableBinaryTreesong must satisfy the bounds of the type parameter on ImmutableBinaryTree, meaning it must implement the Comparableinterface since the type parameter specifies the bounds T extends Comparable<T>.
如果您要添加Song到ImmutableBinaryTree歌曲必须满足的类型参数的范围ImmutableBinaryTree，这意味着它必须实现Comparable，因为类型参数指定的范围接口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;
}
}
