Question

我将Java类转换为kotlin，并得到了以下错误：超类型的直接参数不允许进行投影

Java类是

public class RecipeViewHolder extends ParentViewHolder {

    private static final float INITIAL_POSITION = 0.0f;
    private static final float ROTATED_POSITION = 180f;

    @NonNull
    private final ImageView mArrowExpandImageView;
    private TextView mRecipeTextView;
    private TextView position;
    private TextView total;

    public RecipeViewHolder(@NonNull View itemView) {
        super(itemView);
        mRecipeTextView = (TextView) itemView.findViewById(R.id.recipe_textview);
        position = (TextView) itemView.findViewById(R.id.textViewPosition);
        total = (TextView) itemView.findViewById(R.id.textViewTotal);

        mArrowExpandImageView = (ImageView) itemView.findViewById(R.id.arrow_expand_imageview);
    }

    public void bind(@NonNull Recipe recipe) {
        mRecipeTextView.setText(recipe.getName());

        try {

            position.setText("Position: " + recipe.getJson().getString("position"));
            total.setText("Total Bid Amount: " + recipe.getJson().getString("type"));

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

}

转换后的Kotlin类为

//Error occurs here in Parentvireholder<*,*>

class RecipeViewHolder(itemView: View) : ParentViewHolder<*, *>(itemView) {

    private val mArrowExpandImageView: ImageView
    private val mRecipeTextView: TextView
    private val position: TextView
    private val total: TextView

    init {

        mRecipeTextView = itemView.findViewById<View>(R.id.recipe_textview) as TextView
        position = itemView.findViewById<View>(R.id.textViewPosition) as TextView
        total = itemView.findViewById<View>(R.id.textViewTotal) as TextView

        mArrowExpandImageView = itemView.findViewById<View>(R.id.arrow_expand_imageview) as ImageView

    }

    fun bind(recipe: Recipe) {

        mRecipeTextView.text = recipe.name

        try {

            position.text = "Position: " + recipe.json!!.getString("position")
            total.text = "Total Bid Amount: " + recipe.json!!.getString("type")

        } catch (e: JSONException) {
            e.printStackTrace()
        }

    }

}

显示的评论中出现错误。我尝试了Any修复程序，但显示Type参数不在其范围内

Answer 1

Kotlin要求您指定超类的通用参数。

您需要用显式类型替换超类泛型类型中的*或为子类指定泛型类型。

如果超类泛型类型仅限于特定类型，则不能使用Any。看一下ParentViewHolder的类定义，并声明与之相同的类型：

RecipeViewHolder<P extends Parent<C>, C>(itemView: View) : ParentViewHolder<P, C>

或

RecipeViewHolder(itemView: View) : ParentViewHolder<MyParent, MyChild>

超型Kotlin的直接参数不允许投影

1 个答案: