Android:无法强制转换为java.lang.CharSequence
我不知道我在这方面哪里出了问题,我正在尝试在一个回收视图中列出一个食谱的成分,我只是无法让onBindViewHolder工作,不管我尝试了什么。下面是适配器代码以及xml Recipe.class。本质上,我需要向recyclerView显示Recipe类的结果 配方类Android:无法强制转换为java.lang.CharSequence,android,sqlite,android-recyclerview,Android,Sqlite,Android Recyclerview,我不知道我在这方面哪里出了问题,我正在尝试在一个回收视图中列出一个食谱的成分,我只是无法让onBindViewHolder工作,不管我尝试了什么。下面是适配器代码以及xml Recipe.class。本质上,我需要向recyclerView显示Recipe类的结果 配方类 public class Recipe extends MainActivity { TabLayout tabLayout; ImageView recipeImage; TextView desc
public class Recipe extends MainActivity {
TabLayout tabLayout;
ImageView recipeImage;
TextView descriptionText, courseText, servingsText, costText, caloriesText, methodText;
RecyclerView listIngredient;
SQLiteDatabase db;
String search_name;
Cursor c;
RecyclerViewAdapter adapterRecipe;
List<RecipeList> itemRecipe = new ArrayList<>();
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recipe);
//search_name = getIntent().getStringExtra("NAME");
search_name = "Speedy chicken couscous";
loadRecipe();
//recyclerview Recipe
adapterRecipe = new RecyclerViewAdapter(this, itemRecipe);
listIngredient = findViewById(R.id.listIngredient);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(this,
LinearLayoutManager.VERTICAL, false);
listIngredient.setLayoutManager(mLayoutManager);
listIngredient.setItemAnimator(new DefaultItemAnimator());
listIngredient.setAdapter(adapterRecipe);
}
public void loadRecipe() {
itemRecipe.clear();
db = (new DatabaseManager(this).getWritableDatabase());
String RECIPE_SEARCH = " SELECT A.recipe, A.ingredient_quantity, B.measurement_name, B.ingredient_name, B.description " +
"FROM " + DatabaseManager.TABLE_QUANTITY + " AS A JOIN " + DatabaseManager.TABLE_INGREDIENTS +
" AS B ON A.ingredient = B.ingredient_name";
String selectQuery = "";
selectQuery = RECIPE_SEARCH + " WHERE A.recipe LIKE ?";
c = db.rawQuery(selectQuery, new String[]{"%" + search_name + "%"});
if (c.moveToFirst()) {
do {
RecipeList recipeList = new RecipeList();
recipeList.setRecipe(c.getString(c.getColumnIndex("recipe")));
recipeList.setIngredient_amount(c.getString(c.getColumnIndex("ingredient_quantity")));
recipeList.setMeasurement_name(c.getString(c.getColumnIndex("measurement_name")));
recipeList.setIngredient_name(c.getString(c.getColumnIndex("ingredient_name")));
recipeList.setDescription(c.getString(c.getColumnIndex("description")));
itemRecipe.add(recipeList);
} while (c.moveToNext());
c.close();
}
}
}
互惠列表模型
公共类接受者{
private Integer id;
private Double ingredient_quantity;
private String recipe;
private String measurement_name;
private String ingredient_name;
private String description;
private String ingredient_amount = String.valueOf(ingredient_quantity);
public RecipeList(){
}
public RecipeList(String recipe, String ingredient_amount, String measurement_name, String ingredient_name, String description) {
this.recipe = recipe;
this.ingredient_amount = ingredient_amount;
this.measurement_name = measurement_name;
this.ingredient_name = ingredient_name;
this.description = description;
}
public String getRecipe() {
return recipe;
}
public void setRecipe(String recipe) {
this.recipe = recipe;
}
public String getIngredient_amount() {
return ingredient_amount;
}
public void setIngredient_amount(String ingredient_amount) {
this.ingredient_amount = ingredient_amount;
}
public String getMeasurement_name() {
return measurement_name;
}
public void setMeasurement_name(String measurement_name) {
this.measurement_name = measurement_name;
}
public String getIngredient_name() {
return ingredient_name;
}
public void setIngredient_name(String ingredient_name) {
this.ingredient_name = ingredient_name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
更新错误
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
private List<RecipeList> itemRecipe;
private LayoutInflater mInflater;
private ItemClickListener mClickListener;
// data is passed into the constructor
RecyclerViewAdapter(Context context, List<RecipeList> data) {
this.mInflater = LayoutInflater.from(context);
this.itemRecipe = data;
}
// inflates the row layout from xml when needed
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.fragment_item, parent, false);
return new ViewHolder(view);
}
// binds the data to the TextView in each row
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.myTextView.setText(itemRecipe.get(position));
}
// total number of rows
@Override
public int getItemCount() {
return itemRecipe.size();
}
// stores and recycles views as they are scrolled off screen
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView myTextView;
ViewHolder(View itemView) {
super(itemView);
myTextView = itemView.findViewById(R.id.listIngredient);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (mClickListener != null) mClickListener.onItemClick(view, getAdapterPosition());
}
}
// allows clicks events to be caught
void setClickListener(ItemClickListener itemClickListener) {
this.mClickListener = itemClickListener;
}
// parent activity will implement this method to respond to click events
public interface ItemClickListener {
void onItemClick(View view, int position);
}
尝试在空对象引用上调用虚拟方法“void android.widget.TextView.setText(java.lang.CharSequence)”
在这一行:
holder.myTextView.setText(itemRecipe.get(position).toString());在代码
itemRecipe.get(position)
中返回RecipeList
此对象您将RecipeList直接传递给setText,setText需要字符串,请尝试在此处传递字符串值holder.myTextView.setText(//传递字符串)
将RecipeList作为字符串重写传递给RecipeList中的字符串
示例:这里添加了示例格式,并包含了toString中的所有变量
@Override
public String toString() {
return "RecipeList{" +
"id=" + id +
", ingredient_quantity=" + ingredient_quantity +
", recipe='" + recipe + '\'' +
", measurement_name='" + measurement_name + '\'' +
", ingredient_name='" + ingredient_name + '\'' +
", description='" + description + '\'' +
", ingredient_amount='" + ingredient_amount + '\'' +
'}';
}
调用setText中RecipeList对象上的toString
例:
发布带有问题的错误日志。花点时间阅读以下内容:谢谢,我如何将字符串值放在这里?我已经实现了您的建议,我得到了“无法解析符号'toString'”。我在RecipeList模型中使用了toString方法。我在RecipeList中使用了toString方法。类此解决方案解决了我遇到的问题,现在我面临的问题是,它什么都不做,只是停止运行。
private Integer id;
private Double ingredient_quantity;
private String recipe;
private String measurement_name;
private String ingredient_name;
private String description;
private String ingredient_amount = String.valueOf(ingredient_quantity);
public RecipeList(){
}
public RecipeList(String recipe, String ingredient_amount, String measurement_name, String ingredient_name, String description) {
this.recipe = recipe;
this.ingredient_amount = ingredient_amount;
this.measurement_name = measurement_name;
this.ingredient_name = ingredient_name;
this.description = description;
}
public String getRecipe() {
return recipe;
}
public void setRecipe(String recipe) {
this.recipe = recipe;
}
public String getIngredient_amount() {
return ingredient_amount;
}
public void setIngredient_amount(String ingredient_amount) {
this.ingredient_amount = ingredient_amount;
}
public String getMeasurement_name() {
return measurement_name;
}
public void setMeasurement_name(String measurement_name) {
this.measurement_name = measurement_name;
}
public String getIngredient_name() {
return ingredient_name;
}
public void setIngredient_name(String ingredient_name) {
this.ingredient_name = ingredient_name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
@Override
public String toString() {
return "RecipeList{" +
"id=" + id +
", ingredient_quantity=" + ingredient_quantity +
", recipe='" + recipe + '\'' +
", measurement_name='" + measurement_name + '\'' +
", ingredient_name='" + ingredient_name + '\'' +
", description='" + description + '\'' +
", ingredient_amount='" + ingredient_amount + '\'' +
'}';
}
holder.myTextView.setText(itemRecipe.get(position).toString)