每次 Activity 根据自定义对象中的 bool 值启动时，我都试图更改回收站 View 中按钮的图标。我认为这必须在适配器内完成，因为并非每个组按钮都具有相同的背景。
下面是我的回收器 View 适配器的代码:
public class RecipeListAdapter extends RecyclerView.Adapter<RecipeListAdapter.ViewHolder>{
private List<Recipe> mRecipeSet;
private Button mAddToGroceriesButton;
public RecipeListAdapter(List<Recipe> recipes){
mRecipeSet = recipes;
}
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
//This is what will handle what happens when you click a recipe in the recycler view
private TextView mRecipeName;
private TextView mPrepTime;
private TextView mCookTime;
private TextView mServingSize;
private RelativeLayout mRecipeTextSection;
public ViewHolder(View v) {
super(v);
mRecipeName = (TextView) v.findViewById(R.id.recipe_list_recycler_view_recipe_name);
mServingSize = (TextView) v.findViewById(R.id.recipe_list_recycler_view_serving_size);
mPrepTime = (TextView) v.findViewById(R.id.recipe_list_recycler_view_prep_time);
mCookTime = (TextView) v.findViewById(R.id.recipe_list_recycler_view_cook_time);
mRecipeTextSection = (RelativeLayout) v.findViewById(R.id.recycled_item_section_view);
mRecipeTextSection.setOnClickListener(this);
mAddToGroceriesButton = (Button) v.findViewById(R.id.add_to_grocery_list);
mAddToGroceriesButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = getAdapterPosition();
Recipe recipeToGrocery = mRecipeSet.get(position);
//RecipeDB dbHelper = new RecipeDB(v.getContext());
//dbHelper.addGroceryItem(recipeToGrocery);
if(!recipeToGrocery.isInList()) {
RecipeDB dbHelper = new RecipeDB(v.getContext());
dbHelper.addGroceryItem(recipeToGrocery);
recipeToGrocery.setInList(true);
dbHelper.updateRecipe(recipeToGrocery);
mAddToGroceriesButton.setBackgroundResource(R.mipmap.ic_playlist_add_check_black_24dp);
Toast.makeText(v.getContext(), recipeToGrocery.getRecipeName() + " added to grocery list.", Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(v.getContext(), "That recipe is already in the list.", Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public void onClick(View v){
int position = getAdapterPosition();
Intent i = new Intent(v.getContext(), RecipeTextView.class);
Recipe selectedRecipe = mRecipeSet.get(position);
i.putExtra("view_recipe_key", selectedRecipe);
v.getContext().startActivity(i);
}
}
public void add(int position, Recipe item) {
mRecipeSet.add(position, item);
notifyItemInserted(position);
}
public void remove(Recipe item) {
int position = mRecipeSet.indexOf(item);
mRecipeSet.remove(position);
notifyItemRemoved(position);
}
public RecipeListAdapter(ArrayList<Recipe> myRecipeset) {
mRecipeSet = myRecipeset;
}
// Create new views (invoked by the layout manager)
@Override
public RecipeListAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// create a new view
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recipe_item_recycled, parent, false);
ViewHolder vh = new ViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Recipe recipe = mRecipeSet.get(position);
String recipeName = recipe.getRecipeName();
String prepTime = "Prep Time: " + String.valueOf(recipe.getPrepTime()) + " minutes";
String cookTime = "Cook Time: " + String.valueOf(recipe.getCookTime()) + " minutes";
String servingSize = "Servings: " + String.valueOf(recipe.getServings());
holder.mRecipeName.setText(recipeName);
//Only display values if they are not null
if(recipe.getServings() != null) {
holder.mServingSize.setText(servingSize);
}
if (recipe.getPrepTime() != null) {
holder.mPrepTime.setText(prepTime);
}
if(recipe.getCookTime() != null) {
holder.mCookTime.setText(cookTime);
}
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
if(mRecipeSet != null) {
return mRecipeSet.size();
}
return 0;
}
}
我知道如何在单击按钮时更改按钮的背景
mAddToGroceriesButton.setBackgroundResource(R.mipmap.ic_playlist_add_check_black_24dp);
但它显然不会在 Activity 重新启动时保存该按钮的状态。我只是不确定如何在 Activity 启动时检查每个组的 bool 值并相应地更改按钮背景。
我试过用
if(recipe.isInList()){
mAddToGroceriesButton.setBackgroundResource(R.mipmap.ic_playlist_add_check_black_24dp);
}
在 onBindViewHolder 方法中，但它什么也没做，而且我很确定无论如何这都不是正确的位置。我知道 bool 值工作正常，因为我在其他地方使用它并且工作正常。
这是相关的 XML 代码:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/apk/res/android"
android:layout_margin="7dp"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:id="@+id/recycled_item_section_view"
android:elevation="30dp"
android:background="@drawable/background_border"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
tools:text="Recipe name"
android:textSize="24dp"
android:textColor="@color/black"
android:id="@+id/recipe_list_recycler_view_recipe_name"
android:paddingBottom="3dp"
android:maxWidth="275dip"
android:singleLine="false"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="18dp"
android:textColor="@color/black"
android:layout_below="@id/recipe_list_recycler_view_recipe_name"
android:id="@+id/recipe_list_recycler_view_serving_size"
android:paddingBottom="3dp"/>
<Button
android:layout_width="35dp"
android:layout_height="35dp"
android:background="@mipmap/ic_playlist_add_black_24dp"
android:height="36dp"
android:padding="8dp"
android:layout_alignParentRight="true"
android:id="@+id/add_to_grocery_list"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/recipe_list_recycler_view_serving_size"
android:layout_alignParentLeft="true"
android:textSize="18dp"
android:textColor="@color/black"
android:id="@+id/recipe_list_recycler_view_prep_time"
android:paddingBottom="3dp"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/recipe_list_recycler_view_prep_time"
android:textSize="18dp"
android:textColor="@color/black"
android:layout_alignParentLeft="true"
android:id="@+id/recipe_list_recycler_view_cook_time"/>
</RelativeLayout>
配方类:
public class Recipe implements Parcelable {
//These are all of the qualities a recipe contains, we will create an arraylist of this in the activity
private String mRecipeName;
private int mID;
private String mServings;
private String mPrepTime;
private String mCookTime;
private boolean isInList;
private List<String> mIngredients;
private List<String> mDirections;
public Recipe(){
}
public Recipe(int id, String name, String serving, String prep, String cook, List<String>
ingredientsList, List<String> directionsList, boolean inList){
this.mID = id;
this.mRecipeName = name;
this.mServings = serving;
this.mPrepTime = prep;
this.mCookTime = cook;
this.mIngredients = ingredientsList;
this.mDirections = directionsList;
this.isInList = inList;
}
public Recipe(String name, String serving, String prep, String cook, List<String>
ingredientsList, List<String> directionsList, boolean inList){
this.mRecipeName = name;
this.mServings = serving;
this.mPrepTime = prep;
this.mCookTime = cook;
this.mIngredients = ingredientsList;
this.mDirections = directionsList;
this.isInList = inList;
}
public String getRecipeName() {
return mRecipeName;
}
public int getID() {
return mID;
}
public void setID(int id){
mID = id;
}
public String getServings() {
return mServings;
}
public String getPrepTime() {
return mPrepTime;
}
public void setRecipeName(String recipeName) {
mRecipeName = recipeName;
}
public void setServingSize(String servings) {
mServings = servings;
}
public void setPrepTime(String prepTime) {
mPrepTime = prepTime;
}
public void setServings(String servings) {
mServings = servings;
}
public List<String> getIngredients() {
return mIngredients;
}
public List<String> getDirections() {
return mDirections;
}
public String getCookTime() {
return mCookTime;
}
public void setCookTime(String cookTime) {
mCookTime = cookTime;
}
public void setIngredients(List<String> ingredients) {
mIngredients = ingredients;
}
public void setDirections(List<String> directions) {
mDirections = directions;
}
public boolean isInList() {
return isInList;
}
public void setInList(boolean inList) {
isInList = inList;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(this.mRecipeName);
dest.writeInt(this.mID);
dest.writeString(this.mServings);
dest.writeString(this.mPrepTime);
dest.writeString(this.mCookTime);
dest.writeByte(this.isInList ? (byte) 1 : (byte) 0);
dest.writeStringList(this.mIngredients);
dest.writeStringList(this.mDirections);
}
protected Recipe(Parcel in) {
this.mRecipeName = in.readString();
this.mID = in.readInt();
this.mServings = in.readString();
this.mPrepTime = in.readString();
this.mCookTime = in.readString();
this.isInList = in.readByte() != 0;
this.mIngredients = in.createStringArrayList();
this.mDirections = in.createStringArrayList();
}
public static final Creator<Recipe> CREATOR = new Creator<Recipe>() {
@Override
public Recipe createFromParcel(Parcel source) {
return new Recipe(source);
}
@Override
public Recipe[] newArray(int size) {
return new Recipe[size];
}
};
}
以及使用适配器的主要 Activity 类:
public class RecipeList extends AppCompatActivity{
private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private int REQUEST_CODE=1;
private Button mNavigateGroceryButton;
RecipeDB dbHelper = new RecipeDB(this);
List<Recipe> recipes;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
recipes = dbHelper.getAllRecipes();
setContentView(R.layout.activity_recipe_list);
mRecyclerView = (RecyclerView) findViewById(R.id.list_recycler_view);
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new RecipeListAdapter(recipes);
mRecyclerView.setAdapter(mAdapter);
mNavigateGroceryButton = (Button) findViewById(R.id.navigate_to_groceries_button_list_view);
mNavigateGroceryButton.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Intent i = new Intent(RecipeList.this, ExpandableListViewActivity.class);
//Log.d("Navigate", "navigate pressed" );
startActivity(i);
}
});
}
@Override
public void onBackPressed() {
}
public boolean onOptionsItemSelected(MenuItem item){
//Handles menu buttons
switch (item.getItemId()){
case R.id.recipe_list_add_recipe_actionbar_button:
//This button creates a new empty Recipe object and passes it to the EditRecipe class
//The Recipe object is passed as a parcelable
Recipe passedRecipe = new Recipe();
Intent i = new Intent(RecipeList.this, EditRecipe.class);
i.putExtra("passed_recipe_key", (Parcelable) passedRecipe);
startActivityForResult(i, REQUEST_CODE);
return true;
default:
Log.d("Name,", "default called");
return super.onOptionsItemSelected(item);
}
}
public void addNewReRecipe(Recipe recipe){
dbHelper.addRecipe(recipe);
recipes = dbHelper.getAllRecipes();
mAdapter = new RecipeListAdapter(recipes);
mRecyclerView.setAdapter(mAdapter);
}
//Makes the menu bar appear as it is in the action_bar_recipe_list_buttons menu layout file
@Override
public boolean onCreateOptionsMenu(Menu menu){
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.action_bar_recipe_list_buttons, menu);
return true;
}
//This code is called after creating a new recipe. This is only for creating, and not editing.
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_CODE){
if(resultCode == Activity.RESULT_OK) {
Recipe createdRecipe = data.getExtras().getParcelable("recipe_key");
addNewReRecipe(createdRecipe);
}
}
}
}
最佳答案
看起来您需要在 ViewHolder 的顶部与其他 View 一起声明您的按钮。因此，将声明从适配器的顶部移开:
私有(private)按钮 mAddToGroceriesButton;
然后在您的 onBindViewHolder 方法中，您可以通过 holder 获取对按钮的引用并设置背景:
if(recipe.isInList()) {
holder.mAddToGroceriesButton.setBackgroundResource(R.mipmap.ic_playlist_add_check_black_24dp);
}
关于android - 基于 bool 值更改适配器类中回收器 View 中按钮的图标，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42336265/