查找最近使用的列表元素Java的索引

Question

我正在构建一个食谱应用程序。我创建了一个食谱数据库，其中的信息是使用ArrayList设置的。我的想法是创建一个"近期食谱"。节中，我之前创建的模板被食谱本身的按钮所取代。问题:如何找到之前使用过的三个菜谱的索引?

我的数据库:'

public class ReceiptsBase {
ArrayList<ArrayList<Integer>> recipesAll = new ArrayList<>();
public ReceiptsBase() {
ArrayList<Integer> mushroom_soup = new ArrayList<>();
mushroom_soup.add (R.drawable.mush);
mushroom_soup.add (R.string.mush_name);
mushroom_soup.add (R.string.mush_info);
mushroom_soup.add (R.string.mush_prep);
mushroom_soup.add(R.drawable.mush_blur);
mushroom_soup.add(R.string.mush_ingr);
ArrayList<Integer> tomato_soup = new ArrayList<>();
tomato_soup.add (R.drawable.tomato);
tomato_soup.add (R.string.tomato_name);
tomato_soup.add (R.string.tomato_info);
tomato_soup.add (R.string.tomato_prep);
tomato_soup.add(R.drawable.tomato_blur);
tomato_soup.add(R.string.tomato_ingr);
ArrayList<Integer> potato_soup = new ArrayList<>();
potato_soup.add (R.drawable.potatosoup);
potato_soup.add (R.string.potsoup_name);
potato_soup.add (R.string.potsoup_info);
potato_soup.add (R.string.potsoup_prep);
potato_soup.add(R.drawable.potatosoup_blur);
potato_soup.add(R.string.potsoup_ingr);
ArrayList<Integer> onion_meal = new ArrayList<>();
onion_meal.add (R.drawable.onion);
onion_meal.add (R.string.onion_name);
onion_meal.add (R.string.onion_info);
onion_meal.add (R.string.onion_prep);
onion_meal.add(R.drawable.onion_blur);
onion_meal.add(R.string.onion_ingr);
ArrayList<Integer> pancakes = new ArrayList<>();
pancakes.add (R.drawable.pancakes);
pancakes.add (R.string.pank_name);
pancakes.add (R.string.pank_info);
pancakes.add (R.string.pank_prep);
pancakes.add(R.drawable.pancakes_blur);
pancakes.add(R.string.pank_ingr);
ArrayList<Integer> dumplings = new ArrayList<>();
dumplings.add (R.drawable.dumpl);
dumplings.add (R.string.dumpl_name);
dumplings.add (R.string.dumpl_info);
dumplings.add (R.string.dumpl_prep);
dumplings.add(R.drawable.dumpl_blur);
dumplings.add(R.string.dumpl_ingr);
ArrayList<Integer> croquettes = new ArrayList<>();
croquettes.add (R.drawable.croquettes);
croquettes.add (R.string.croq_name);
croquettes.add (R.string.croq_info);
croquettes.add (R.string.croq_prep);
croquettes.add(R.drawable.croquettes_blur);
croquettes.add(R.string.croq_ingr);
ArrayList<Integer> katsudon = new ArrayList<>();
katsudon.add (R.drawable.katsudon);
katsudon.add (R.string.kats_name);
katsudon.add (R.string.kats_info);
katsudon.add (R.string.kats_prep);
katsudon.add(R.drawable.katsudon_blur);
katsudon.add(R.string.kats_ingr);
ArrayList<Integer> garlic_bread = new ArrayList<>();
garlic_bread.add (R.drawable.garlic);
garlic_bread.add (R.string.garl_name);
garlic_bread.add (R.string.garl_info);
garlic_bread.add (R.string.garl_prop);
garlic_bread.add(R.drawable.garlic_blur);
garlic_bread.add(R.string.garlic_ingr);
ArrayList<Integer> potato_pancakes = new ArrayList<>();
potato_pancakes.add (R.drawable.pot_pank);
potato_pancakes.add (R.string.potpank_name);
potato_pancakes.add (R.string.potpank_info);
potato_pancakes.add (R.string.potpank_prep);
potato_pancakes.add(R.drawable.pot_pank_blur);
potato_pancakes.add(R.string.potpank_ingr);
recipesAll.add(mushroom_soup);
recipesAll.add(tomato_soup);
recipesAll.add(potato_soup);
recipesAll.add(onion_meal);
recipesAll.add(pancakes);
recipesAll.add(dumplings);
recipesAll.add(croquettes);
recipesAll.add(katsudon);
recipesAll.add(garlic_bread);
recipesAll.add(potato_pancakes);
}
public ArrayList<Integer> getReceipt(int receiptIndex) {
return recipesAll.get(receiptIndex);
}
public ArrayList<ArrayList<Integer>> getReceipts() {
return recipesAll;
}

一节我的代码:

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
hideSystemUI();
Button button_recipes = findViewById(R.id.button2);
button_recipes.setOnClickListener(view -> openRecipes());
Button button_search = findViewById(R.id.button3);
button_search.setOnClickListener(view -> openSearch());
Button button_supriseme = findViewById(R.id.button4);
button_supriseme.setOnClickListener(view -> openSupriseMe());
ImageButton recent1 = findViewById(R.id.rec1);
ImageButton recent2 = findViewById(R.id.rec2);
ImageButton recent3 = findViewById(R.id.rec3);
//        recent1.setImageDrawable(getDrawable());
//        recent2.setImageDrawable(getDrawable());
//        recent3.setImageDrawable(getDrawable());
//
//        recent1.setOnClickListener(view -> openRecipe());
//        recent2.setOnClickListener(view -> openRecipe());
//        recent3.setOnClickListener(view -> openRecipe());
}
public void openRecipes(){
Intent rec = new Intent(this, recipes.class);
startActivity(rec);
finish();
}
public void openSearch(){
Intent sea = new Intent(this, search.class);
startActivity(sea);
finish();
}
public void openSupriseMe(){
Intent sup = new Intent(this, Example.class);
startActivity(sup);
finish();
}
public void openRecipe(int recipeIndex){
Intent sup = new Intent(this, Example.class);
sup.putExtra("recipeIndex", recipeIndex);
startActivity(sup);
finish();
}

<代码>

Answer 1

创建一个长度为3的新数组，并在使用时在其中添加一个食谱。当数组已满并且使用菜谱时，设置:

Recipe temp0 = array[0]
array[0] = most recently used
Recipe temp1 = array[1]
array[1] = temp0;
array[2] = temp1;

，当然，也可以用另一种方法，其中array[0]是最近使用的。那就是:

PP_5我不知道你的食谱是什么类型的对象，所以我就叫它们type Recipe。