如何使 recyclerview 根据百分比只显示一个数组？

Question

我想要一个 recyclerview 只显示一个数组，但在 arraylist 中有更多。必须显示的那个不能总是相同的，但这将取决于某些百分比。例如：第一个数组有 20% 的机会，第二个 50% 和第三个 50% 也有。并随机显示一个。但是当我刷新屏幕时它会改变。我想我应该做的是为数组列表中的每个数组设置百分比，但我不知道该怎么做以及下一步该做什么。那是我的java文件。public class Comida extends AppCompatActivity implements Adaptador2.OnRecipeListener {    private RecyclerView recyclerView1;    List<Entidad2> listItems;    Adaptador2 adaptor;    private Entidad2 entidad1,entidad2,entidad3;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,                WindowManager.LayoutParams.FLAG_FULLSCREEN);        setContentView(R.layout.activity_comida);        recyclerView1 = findViewById(R.id.lv_1);        LinearLayoutManager layoutManager = new LinearLayoutManager(this);        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);        recyclerView1.setLayoutManager(layoutManager);        listItems = new ArrayList<>();        entidad1 = new Entidad2(R.drawable.calabacines_3, "Solomillo a la plancha", " 10 min.", 4, 20);        entidad2 = new Entidad2(R.drawable.patatas_deluxe_especiadas_70523_300_150, "Entrecot", " 15 min.", 2, 50);        entidad3 = new Entidad2(R.drawable.tomate, "Hamburguesa", " 2 min.", 5, 100);        listItems.add(entidad1);        listItems.add(entidad2);        listItems.add(entidad3);        adaptor = new Adaptador2(listItems, this);        recyclerView1.setAdapter(adaptor);        adaptor.notifyDataSetChanged();        pickEntidad();    }    @Override    public void OnRecipe(int priority) {        if (priority == 20) {            Intent in = new Intent(this, Solomillo.class);            startActivity(in);        }        if (priority == 50) {            Intent in = new Intent(this, Entrecot.class);            startActivity(in);        }    }}

Answer 1

我的理解是，您想以不同的显示机会随机显示 Entidad 列表中的单个 Entidad 对象。

例如：在您的 Entidad 对象上创建一个名为 Priority 的整数字段。将第一个 Entidad 的优先级设置为 50，第二个 200，第三个 350。创建以下方法以根据优先级随机选择。（在创建它们后将 Entidad 对象的引用保存在主活动中。）

编辑：Entidad.java

public class Entidad {

private int imgFoto;

private String titulo;

private String tiempo;

private int ratingBar;

private int colorfondo;

private int priority;

public Entidad(int imgFoto, String titulo, String tiempo, int ratingBar, int colorfondo, int priority) {

    this.imgFoto = imgFoto;

    this.titulo = titulo;

    this.tiempo = tiempo;

    this.ratingBar = ratingBar;

    this.colorfondo = colorfondo;

    this.priority = priority;

}

public int getRatingBar() {

    return ratingBar;

}

public int getPriority() {

    return priority;

}

public int getImgFoto() {

    return imgFoto;

}

public String getTitulo() {

    return titulo;

}

public String getTiempo() {

    return tiempo;

}

public int getRating() { return ratingBar; }

public int getColorfondo() {

    return colorfondo;

}

}

编辑 2：使用 getEntidad()

public class Comida extends AppCompatActivity implements Adaptador.OnRecipeListener {

private RecyclerView recyclerView1;

List<Entidad> listItems;

Adaptador adaptor;

private Entidad entidad1,entidad2,entidad3;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_comida);

    recyclerView1 = findViewById(R.id.lv_1);

    LinearLayoutManager layoutManager = new 

    LinearLayoutManager(this);

    layoutManager.setOrientation(LinearLayoutManager.VERTICAL);

    recyclerView1.setLayoutManager(layoutManager);

    listItems = new ArrayList<>();

//Initialize entidad objects and keep references of them to use in pickEntidad() method

   entidad1 = new Entidad(R.drawable.calabacines_3, "Solomillo a la plancha", " 10 min.", 4, R.drawable.color_carnes,50);

   entidad2 = new Entidad(R.drawable.patatas_deluxe_especiadas_70523_300_150, "Entrecot", " 15 min.", 2, R.drawable.color_carnes,200);

    entidad3 = new Entidad(R.drawable.tomate, "Hamburguesa", " 2 min.", 5, R.drawable.color_carnes,350);

    listItems.add(entidad1);

    listItems.add(entidad2); 

    listItems.add(entidad3);

    adaptor = new Adaptador(listItems, this);

    recyclerView1.setAdapter(adaptador);

    adaptor.notifyDataSetChanged();

//Call pickEntidad() to randomly pick one entidad and show on the list

    pickEntidad();

}

@Override

public void OnRecipe(int position) {

    if (position == 0) {

        Intent in = new Intent(this, Solomillo.class);

        startActivity(in);

    }

}

private void pickEntidad(){

//Generates random int value between 0-350

final int random = new Random().nextInt(351);

//get priorities from your created Entidad objects.

int priority1 = entidad1.getPriority();

int priority2 = entidad2.getPriority();

int priority3 = entidad3.getPriority();

listItems.clear()

//Pick one randomly depending on priority

if(random < priority1){

listItems.add(entidad1)

}else if(random < priority2){

listItems.add(entidad2)

}else if (random <= priority3){

listItems.add(entidad3)

}

//update your adapter

adaptor.notifyDataSetChanged()

}

}

每次您想刷新列表时，调用此 pickEntidad() 方法。不过，这是一种硬编码方法，如果您有太多项目并且不知道优先级值或范围，它将毫无用处。您还可以通过生成 0-351 之间的整数来随机设置项目优先级。希望我能正确理解你的问题。

另外，不要给变量名加上大写字母。将您的“适配器”变量更改为“适配器”