将向日葵应用程序ViewModel更改为只显示植物列表？

Question

我正在尽我最大的努力使用谷歌的向日葵应用程序作为我的应用程序的基础，如何改变对变量"growZoneNumber“的依赖，使其只返回所有植物？

这是从google官方kotlin版本转换过来的java代码：

package com.google.samples.apps.sunflower.viewmodels;

import com.google.samples.apps.sunflower.data.Plant;
import com.google.samples.apps.sunflower.data.PlantRepository;

import java.util.List;

import androidx.annotation.NonNull;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.Transformations;
import androidx.lifecycle.ViewModel;

/**
 * Created by Shawn Wang on 3/26/19.
 */
public class PlantListViewModel extends ViewModel {
    private static final int NO_GROW_ZONE = -1;

    private PlantRepository plantRepository;

    private MutableLiveData<Integer> growZoneNumber;

    public LiveData<List<Plant>> plants;

    PlantListViewModel(@NonNull PlantRepository plantRepository) {
        super();
        this.plantRepository = plantRepository;
        this.growZoneNumber = new MutableLiveData<>(-1);
        this.plants = Transformations.switchMap(growZoneNumber, it -> {
            if (it == NO_GROW_ZONE) {
                return this.plantRepository.getPlants();
            } else {
                return this.plantRepository.getPlantsWIthGrowZoneNumber(it);
            }
        });
    }

    public void setGrowZoneNumber(int num) {
        this.growZoneNumber.setValue(num);
    }

    public void cleanGrowZoneNumber() {
        this.growZoneNumber.setValue(NO_GROW_ZONE);
    }

    public boolean isFiltered() {
        return this.growZoneNumber.getValue() != NO_GROW_ZONE;
    }
}

谢谢。

Answer 1

我花了一段时间才弄明白，但找到了答案(当然，内部的模型略有不同

公共类PinViewModel扩展了ViewModel {

private PinRepository pinRepository;

PinViewModel(@NonNull PinRepository pinRepository) {
    this.pinRepository = pinRepository;
}

public LiveData<List<Pin>> getPins() {
    return pinRepository.getPins();
}

}