我正在编写与汽车分类API交互的应用程序。我想要两个窗口：一个窗口，用户在其中键入所需的汽车，另一个窗口中显示结果。
我的API返回一个大的JSON文件，每辆车大约有40个参数，其中只有大约20个对我感兴趣。我有一个自定义类来存储API返回的一些数据。在此类的构造函数（称为CarListing）中，我传递了一个JSONObject并在构造函数中进行了JSON解析。
然后在一个线程化的HttpGet活动内部调用该类，该活动本身由MainActivity调用。因此，对于给定的搜索，我希望从API中获得多个结果。我能够成功地将自定义对象返回给MainActivity，但是在将数据从MainActivity发送到SecondActivity时遇到了问题。最终，我想将HashMap传递给适配器，以便可以在自己制作的自定义布局中使用它。
我在Internet上看到的大多数响应都涉及使用Parcelable，但我不认为JSONObject（就此而言，也不是HashMap）是Parcelable对象。我曾尝试在CarListing类中实现此功能，但Android Studio不喜欢我将JSONObject作为构造函数对象传递。
那么使我的自定义对象可拆分的最佳方法是什么？我是否应该在构造函数之外（即在我的HttpGet线程中）进行JSON解析，然后将所有20-25个值作为参数传递？我认为我最大的问题是关于构造函数，但我可能是错误的。感谢您的帮助，如有必要，我可以提供更多信息。
这是我的自定义对象CarListing的代码：
package com.example.carsearchapp;
import android.os.Parcel;
import android.os.Parcelable;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.io.Serializable;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.HashMap;
public class CarListing
{
/* vehicle parameters */
String make, model, trim, vin, color, condition, transmission, engine, drivetype, seller_type, seller_name, website, city, state;
int year, price, mileage, cylinders;
double distance;
ArrayList<String> images;
/* carfax parameters */
boolean one_owner, clean_title;
/* local variables that may be important */
int index;
JSONObject img_json, build, dealer;
JSONArray img_array;
public HashMap<String, String> listview_hashmap;
/* Most strings are default N/A. Most integers are default 1, or 1970 for the case of years. */
public CarListing(JSONObject input, int index)
{
try
{
this.images = new ArrayList<>();
this.index = index;
this.listview_hashmap = new HashMap<>();
if(input.has("vin")) this.vin = input.getString("vin");
else this.vin = "N/A";
if(input.has("price")) this.price = input.getInt("price");
else this.price = 1;
if(input.has("mileage")) this.mileage = input.getInt("mileage");
else this.mileage = 1;
if(input.has("vdp_url")) this.website = input.getString("vdp_url");
else this.website = "N/A";
if(input.has("carfax_1_owner")) this.one_owner = input.getBoolean("carfax_1_owner");
else this.one_owner = true;
if(input.has("carfax_clean_title")) this.clean_title = input.getBoolean("carfax_clean_title");
else this.clean_title = true;
if(input.has("exterior_color")) this.color = input.getString("exterior_color");
else this.color = "N/A";
if(input.has("seller_type")) this.seller_type = input.getString("seller_type");
else this.seller_type = "N/A";
if(input.has("inventory_type")) this.condition = input.getString("inventory_type");
else this.condition = "N/A";
if(input.has("build"))
{
this.build = input.getJSONObject("build");
if(this.build.has("year")) this.year = this.build.getInt("year");
else this.year = 1970;
if(this.build.has("make")) this.make = this.build.getString("make");
else this.make = "N/A";
if(this.build.has("model")) this.model = this.build.getString("model");
else this.model = "N/A";
if(this.build.has("trim")) this.trim = this.build.getString("trim");
else this.trim = "N/A";
if(this.build.has("transmission")) this.transmission = this.build.getString("transmission");
else this.transmission = "N/A";
if(this.build.has("drivetrain")) this.drivetype = this.build.getString("drivetrain");
else this.drivetype = "N/A";
if(this.build.has("cylinders")) this.cylinders = this.build.getInt("cylinders");
else this.cylinders = 4;
if(this.build.has("engine")) this.engine = this.build.getString("engine");
else this.engine = "N/A";
if(this.build.has("dist")) this.distance = this.build.getDouble("dist");
else this.distance = 0;
}
if(input.has("dealer"))
{
this.dealer = input.getJSONObject("dealer");
if(this.dealer.has("name")) this.seller_name = capitalizeLetters(this.dealer.getString("name"));
else this.seller_name = "N/A";
if(this.dealer.has("city")) this.city = this.dealer.getString("city");
else this.city = "N/A";
if(this.dealer.has("state")) this.state = this.dealer.getString("state");
else this.state = "N/A";
}
if(input.has("media"))
{
this.img_json = input.getJSONObject("media");
if(this.img_json.has("photo_links")) this.img_array = this.img_json.getJSONArray("photo_links");
else this.img_json = null;
int n = this.img_array.length();
for(int i=0;i<n;i++)
{
if(i >= 50) break;
else
{
this.images.add(img_array.getString(i));
}
}
}
}
catch(JSONException ex)
{
System.out.println("JSON Exception thrown");
}
}
public String capitalizeLetters(String input)
{
String[] array = input.split(" ");
String output = "";
int n = array.length;
for(int i=0;i<n;i++)
{
String cap = array[i].substring(0, 1).toUpperCase() + array[i].substring(1);
output += cap;
}
return output;
}
public void makeHashMap()
{
String vehicle_title = Integer.toString(this.year) + this.make + this.model + this.trim;
String vehicle_information = NumberFormat.getIntegerInstance().format(this.mileage) + " miles | " + this.color + " | " + this.condition + " | $" + NumberFormat.getIntegerInstance().format(this.price);
String dealer_name = this.seller_name;
String location = Double.toString(this.distance) + " mi. | " + this.city + ", " + this.state;
String first_img = this.images.get(0);
this.listview_hashmap.put("title", vehicle_title);
this.listview_hashmap.put("information", vehicle_information);
this.listview_hashmap.put("dealer", dealer_name);
this.listview_hashmap.put("distance", location);
this.listview_hashmap.put("first_image", first_img);
}
}
答案 0 :(得分：0)
解决了！我必须在该类中添加四个主要参数，以使其可打包。
第一个是一个受保护的构造函数，其中包含一个Parcel对象。
第二个是一个新的静态CREATOR对象，它具有内部方法createFromParcel和newArray。
第三个是describeContents函数。
最后是writeToParcel函数。
希望其他人能够从中学到东西，对不起，如果这可以被认为是转贴！
修改后的代码如下：
package com.example.marketcheckcarsearchapp;
import android.os.Parcel;
import android.os.Parcelable;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.io.Serializable;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.HashMap;
public class CarListing implements Parcelable
{
/* vehicle parameters */
String make, model, trim, vin, color, condition, transmission, engine, drivetype, seller_type, seller_name, website, city, state;
int year, price, mileage, cylinders;
double distance;
ArrayList<String> images;
/* carfax parameters */
boolean one_owner, clean_title;
/* local variables that may be important */
int index;
JSONObject img_json, build, dealer;
JSONArray img_array;
public HashMap<String, String> listview_hashmap;
/* Most strings are default N/A. Most integers are default 1, or 1970 for the case of years. */
public CarListing(JSONObject input, int index)
{
try
{
this.images = new ArrayList<>();
this.index = index;
this.listview_hashmap = new HashMap<>();
if(input.has("vin")) this.vin = input.getString("vin");
else this.vin = "N/A";
if(input.has("price")) this.price = input.getInt("price");
else this.price = 1;
if(input.has("mileage")) this.mileage = input.getInt("mileage");
else this.mileage = 1;
if(input.has("vdp_url")) this.website = input.getString("vdp_url");
else this.website = "N/A";
if(input.has("carfax_1_owner")) this.one_owner = input.getBoolean("carfax_1_owner");
else this.one_owner = true;
if(input.has("carfax_clean_title")) this.clean_title = input.getBoolean("carfax_clean_title");
else this.clean_title = true;
if(input.has("exterior_color")) this.color = input.getString("exterior_color");
else this.color = "N/A";
if(input.has("seller_type")) this.seller_type = input.getString("seller_type");
else this.seller_type = "N/A";
if(input.has("inventory_type")) this.condition = input.getString("inventory_type");
else this.condition = "N/A";
if(input.has("build"))
{
this.build = input.getJSONObject("build");
if(this.build.has("year")) this.year = this.build.getInt("year");
else this.year = 1970;
if(this.build.has("make")) this.make = this.build.getString("make");
else this.make = "N/A";
if(this.build.has("model")) this.model = this.build.getString("model");
else this.model = "N/A";
if(this.build.has("trim")) this.trim = this.build.getString("trim");
else this.trim = "N/A";
if(this.build.has("transmission")) this.transmission = this.build.getString("transmission");
else this.transmission = "N/A";
if(this.build.has("drivetrain")) this.drivetype = this.build.getString("drivetrain");
else this.drivetype = "N/A";
if(this.build.has("cylinders")) this.cylinders = this.build.getInt("cylinders");
else this.cylinders = 4;
if(this.build.has("engine")) this.engine = this.build.getString("engine");
else this.engine = "N/A";
if(this.build.has("dist")) this.distance = this.build.getDouble("dist");
else this.distance = 0;
}
if(input.has("dealer"))
{
this.dealer = input.getJSONObject("dealer");
if(this.dealer.has("name")) this.seller_name = capitalizeLetters(this.dealer.getString("name"));
else this.seller_name = "N/A";
if(this.dealer.has("city")) this.city = this.dealer.getString("city");
else this.city = "N/A";
if(this.dealer.has("state")) this.state = this.dealer.getString("state");
else this.state = "N/A";
}
if(input.has("media"))
{
this.img_json = input.getJSONObject("media");
if(this.img_json.has("photo_links")) this.img_array = this.img_json.getJSONArray("photo_links");
else this.img_json = null;
int n = this.img_array.length();
for(int i=0;i<n;i++)
{
if(i >= 50) break;
else
{
this.images.add(img_array.getString(i));
}
}
}
}
catch(JSONException ex)
{
System.out.println("JSON Exception thrown");
}
}
protected CarListing(Parcel in) {
make = in.readString();
model = in.readString();
trim = in.readString();
vin = in.readString();
color = in.readString();
condition = in.readString();
transmission = in.readString();
engine = in.readString();
drivetype = in.readString();
seller_type = in.readString();
seller_name = in.readString();
website = in.readString();
city = in.readString();
state = in.readString();
year = in.readInt();
price = in.readInt();
mileage = in.readInt();
cylinders = in.readInt();
distance = in.readDouble();
images = in.createStringArrayList();
one_owner = in.readByte() != 0;
clean_title = in.readByte() != 0;
index = in.readInt();
}
public static final Creator<CarListing> CREATOR = new Creator<CarListing>() {
@Override
public CarListing createFromParcel(Parcel in) {
return new CarListing(in);
}
@Override
public CarListing[] newArray(int size) {
return new CarListing[size];
}
};
public String capitalizeLetters(String input)
{
String[] array = input.split(" ");
String output = "";
int n = array.length;
for(int i=0;i<n;i++)
{
String cap = array[i].substring(0, 1).toUpperCase() + array[i].substring(1);
output += cap;
}
return output;
}
public void makeHashMap()
{
String vehicle_title = Integer.toString(this.year) + this.make + this.model + this.trim;
String vehicle_information = NumberFormat.getIntegerInstance().format(this.mileage) + " miles | " + this.color + " | " + this.condition + " | $" + NumberFormat.getIntegerInstance().format(this.price);
String dealer_name = this.seller_name;
String location = Double.toString(this.distance) + " mi. | " + this.city + ", " + this.state;
String first_img = this.images.get(0);
this.listview_hashmap.put("title", vehicle_title);
this.listview_hashmap.put("information", vehicle_information);
this.listview_hashmap.put("dealer", dealer_name);
this.listview_hashmap.put("distance", location);
this.listview_hashmap.put("first_image", first_img);
}
@Override
public int describeContents()
{
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(make);
dest.writeString(model);
dest.writeString(trim);
dest.writeString(vin);
dest.writeString(color);
dest.writeString(condition);
dest.writeString(transmission);
dest.writeString(engine);
dest.writeString(drivetype);
dest.writeString(seller_type);
dest.writeString(seller_name);
dest.writeString(website);
dest.writeString(city);
dest.writeString(state);
dest.writeInt(year);
dest.writeInt(price);
dest.writeInt(mileage);
dest.writeInt(cylinders);
dest.writeDouble(distance);
dest.writeStringList(images);
dest.writeByte((byte) (one_owner ? 1 : 0));
dest.writeByte((byte) (clean_title ? 1 : 0));
dest.writeInt(index);
}
}