【发布时间】：2019-05-19 14:46:53
【问题描述】：
我有一个应用程序可以解析 JSON 数据并将其显示到回收站视图中。回收器视图中的每个项目都是 Reps 类的对象，并包含在卡片布局中。当我只尝试解析字符串变量时，代码工作正常。
当我尝试将图像 URL 解析到 ImageView 中时，回收器视图不显示并且活动为空白。我正在使用 Picasso 将图像加载到我的适配器类中的 onBinfViewHolder 方法中。这是相关代码
代表：
public class Reps {
private String officeName;
private String officialName;
private String party;
private String photoUrl;
//continue to develop this with other values such as phone, photo, address etc.
public Reps(String officeName, String officialName, String party, String photoUrl) {
this.officeName = officeName;
this.officialName = officialName;
this.party = party;
this.photoUrl = photoUrl;
}
public Reps(String officeName, String officialName, String party) {
this.officeName = officeName;
this.officialName = officialName;
this.party = party;
}
public Reps(String officeName) {
this.officeName = officeName;
}
public Reps(String name, String party) {
this.officialName = name;
this.party = party;
}
public String getOfficeName() {
return officeName;
}
public void setOfficeName(String officeName) {
this.officeName = officeName;
}
public String getOfficialName() {
return officialName;
}
public void setOfficialName(String officialName) {
this.officialName = officialName;
}
public String getParty() {
return party;
}
public void setParty(String party) {
this.party = party;
}
public String getPhotoUrl() {
return photoUrl;
}
public void setPhotoUrl(String photoUrl) {
this.photoUrl = photoUrl;
}
}
RepRvAdapter：
public class RepRvAdapter extends
RecyclerView.Adapter<RepRvAdapter.MyViewHolder> {
private Context context;
private List<Reps> repsList;
RequestOptions option;
public RepRvAdapter() {
}
public RepRvAdapter(List<Reps> repList, Context applicationContext) {
this.repsList = repList;
this.context = applicationContext;
}
@NonNull
@Override
public RepRvAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view;
LayoutInflater mInflater = LayoutInflater.from(context);
view = mInflater.inflate(R.layout.card, viewGroup, false); //Inflate view to card.xml
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull RepRvAdapter.MyViewHolder myViewHolder, int i) {
myViewHolder.officeName.setText(repsList.get(i).getOfficeName()); //Display these three elements in the card view
myViewHolder.officialName.setText(repsList.get(i).getOfficialName());
myViewHolder.party.setText(repsList.get(i).getParty());
//load image into card view
Picasso.get()
.load(repsList.get(i).getPhotoUrl())
.centerCrop()
.transform(new CircleTransform(50, 0))
.fit()
.into(myViewHolder.photoUrl);
}
@Override
public int getItemCount() {
return repsList.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
//Variables
TextView officeName, officialName, party; //Only the Referendum title and type will be in the recycler view
ImageView photoUrl;
public MyViewHolder(View itemView){
super(itemView);
officeName = itemView.findViewById(R.id.office_name);
officialName = itemView.findViewById(R.id.official_name);
party = itemView.findViewById(R.id.party);
photoUrl = itemView.findViewById(R.id.photo_url);
}
}
}
解析JSON数据的方法：
//fetch json data from Civic API
private void getData(){
final ProgressDialog progressDialog = new ProgressDialog(this);
progressDialog.setMessage("Loading...");
progressDialog.show();
StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
progressDialog.dismiss();
try{
JSONObject jsonObject = new JSONObject(response);
//first loop through offices array. Retrieve officeName value
JSONArray officesArray = jsonObject.getJSONArray("offices"); //One array for offices
JSONArray officialsArray = jsonObject.getJSONArray("officials"); //one array for officials
for (int i = 0; i < officesArray.length(); i++){
JSONObject jsonOffices = officesArray.getJSONObject(i);
JSONObject jsonOfficials = officialsArray.getJSONObject(i);
Reps reps = new Reps (jsonOfficials.getString("name"),
jsonOfficials.getString("party"),
//jsonOfficials.getString("photoUrl")
jsonOffices.getString("name"));
repList.add(reps);
}
adapter = new RepRvAdapter(repList, getApplicationContext());
myrv.setAdapter(adapter);
}catch (JSONException e){
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("Volley", error.toString());
progressDialog.dismiss();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
现在，我将解析图像 URL 的代码行注释掉了。取消注释该行后，该活动将不再显示。如何让 Image url 被解析并显示在 ImageView 中？我认为这可能是 JSON 数据的问题。在 JSON 数组中，并未设置所有 photoUrl 字段。 API 可能不会为数组中的每个代表返回图像数据，而party、name 和 office 字段始终具有值。这可能是阻止回收站视图显示的原因吗？这是一段相关的 JSON 数据：
"officials": [
{
"name": "Donald J. Trump",
"address": [
{
"line1": "The White House",
"line2": "1600 Pennsylvania Avenue NW",
"city": "Washington",
"state": "DC",
"zip": "20500"
}
],
"party": "Republican",
"phones": [
"(202) 456-1111"
],
"photoUrl":"https://www.whitehouse.gov/sites/whitehouse.gov/files/images/45/PE%20Color.jpg",
"channels": [
{
"type": "GooglePlus",
"id": "+whitehouse"
},
{
"type": "Facebook",
"id": "whitehouse"
},
{
"type": "Twitter",
"id": "potus"
},
{
"type": "YouTube",
"id": "whitehouse"
}
]
},
{
"name": "Mike Pence",
"address": [
{
"line1": "The White House",
"line2": "1600 Pennsylvania Avenue NW",
"city": "Washington",
"state": "DC",
"zip": "20500"
}
],
"party": "Republican",
"phones": [
"(202) 456-1111"
],
"photoUrl":"https://www.whitehouse.gov/sites/whitehouse.gov/files/images/45/VPE%20Color.jpg",
"channels": [
{
"type": "GooglePlus",
"id": "+whitehouse"
},
{
"type": "Facebook",
"id": "whitehouse"
},
{
"type": "Twitter",
"id": "VP"
}
]
},
{
"name": "Dianne Feinstein",
"address": [
{
"line1": "331 Hart Senate Office Building",
"city": "Washington",
"state": "DC",
"zip": "20510"
}
],
"party": "Democratic",
"phones": [
"(202) 224-3841"
],
"photoUrl": "http://bioguide.congress.gov/bioguide/photo/F/F000062.jpg",
"channels": [
{
"type": "Facebook",
"id": "SenatorFeinstein"
},
{
"type": "Twitter",
"id": "SenFeinstein"
},
{
"type": "YouTube",
"id": "SenatorFeinstein"
}
]
},
{
"name": "Kamala D. Harris",
"address": [
{
"line1": "112 Hart Senate Office Building",
"city": "Washington",
"state": "DC",
"zip": "20510"
}
],
"party": "Democratic",
"phones": [
"(202) 224-3553"
],
"channels": [
{
"type": "Twitter",
"id": "KamalaHarris"
},
{
"type": "YouTube",
"id": "UC0XBsJpPhOLg0k4x9ZwrWzw"
}
]
如您所见，所有代表都有姓名、政党和办公室，但并非所有代表都有图片 URL。 logcat 会返回这个关于它的信息。
我愿意尝试不同的库。如果您需要查看更多代码，请告诉我。感谢您的帮助！
我在我的 jsonParse 方法中添加了以下条件来说明没有 photoUrl 字段的对象。
try{
JSONObject jsonObject = new JSONObject(response);
//first loop through offices array. Retrieve officeName value
JSONArray officesArray = jsonObject.getJSONArray("offices"); //One array for offices
JSONArray officialsArray = jsonObject.getJSONArray("officials"); //one array for officials
for (int i = 0; i < officesArray.length(); i++){
JSONObject jsonOffices = officesArray.getJSONObject(i);
JSONObject jsonOfficials = officialsArray.getJSONObject(i);
if(jsonOfficials.has("photoUrl")){
Reps reps = new Reps (jsonOfficials.getString("name"),
jsonOfficials.getString("party"),
jsonOfficials.getString("photoUrl"),
jsonOffices.getString("name"));
repList.add(reps);
}else{
Reps reps = new Reps(jsonOfficials.getString("name"),
jsonOfficials.getString("party"),
jsonOffices.getString("name"));
repList.add(reps);
}
}
adapter = new RepRvAdapter(repList, getApplicationContext());
myrv.setAdapter(adapter);
使用此代码，recycler 视图显示，但图像 URL 字符串显示在 officeName 文本视图中，而不是 ImageView 中的图像。
由于上次官方没有图片，所以他们的数据显示正确。
【问题讨论】：
-
让你检查 logcat 是否有任何错误还有你在清单文件中添加了互联网权限
-
@Gabriel 在添加加载之前尝试解析你的 uri，使用
Uri.parse(repsList.get(i).getPhotoUrl()) -
@NileshRathod Internet 权限已关闭。 logcat 说 JSONException: No value for photoUrl
标签： android json parsing android-recyclerview picasso