如何从json-java android中的对象中删除所有null和空字符串值

Question

如何从JSON java android中的对象中删除所有null和空字符串值

过滤掉任何"；name"；为空或null。

这是我的主要活动

Api api = retrofit.create(Api.class);
Call<List<MainData>> call = api.getData();
call.enqueue(new Callback<List<MainData>>() {
@Override
public void onResponse (Call<List<MainData>> call, Response<List<MainData>> response) {
if (!response.isSuccessful()) {
Toast.makeText(MainActivity.this, response.code(), Toast.LENGTH_SHORT).show();
return;
}
List<MainData> postList = response.body();


// Filter out any items where "name" is blank or null.
List<MainData> tempList = new ArrayList<>();
for(MainData data :postList)
{
if(null!= data.getName() && !data.getName().isEmpty()) {
//sort by name
Collections.sort(tempList, (mainData, t1) -> mainData.getName().compareTo(t1.getName()));
//sort by ListId
Collections.sort(tempList, (mainData, t1) -> mainData.getListId().compareTo(t1.getListId()) );
tempList.add(data);

}
}

RecyclerViewAdapter recyclerViewAdapter = new RecyclerViewAdapter(tempList, MainActivity.this);
recyclerView.setAdapter(recyclerViewAdapter);
}
@Override
public void onFailure (Call<List<MainData>> call, Throwable t) {
Toast.makeText(MainActivity.this, t.getMessage(), Toast.LENGTH_SHORT).show();
}
});

这是我的广告

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
//initialize variables
List<MainData> dataArrayList;
Context context;
//create constructor
public RecyclerViewAdapter (Context context, List<MainData> dataArrayList) {
this.dataArrayList = dataArrayList;
this.context = context;
}

@NonNull
@Override
public ViewHolder onCreateViewHolder (@NonNull ViewGroup parent, int viewType) {
//this method recycling the view holder
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_item, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder (@NonNull ViewHolder holder, int position) {
//initialize Main data
MainData data = dataArrayList.get(position);
//set name on text view
holder.listId.setText(String.format("list_id : %s", data.getListId()));
holder.name.setText(String.format("name : %s", data.getName()));
holder.id.setText(String.format("id : %s", data.getId()));
}
@Override
public int getItemCount () {
return dataArrayList.size();
}

public class ViewHolder extends RecyclerView.ViewHolder {
//initialize variables

TextView listId, name, id;
public ViewHolder (@NonNull View itemView) {
super(itemView);
//assign variables

listId = itemView.findViewById(R.id.list_id);
name = itemView.findViewById(R.id.name);
id = itemView.findViewById(R.id.id);
}
}

}

这是数据

公共类MainData｛

public String listId, name, id;

public String getListId () {
return listId;
}
public  String getName () {
return name;
}
public  String getId () {
return id;
}

}

这就是Api

public interface Api {
@GET("hiring.json")
Call<List<MainData>> getData();

}

这是我的应用程序，我想删除null和emp在此处输入图像描述

Answer 1

有两种方式

(1( 在膨胀数据时，您可以过滤这些不需要的值(2( 创建一个临时列表，然后只从主列表中添加所需的值。示例代码：

List<MainData> tempList = new ArrayList<>();
for(MainData data :postList)
{
if(null!= data.getName() && !data.getName().isEmpty())
{   tempList.add(data);
}
}

然后将这个tempList传递给适配器。

最终代码看起来是这样的。

Api api = retrofit.create(Api.class);
Call<List<MainData>> call = api.getData();
call.enqueue(new Callback<List<MainData>>() {
@Override
public void onResponse (Call<List<MainData>> call, Response<List<MainData>> response) {
if (!response.isSuccessful()) {
Toast.makeText(MainActivity.this, response.code(), Toast.LENGTH_SHORT).show();
return;
}
List<MainData> postList = response.body();
//sort by ListId
Collections.sort(postList, (mainData, t1) -> mainData.getListId().compareTo(t1.getListId()));
// Filter out any items where "name" is blank or null.
List<MainData> tempList = new ArrayList<>();
for(MainData data :postList)
{
if(null!= data.getName() && !data.getName().isEmpty())
{   tempList.add(data);
}
}

RecyclerViewAdapter recyclerViewAdapter = new RecyclerViewAdapter(MainActivity.this, tempList );
recyclerView.setAdapter(recyclerViewAdapter);
}
@Override
public void onFailure (Call<List<MainData>> call, Throwable t) {
Toast.makeText(MainActivity.this, t.getMessage(), Toast.LENGTH_SHORT).show();
}
});

}

如果有什么不清楚的地方，可以随时询问