【发布时间】：2016-10-23 18:00:28
【问题描述】：
我正在解析一个 JSon 文件，其中包含 5 支足球队，每支球队都打了 4 场比赛。
我创建了一个 Wrapper 类 OutputClass 来存储每支球队的所有详细信息，即比赛、获胜、平局和失败的数量。
由于有 5 个团队，我创建了一个 OutputClass 列表。
所以在将值传递给onPostExecute 之后，我调用了一个名为FootballAdapter 的适配器。
此适配器仅执行一次。
即使我将 outputClassList.get(int position) 中的位置值更改为 2 或 3，我在 Toast 中也会得到相同的结果，如下图所示。
我检查了outputClassList 是否为空，但不是。
Objects 是一个列表，传递自：
FootballAdapter adapter= new FootballAdapter(getApplicationContext(),R.layout.row,result);
jsonList.setAdapter(adapter);
以上代码在AsyncTask的onPostExecute方法中。
public class JSONTask extends AsyncTask<String,String,List<OutputClass>> {
@Override
protected List<OutputClass> doInBackground(String... params) {
HttpURLConnection connection=null;
BufferedReader r=null;
try {
URL url=new URL(params[0]);
connection=(HttpURLConnection)url.openConnection();
connection.connect();
InputStream stream= connection.getInputStream();
r= new BufferedReader(new InputStreamReader((stream)));
StringBuffer stringBuffer=new StringBuffer();
String line="";
while((line=r.readLine())!=null){
stringBuffer.append(line);
}
String finalJSON=stringBuffer.toString();
/// read and parse JSON file for desired output.....
JSONObject parentObject= new JSONObject(finalJSON);
// gets the name of all the objects namels alpha, bravo charlie etc etc
JSONArray names=parentObject.names();
// multiple objets for each team.....
List<OutputClass> outputClassList =new ArrayList<>();
String games[]=new String[4];
int finalScore[]=new int[names.length()];
int gd[]=new int[names.length()];
int won[]=new int[names.length()];
int draw[]=new int[names.length()];
int lost[]=new int[names.length()];
JSONObject[] mainObject=new JSONObject[names.length()];
for(int i=0;i<names.length();i++){
String teamName=names.getString(i);
mainObject[i]=parentObject.getJSONObject(teamName);
//outputClass[i].name=teamName;
// Gets the game data for each game....
games[0]=mainObject[i].getString("match_1");
games[1]=mainObject[i].getString("match_2");
games[2]=mainObject[i].getString("match_3");
games[3]=mainObject[i].getString("match_4");
// Calculates the final score and goal difference for each team.
for(int j=0;j<4;j++) {
String score[] = games[j].split("-");
int score1 = Integer.parseInt(score[0]);
int score2 = Integer.parseInt(score[1]);
if (score1 > score2) {
finalScore[i] += 3;
won[i]++;
}
else if (score1 == score2) {
finalScore[i] += 1;
draw[i]++;
}else{
lost[i]++;
}
gd[i]+=score1-score2;
}
// Calculating the position based on final score and Goal Difference...
OutputClass outputClass=new OutputClass();
outputClass.goalDifference=gd[i];
outputClass.draw=draw[i];
outputClass.finalScore=finalScore[i];
outputClass.lost=lost[i];
outputClass.won=won[i];
outputClass.played=4;
outputClass.name=teamName;
outputClassList.add(outputClass);
}
//Arrays.sort(outputClass,OutputClass.FinalScoreComparator);
//Arrays.sort(outputClass,new OutputClass().FinalScoreComparator);
Collections.sort(outputClassList,new OutputClass().FinalScoreComparator);
Log.i(TAG,"Final Scre: "+outputClassList.get(0).finalScore+" won : "+outputClassList.get(0).won);
Log.i(TAG,"Final Scre: "+outputClassList.get(1).finalScore+" won : "+outputClassList.get(1).won);
Log.i(TAG,"Final Scre: "+outputClassList.get(2).finalScore+" won : "+outputClassList.get(2).won);
Log.i(TAG,"Final Scre: "+outputClassList.get(3).finalScore+" won : "+outputClassList.get(3).won);
//return stringBuffer.toString();
return outputClassList;
} catch (MalformedURLException e) {
e.printStackTrace();
}catch (IOException e){
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
if(connection != null)
connection.disconnect();
try {
if(r!=null)
r.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPostExecute(List<OutputClass> result){
super.onPostExecute(result);
FootballAdapter adapter= new FootballAdapter(getApplicationContext(),R.layout.row,result);
jsonList.setAdapter(adapter);
//to remove the button and text view after clicking them...
imageButton.setVisibility(View.GONE);
jsonData.setVisibility(View.GONE);
//showing the list.....
setContentView(jsonList);
}
}
public class FootballAdapter extends ArrayAdapter<OutputClass>{
private List<OutputClass> outputClassList;
private int resource;
private LayoutInflater inflater;
public FootballAdapter(Context context, int resource, List<OutputClass> objects) {
super(context, resource, objects);
outputClassList = objects;
this.resource=resource;
inflater =(LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
}
@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView== null)
convertView=inflater.inflate(R.layout.row,null);
TextView rank;
TextView played;
TextView won;
TextView lost;
TextView draw;
TextView gd;
rank=(TextView)findViewById(R.id.rank);
played=(TextView)findViewById(R.id.played);
won=(TextView)findViewById(R.id.won);
lost=(TextView)findViewById(R.id.lost);
draw=(TextView)findViewById(R.id.draw);
gd=(TextView)findViewById(R.id.gd);
if(rank!=null)
played.setText("Played: " + outputClassList.get(position).played);
if(won!=null)
won.setText("Won: " + outputClassList.get(position).won);
if(lost!=null)
lost.setText("Lost: " + outputClassList.get(position).lost);
if(draw!=null)
draw.setText("Draw: " + outputClassList.get(position).draw);
if(gd!=null)
gd.setText("Goal Diff: " + outputClassList.get(position).goalDifference);
Toast toast=Toast.makeText(getApplicationContext(),"Played: "+outputClassList.get(4).played+"Won: "+outputClassList.get(4).won,Toast.LENGTH_LONG);
toast.show();
return convertView;
}
}
这是我创建的日志文件，用于检查 outputClassList 是否为空：
I/enpFootball: Final Scre: 8 won : 2
I/enpFootball: Final Scre: 7 won : 2
I/enpFootball: Final Scre: 7 won : 2
I/enpFootball: Final Scre: 5 won : 1
ListView 的片段如下图所示：
【问题讨论】：
标签： java android android-asynctask android-arrayadapter