Question

Overflowers，

在我的项目中，我将一个带有名称和分数的JSON对象发送到servlet，该响应是一个JSON的高分榜。然后我使用GSON将列表转换为ArrayList，并将set作为我的hiscoreList在我的适配器中用于listview。这一切都正常，除非我尝试设置convertView的文本时它会给出一个nullpointer异常。

这是我的适配器代码：

public class HighscoreAdapter extends ArrayAdapter<HighscoreItem>{

    public HighscoreAdapter(Context context, ArrayList<HighscoreItem> items){
        super(context, 0, items);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent){
        final HighscoreItem item = getItem(position);

        if(convertView == null){
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.highscore_item, parent, false);
        }

        TextView name = (TextView) findViewById(R.id.thename);
        TextView score = (TextView) findViewById(R.id.thescore);

        name.setText(item.getName());                        << NullPointer
        score.setText(String.valueOf(item.getScore()));      << NullPointer

        return convertView;
    }
}

我的onCreate：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_high_score);

    ListView highscoreListView = (ListView) findViewById(R.id.list);
    highscoreList = new ArrayList<HighscoreItem>();

    adapter = new HighscoreAdapter(getBaseContext(), highscoreList);
    highscoreListView.setAdapter(adapter);

    Button button = (Button) findViewById(R.id.sendButton);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            try {
                sendMyScore();
            } catch (JSONException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

我如何设置列表：

Gson gson = new Gson();
HighscoreItem[] highscoreItems = gson.fromJson(test, HighscoreItem[].class);

highscoreList.clear();
for(int i = 0; i < highscoreItems.length; i++){
    highscoreList.add(highscoreItems[i]);
}
adapter.notifyDataSetChanged();

错误日志：

06-24 22:03:39.591  15162-15162/com.example.lucschuttel.infraandsec E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.lucschuttel.infraandsec, PID: 15162
java.lang.NullPointerException
        at com.example.lucschuttel.infraandsec.HighScoreActivity$HighscoreAdapter.getView(HighScoreActivity.java:82)
        at android.widget.AbsListView.obtainView(AbsListView.java:2738)
        at android.widget.ListView.measureHeightOfChildren(ListView.java:1274)
        at android.widget.ListView.onMeasure(ListView.java:1186)
        at android.view.View.measure(View.java:17495)

Answer 1

您应该致电convertView.findViewById(R.id.thename);而不仅仅是findViewById。

如果不能解决问题，请同时发布您的xml文件。

Answer 2

而不是使用

TextView name = (TextView) findViewById(R.id.thename);
TextView score = (TextView) findViewById(R.id.thescore);

使用

TextView name = (TextView)  convertView.findViewById(R.id.thename);
TextView score = (TextView) convertView.findViewById(R.id.thescore);

TextView不会在ListView适配器中设置setText（）

2 个答案: