Java 无法迭代对共享首选项的Android字符串引用？

所以我有一个名为locationsList的ArrayList。我还拥有共享引用，其中包含在上一个活动中设置的城市名称，我希望将其添加到我的ArrayList中。但我想在它的末尾添加一个>。比如说

SharedPreferences prefs = getActivity().getSharedPreferences("prefs", 0);
locationsList.add(0, prefs.getString("city", "no city") + ">");

但是它不会改变！！！。>没有被添加。我甚至在设置textView的文本时尝试添加它

TextView tv...;
tv.setText(locationsList.get(0) + ">");

我不明白为什么它不能改变。显然，数组列表包含对首选项的引用，并且不能更改。但我甚至尝试将首选项分配给一个字符串变量，然后对其进行迭代，它不会改变。有人能帮我吗

活动中的异步

class getLocationsUrl extends AsyncTask<String, String, String> {

    ArrayList<String> tempList = new ArrayList<String>();

    @Override
    protected String doInBackground(String... arg0) {

        ArrayList<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("city", prefs.getString("city", "durban")));

        JSONParser parser = new JSONParser();
        JSONObject json = parser.makeHttpRequest(IMAGE_URL + "fetchlocations.php", "POST",   
params);

        try {

            list = json.getJSONArray("posts");

            for(int i = 0; i < list.length(); i++) {
                JSONObject c = list.getJSONObject(i);
                String location = c.getString("location");

                tempList.add(location);
                Log.d("async trend", trendList.get(0));
            }

            Log.d("Got list", imageUrl.get(0) + " " + trendList.get(0));

        } catch(JSONException je) {
            Log.d("json exception", "json exception");
            je.printStackTrace();   
        }
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        locationsList = tempList;
        locationsFragment.updateAdapter();
        feedFragment.updateHeadingAdapter();
    }
}

从异步调用FeedFragment的updateHeadingAdapter

    public void updateHeadingAdapter() {
    headingList = (ArrayList<String>) NightWatch.locationsList.clone();
    headingList.add(0, (prefs.getString("city", "null") + ">"));
    headingAdapter = new CustomHeadingPagerAdapter(getChildFragmentManager());
    headingPager.setAdapter(headingAdapter);
}

最后是我在适配器中返回的HeadingFragment

   package info.nightowl.nightowl;

import java.util.ArrayList;

import com.example.nightowl.R;

import android.content.SharedPreferences;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class HeadingFragment extends Fragment{

int position;
Typeface font;
ArrayList<String> list;
SharedPreferences prefs;

static HeadingFragment newInstance(int position, ArrayList<String> list) {

    final HeadingFragment f = new HeadingFragment();
    Bundle args = new Bundle();
    args.putInt("position", position);
    args.putStringArrayList("list", list);

    f.setArguments(args);
    return f;
}

@Override
public void onCreate(Bundle savedInstanceState) {

    position = getArguments().getInt("position");
    list = getArguments().getStringArrayList("list");
    prefs = getActivity().getSharedPreferences("prefs", 0);
    font = Typeface.createFromAsset(getActivity().getAssets(),
            "NotCourierSans.ttf");

    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View v = inflater.inflate(R.layout.heading_viewpage_layout, null);

    TextView tv = (TextView) v.findViewById(R.id.headingText);

    if(position == 0) tv.setText(">" + list.get(position) + ">");
    else tv.setText(list.get(position) + ">");

    tv.setTypeface(font);
    tv.setTextColor(Color.YELLOW);
    tv.setTextSize(30);


    return v;

}
}

---

我明白了。始终记住，当迭代到字符串文本vi时，您将其设置为xml中的一行，以便

android:singleLine="true"

---

这真是一个愚蠢的错误

你能发布更多的代码吗？/你的代码没有错。@RolfSmit但肯定有错。为什么它没有改变！！！。当我说tv.setText是在开始的时候？？？我怀疑你的新代码是如何不编译成一个新的APK文件而运行旧文件的？会是这样吗？在我的环境中运行这段代码效果很好；Log.dTest，test+>；首先，单词是附加的，而不是迭代的。作为一种解决方案，这种改变并不十分可信——相反，它看起来像是与最终让您测试实际源代码的东西的随机巧合。

   package info.nightowl.nightowl;

import java.util.ArrayList;

import com.example.nightowl.R;

import android.content.SharedPreferences;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class HeadingFragment extends Fragment{

int position;
Typeface font;
ArrayList<String> list;
SharedPreferences prefs;

static HeadingFragment newInstance(int position, ArrayList<String> list) {

    final HeadingFragment f = new HeadingFragment();
    Bundle args = new Bundle();
    args.putInt("position", position);
    args.putStringArrayList("list", list);

    f.setArguments(args);
    return f;
}

@Override
public void onCreate(Bundle savedInstanceState) {

    position = getArguments().getInt("position");
    list = getArguments().getStringArrayList("list");
    prefs = getActivity().getSharedPreferences("prefs", 0);
    font = Typeface.createFromAsset(getActivity().getAssets(),
            "NotCourierSans.ttf");

    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View v = inflater.inflate(R.layout.heading_viewpage_layout, null);

    TextView tv = (TextView) v.findViewById(R.id.headingText);

    if(position == 0) tv.setText(">" + list.get(position) + ">");
    else tv.setText(list.get(position) + ">");

    tv.setTypeface(font);
    tv.setTextColor(Color.YELLOW);
    tv.setTextSize(30);


    return v;

}
}

android:singleLine="true"