使用 json 从 url 加载微调器

Question

我正在尝试使用 json 从 url 加载微调器值。

我使用的代码是

 private class DownloadJSON extends AsyncTask<Void, Void, Void>
    {
        protected Void doInBackground(Void... params) 
        {
            // Locate the WorldPopulation Class 
            world = new ArrayList<WorldPopulation>();
            // Create an array to populate the spinner 
            worldlist = new ArrayList<String>();
            // JSON file URL address
            jsonobject = JSONfunctions.getJSONfromURL("http://");

        //  Log.v("Load Employees",jsonobject.toString());

            try 
            {
                // Locate the NodeList name
                jsonarray = jsonobject.getJSONArray("Employees");
                for (int i = 0; i < jsonarray.length(); i++) 
                {
                    jsonobject = jsonarray.getJSONObject(i);

                    WorldPopulation worldpop = new WorldPopulation();

                    worldpop.setRank(jsonobject.optString("FirstName"));
                    worldpop.setCountry(jsonobject.optString("LastName"));
                    worldpop.setPopulation(jsonobject.optString("EmpNo"));
                    //      worldpop.setFlag(jsonobject.optString("flag"));
                    world.add(worldpop);

                    // Populate spinner with country names
                    worldlist.add(jsonobject.optString("FirstName") + "-" +jsonobject.optString("EmpNo"));

                    mySpinner.setAdapter(new ArrayAdapter<String>(VisitorEntry.this,android.R.layout.simple_spinner_dropdown_item,  worldlist));
                }
            }
            catch (Exception e) 
            { 
                //  Log.e("Error", e.getMessage());
                e.printStackTrace();
            }
            return null;
        }

此代码有时显示结果，有时不显示。我不理解这个问题，想知道是否有其他方法可以从 url 中获取值到微调器中。当我没有显示值时，出现以下错误：

04-27 14:19:25.979: W/System.err(17486): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
04-27 14:19:25.979: W/System.err(17486):    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4611)
04-27 14:19:25.979: W/System.err(17486):    at android.view.ViewRootImpl.invalidateChildInParent(ViewRootImpl.java:867)
04-27 14:19:25.979: W/System.err(17486):    at android.view.ViewGroup.invalidateChild(ViewGroup.java:4066)
04-27 14:19:25.979: W/System.err(17486):    at android.view.View.invalidate(View.java:10271)
04-27 14:19:25.979: W/System.err(17486):    at android.view.View.invalidate(View.java:10226)
04-27 14:19:25.979: W/System.err(17486):    at android.widget.AbsSpinner.resetList(AbsSpinner.java:153)
04-27 14:19:25.979: W/System.err(17486):    at android.widget.AbsSpinner.setAdapter(AbsSpinner.java:104)
04-27 14:19:25.979: W/System.err(17486):    at android.widget.Spinner.setAdapter(Spinner.java:382)
04-27 14:19:25.989: W/System.err(17486):    at com.example.wepvms.VisitorEntry$DownloadJSON1.doInBackground(VisitorEntry.java:854)
04-27 14:19:25.989: W/System.err(17486):    at com.example.wepvms.VisitorEntry$DownloadJSON1.doInBackground(VisitorEntry.java:1)
04-27 14:19:25.989: W/System.err(17486):    at android.os.AsyncTask.call(AsyncTask.java:287)
04-27 14:19:25.989: W/System.err(17486):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
04-27 14:19:25.989: W/System.err(17486):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
04-27 14:19:25.989: W/System.err(17486):    at android.os.AsyncTask$SerialExecutor.run(AsyncTask.java:230)
04-27 14:19:25.989: W/System.err(17486):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
04-27 14:19:25.989: W/System.err(17486):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
04-27 14:19:25.989: W/System.err(17486):    at java.lang.Thread.run(Thread.java:856)

Answer 1

首先你可以使用 Arraylist 来存储数据然后创建 Baseadapter class 用于显示数据..

Answer 2

你好，你可以使用一个库 GSON 这使得它更容易解析

你可以参考this他如何解析并将其添加到他的列表对象

Answer 3

我建议尝试把

mySpinner.setAdapter(new ArrayAdapter<String>(VisitorEntry.this,android.R.layout.simple_spinner_dropdown_item,  worldlist));

里面有这个runonUiThread喜欢这样

runOnUiThread(new Runnable() {
     @Override
     public void run() {

mySpinner.setAdapter(new ArrayAdapter<String>(VisitorEntry.this,android.R.layout.simple_spinner_dropdown_item,  worldlist));

    }
});

使用 json 从 url 加载微调器

loading spinner from url using json

url

android

json

spinner