我在这里包含了我的全部代码。由于某种原因，它不会进入类JsonHandler，因此我无法获取所需的数据。我似乎无法理解这里的问题。可能真的很傻。
我已经使用toast的帮助检查了它是否没有进入Json Handler类。
public class MainActivity extends Activity implements OnClickListener {
Button prem,work,tshirt,tech,ntech,query,reg,about;
String[] name,org,desc,date,time,loc,cname1,cname2,pho1,pho2,email,team,fee;
int k;
int[] tid,ftid;
String[] fname,forg,fdesc,fdate,ftime,floc,fcname1,fcname2,fpho1,fpho2,femail,fteam,ffee;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new request().execute();
prem=(Button) findViewById (R.id.button1);
about=(Button) findViewById (R.id.babout);
tshirt=(Button) findViewById (R.id.btshirt);
work=(Button) findViewById (R.id.button4);
tech=(Button) findViewById (R.id.button2);
ntech=(Button) findViewById (R.id.button5);
reg=(Button) findViewById (R.id.button3);
query=(Button) findViewById (R.id.button6);
prem.setOnClickListener(this);
about.setOnClickListener(this);
tshirt.setOnClickListener(this);
work.setOnClickListener(this);
tech.setOnClickListener(this);
ntech.setOnClickListener(this);
reg.setOnClickListener(this);
query.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()){
case R.id.babout:
break;
case R.id.btshirt:
break;
case R.id.button1:
break;
case R.id.button2:
break;
case R.id.button3:
break;
case R.id.button4:
break;
case R.id.button5:
break;
case R.id.button6:
break;
}
//Events o = null;
//o.set(ftid, fname, fdate, ffee, fcname1, fcname2, fpho1, fpho2, floc, forg, fdesc, femail, fteam, ftime);
}
private boolean isOnline() {
// TODO Auto-generated method stub
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netinfo = cm.getActiveNetworkInfo();
return netinfo!=null && netinfo.isConnected();
}
private class request extends AsyncTask<Void, Void, List<String>>{
private ProgressDialog dialog;
AndroidHttpClient client= AndroidHttpClient.newInstance("");
HttpGet request;
protected void onPreExecute() {
this.dialog.setMessage("Progress start");
this.dialog.show();
}
@Override
protected List<String> doInBackground(Void... arg0) {
if (isOnline())
{
try{
Toast.makeText(getApplicationContext(), "Start",
Toast.LENGTH_LONG).show();
request = new HttpGet("www.com");
}catch(NullPointerException e ){
e.printStackTrace();}
jsonhandler handler = new jsonhandler();
try
{
return client.execute(request,handler);
}catch(ClientProtocolException exception){
exception.printStackTrace();
}catch(IOException exception){
exception.printStackTrace();
}
}
return null;
}
protected void onPostExecute(List<String> result)
{
super.onPostExecute(result);
if (this.client != null) {
this.client.close();
}
}
}
private class jsonhandler implements ResponseHandler<List<String>>{
@Override
public List<String> handleResponse(HttpResponse response)
throws ClientProtocolException, IOException {
//List<String> result = new ArrayList<String>();
String jsonresponse = new BasicResponseHandler().handleResponse(response);
int i;
JSONArray data;
try {
Toast.makeText(getApplicationContext(), "Json Enter",
Toast.LENGTH_LONG).show();
data = new JSONArray(jsonresponse);
for(i=0;i<data.length();i++)
{
JSONObject obj = (JSONObject)data.get(i);
name[i]=obj.get("name").toString();
org[i]=obj.get("organisation").toString();
desc[i]=obj.getString("description").toString();
date[i]=obj.get("date").toString();
time[i]=obj.get("timings").toString();
loc[i]=obj.get("location").toString();
cname1[i]=obj.get("cname1").toString();
pho1[i]=obj.get("cno1").toString();
cname2[i]=obj.get("cname2").toString();
pho2[i]=obj.get("cno2").toString();
email[i]=obj.get("email").toString();
team[i]=obj.get("team").toString();
tid[i]=Integer.parseInt(obj.get("tid").toString());
fee[i]=obj.get("fee").toString();
}
k=i;
}catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
}
错误是
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:300)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:200)
at android.os.Handler.<init>(Handler.java:114)
at android.widget.Toast$TN.<init>(Toast.java:327)
at android.widget.Toast.<init>(Toast.java:92)
at android.widget.Toast.makeText(Toast.java:241)
at com.example.gravitas2015.MainActivity$jsonhandler.handleResponse(MainActivity.java:269)
at com.example.gravitas2015.MainActivity$jsonhandler.handleResponse(MainActivity.java:1)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:657)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:627)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:616)
at android.net.http.AndroidHttpClient.execute(AndroidHttpClient.java:273)
at com.example.gravitas2015.MainActivity$request.doInBackground(MainActivity.java:240)
at com.example.gravitas2015.MainActivity$request.doInBackground(MainActivity.java:1)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
答案 0 :(得分：0)
您无法在后台线程中显示Toast消息。删除下面的代码，然后重试。
Toast.makeText(getApplicationContext(), "Json Enter",
Toast.LENGTH_LONG).show();