无法从Android的EditText字段获取输入

Question

我正在开发一个Android应用程序。我想在edittext字段中输入字符串作为输入。这里我想用这个字符串作为urlencoder。所以每次当我在文本字段中键入一些东西时，这个改变必须到达urlencoder。

public class MainActivity extends Activity { 

int converId=1; 
Button button1; 
EditText edittext; 
String ask, query;{ 
try { 

    ///I want to put user input value at query string as string 

query="hi"; 

    ///This query string encoded here 

ask=URLEncoder.encode(query, "UTF-8"); 
Log.d("TEST", ask); 
} catch (UnsupportedEncodingException e) { 
    e.printStackTrace(); 
} 
} 
TextView tv; 
String str_botsay; 

String fm = "&format=json&convo_id="; 
String fpart = "http://10.0.2.2/POM/chatbot/conversation_start.php?say=", 
url = fpart+ask+fm+converId; 

String URL = url.toString(); 
public static final String TAG_USERSAY = "usersay"; 
public static final String TAG_BOTSAY = "botsay"; 
public static final String TAG_CONVO_ID = "convo_id"; 

JSONParser jParser = new JSONParser(); 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    tv= (TextView) findViewById(R.id.tv); 
    edittext= (EditText) findViewById(R.id.editText1); 
    button1 = (Button) findViewById(R.id.button1); 
    query= edittext.getText().toString(); 
    button1.setOnClickListener(new View.OnClickListener() { 
    public void onClick(View arg0) { 

     //I place this line for that but i don't works 

    query= edittext.getText().toString(); 
    new GetBotResponse().execute(); 
    } 
    }); 

} 


private class GetBotResponse extends AsyncTask<Void, Void, Void>{ 


    @Override 
    protected Void doInBackground(Void... params) { 
     // TODO Auto-generated method stub 
     JSONObject json = jParser.getJSONFromUrlByGet(URL); 
     try { 

      String str_usersay = json.getString(TAG_USERSAY); 

      Log.i("TAG_usersay", str_usersay); 
      str_botsay = json.getString(TAG_BOTSAY); 

      Log.i("TAG_botsay", str_botsay); 
      String str_convo_id = json.getString(TAG_CONVO_ID); 

      Log.i("TAG_convo_id", str_convo_id); 
     } catch (JSONException e) { 
     } 
     return null; 
    } 

    @Override 
    protected void onPostExecute(Void result) { 
     // TODO Auto-generated method stub 
     tv.setText(str_botsay); 

    } 

} 
    } 

请帮我解决这个问题！

---

这是我的项目的日志

---

04-05 16:00:13.415: D/AndroidRuntime(339): Shutting down VM 
04-05 16:00:13.415: W/dalvikvm(339): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
04-05 16:00:13.515: E/AndroidRuntime(339): FATAL EXCEPTION: main 
04-05 16:00:13.515: E/AndroidRuntime(339): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.jsontest/com.example.jsontest.MainActivity}: java.lang.NullPointerException 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.os.Handler.dispatchMessage(Handler.java:99) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.os.Looper.loop(Looper.java:123) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread.main(ActivityThread.java:4627) 
04-05 16:00:13.515: E/AndroidRuntime(339): at java.lang.reflect.Method.invokeNative(Native Method) 
04-05 16:00:13.515: E/AndroidRuntime(339): at java.lang.reflect.Method.invoke(Method.java:521) 
04-05 16:00:13.515: E/AndroidRuntime(339): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
04-05 16:00:13.515: E/AndroidRuntime(339): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
04-05 16:00:13.515: E/AndroidRuntime(339): at dalvik.system.NativeStart.main(Native Method) 
04-05 16:00:13.515: E/AndroidRuntime(339): Caused by: java.lang.NullPointerException 
04-05 16:00:13.515: E/AndroidRuntime(339): at java.net.URLEncoder.encode(URLEncoder.java:94) 
04-05 16:00:13.515: E/AndroidRuntime(339): at com.example.jsontest.MainActivity.<init>(MainActivity.java:32) 
04-05 16:00:13.515: E/AndroidRuntime(339): at java.lang.Class.newInstanceImpl(Native Method) 
04-05 16:00:13.515: E/AndroidRuntime(339): at java.lang.Class.newInstance(Class.java:1429) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 
04-05 16:00:13.515: E/AndroidRuntime(339): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577) 
04-05 16:00:13.515: E/AndroidRuntime(339): ... 11 more 
04-05 16:05:13.608: I/Process(339): Sending signal. PID: 339 SIG: 9 

Answer 1

更改按钮点击执行类似下面

button1.setOnClickListener(new View.OnClickListener() { 
    public void onClick(View arg0) { 
    query= edittext.getText().toString(); 
    url = fpart+query+fm+converId; 
    new GetBotResponse().execute(url); 
    } 
    }); 

Channge您的AsyncTask像下面的代码

private class GetBotResponse extends AsyncTask<String, Void, JSONObject>{ 


@Override 
protected JSONObject doInBackground(String... params) { 
    // TODO Auto-generated method stub 
    JSONObject json = jParser.getJSONFromUrlByGet(params[0]); 

    return json; 
} 

@Override 
protected void onPostExecute(JSONObject json) { 
if(json!=null) 
{ 
    try { 

     String str_usersay = json.getString(TAG_USERSAY); 

     Log.i("TAG_usersay", str_usersay); 
     String str_botsay = json.getString(TAG_BOTSAY); 

     Log.i("TAG_botsay", str_botsay); 
     String str_convo_id = json.getString(TAG_CONVO_ID); 

     Log.i("TAG_convo_id", str_convo_id); 
    } catch (JSONException e) { 
    } 
    } 
    tv.setText(str_botsay); 

    } 

    }