httppost 代码编写问题...

[猫太大]

求各位大神给看看

Activity
private Button mButton1,mButton2; 
private TextView mTextView1; 
private JoyHttp j;
@Override 
  public void onCreate(Bundle savedInstanceState) 
  { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
     
    /*透过findViewById建构子建立TextView与Button对象*/ 
    mButton1 =(Button) findViewById(R.id.myButton1); 
    mButton2 =(Button) findViewById(R.id.myButton2);
    mTextView1 = (TextView) findViewById(R.id.myTextView1); 
     
    /*设定OnClickListener来聆听OnClick事件*/
    mButton1.setOnClickListener(new Button.OnClickListener() 
    { 
      /*重写onClick事件*/
      @Override 
      public void onClick(View v) 
      { 
        /*声明网址字符串*/
        String uriAPI = "http://localhost:8080";
        String message = "123";
//        post(uriAPI);
        mTextView1.setText(j.post(uriAPI,message)); 
  
      } 
    }); 

Post
public String post(String uriAPI, String message)
  {
    String fal = "fal";
    HttpPost httpRequest = new HttpPost(uriAPI);

    try
    {
      /* 发出HTTP request */ 
      httpRequest.setEntity(new StringEntity(message));
      // httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
      /* 取得HTTP response */
      HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
      /* 若状态码为200 ok */
      if (httpResponse.getStatusLine().getStatusCode() == 200)
      {
        /* 取出响应字符串 */
        String strResult = EntityUtils.toString(httpResponse.getEntity());
        // mTextView1.setText(strResult); 
        return strResult;
      }
      // else 
      // { 
      // mTextView1.setText("Error Response: "+httpResponse.getStatusLine().toString());
      // }
    } catch (ClientProtocolException e)
    {
      e.printStackTrace();
    } catch (IOException e)
    {
      e.printStackTrace();
    } catch (Exception e)
    {
      e.printStackTrace();
    }

    return fal;
  }

log
09-24 15:39:47.529: E/AndroidRuntime(14810): FATAL EXCEPTION: main
09-24 15:39:47.529: E/AndroidRuntime(14810): java.lang.RuntimeException: Unable to start activity ComponentInfo{irdc.EX08_01/irdc.EX08_01.EX08_01}: java.lang.NullPointerException
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread.access$600(ActivityThread.java:127)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.os.Handler.dispatchMessage(Handler.java:99)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.os.Looper.loop(Looper.java:137)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread.main(ActivityThread.java:4511)
09-24 15:39:47.529: E/AndroidRuntime(14810): at java.lang.reflect.Method.invokeNative(Native Method)
09-24 15:39:47.529: E/AndroidRuntime(14810): at java.lang.reflect.Method.invoke(Method.java:511)
09-24 15:39:47.529: E/AndroidRuntime(14810): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:980)
09-24 15:39:47.529: E/AndroidRuntime(14810): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747)
09-24 15:39:47.529: E/AndroidRuntime(14810): at dalvik.system.NativeStart.main(Native Method)
09-24 15:39:47.529: E/AndroidRuntime(14810): Caused by: java.lang.NullPointerException
09-24 15:39:47.529: E/AndroidRuntime(14810): at irdc.EX08_01.EX08_01.onCreate(EX08_01.java:50)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.Activity.performCreate(Activity.java:4470)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052)
09-24 15:39:47.529: E/AndroidRuntime(14810): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
09-24 15:39:47.529: E/AndroidRuntime(14810): ... 11 more
这该怎么改..

[veardn]

第50行空指针

[我是一个小胖子]

at irdc.EX08_01.EX08_01.onCreate(EX08_01.java:50)
没有初始化吧

[今夜不谈风月]

空指针这种错误，你把那一行找出来啊。