android php mysql org.json.JSONException:java.lang.String类型的值

我是android应用程序的新手。。我试着制作这个示例应用程序。。但每次我运行应用程序时，它总是说

错误org.json.JSONException:无法将java.lang.String类型的值br转换为JSONObject

。。在我的日志中。。我希望你能帮我做这件事

我的php文件

include("connection.php");
$mysqli->query("SET NAMES 'utf8'");
$project_id=$_REQUEST['project_id'];
$sql="SELECT project_id, project_name FROM project where project_id='$project_id'";
$result=$mysqli->query($sql);
while($e=mysqli_fetch_array($result)){
    $flag[project_name]=$e[project_name];
}
print(json_encode($flag));
$mysqli->close();

我的活动

公共类MainActivity扩展了活动{

String project_id;
String project_name;
InputStream is=null;
String result=null;
String line=null;

@Override    
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final EditText e_id=(EditText) findViewById(R.id.editText1);
    Button select=(Button) findViewById(R.id.button1);
    select.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            project_id=e_id.getText().toString();
            select();
        }
    });
}
public void select(){       
    ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("project_id",project_id));

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);

    try{

        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://10.0.2.2/select1.php");
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse response = httpclient.execute(httppost); 
        HttpEntity entity = response.getEntity();
        is = entity.getContent();   
        Log.e("pass 1", "connection success ");
    }

    catch(Exception e){

        Log.e("Fail 1", e.toString());
        Toast.makeText(getApplicationContext(), "Invalid IP Address",
        Toast.LENGTH_LONG).show();
    }     


    try{

        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"UTF-8"),8);        
        StringBuilder sb = new StringBuilder();
        while ((line = reader.readLine()) != null){     
            sb.append(line + "\n");
        }
        is.close();
        result = sb.toString();    
        Log.e("pass 2", "connection success ");
    }

    catch(Exception e){
        Log.e("Fail 2", e.toString());
    }     

    Log.i("tagconvertstr", "["+result+"]");
    try{   
        JSONObject json_data = new JSONObject(result);
        project_name = (json_data.getString("project_name"));
    }
    catch(Exception e){
        Log.e("Fail 3", e.toString());
    }    
}

---

}

请发布您的日志。我认为您没有获得JSON格式的输出。可能是服务器错误或其他原因，请检查它。log cat。。is org.json.JSONException:Value在转换为JSONObject之前，您是否记录了php的输出？发布您从服务器获得的json字符串