Java android中带有json的NullPointerException错误
我知道StackOverFlow中有很多关于这个错误的解释。但我花了无数个小时试图解决代码中的这个错误，但我做不到。我是android编程新手。希望你们能帮忙 我试图在这个android应用程序中使用PHP将数据存储在MySQL中 这是我的主要活动Java android中带有json的NullPointerException错误,java,android,Java,Android,我知道StackOverFlow中有很多关于这个错误的解释。但我花了无数个小时试图解决代码中的这个错误，但我做不到。我是android编程新手。希望你们能帮忙 我试图在这个android应用程序中使用PHP将数据存储在MySQL中 这是我的主要活动 public class MainActivity extends ActionBarActivity implements View.OnClickListener { private EditText userName, userCon
public class MainActivity extends ActionBarActivity implements View.OnClickListener {
private EditText userName, userContact, userAddress, userRequest;
private Spinner userStore;
private Button mRegister;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
JSONParser jsonParser = new JSONParser();
//php login script
//localhost :
//testing on your device
//put your local ip instead, on windows, run CMD > ipconfig
//or in mac's terminal type ifconfig and look for the ip under en0 or en1
// private static final String LOGIN_URL = "http://xxx.xxx.x.x:1234/webservice/register.php";
//testing on Emulator:
private static final String LOGIN_URL = "http://10.0.2.2/callarocket/register.php";
//testing from a real server:
//private static final String LOGIN_URL = "http://www.yourdomain.com/webservice/register.php";
//ids
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Spinner dropdown = (Spinner)findViewById(R.id.StoreSpinner);
String[] items = new String[]{"NZ Mamak", "Indo Shop", "NZ Supermarket"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, items);
dropdown.setAdapter(adapter);
userName = (EditText)findViewById(R.id.EditName);
userContact = (EditText)findViewById(R.id.EditContact);
userAddress = (EditText)findViewById(R.id.EditAddress);
userStore = (Spinner)findViewById(R.id.StoreSpinner);
userRequest = (EditText)findViewById(R.id.EditRequest);
mRegister = (Button)findViewById(R.id.SubmitButton);
mRegister.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
new CreateUser().execute();
}
class CreateUser extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
boolean failure = false;
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Creating Request...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected String doInBackground(String... args) {
// TODO Auto-generated method stub
// Check for success tag
int success;
String username = userName.getText().toString();
String usercontact = userContact.getText().toString();
String useraddress = userAddress.getText().toString();
String userstore = userStore.getSelectedItem().toString();
String userrequest = userRequest.getText().toString();
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("userName", username));
params.add(new BasicNameValuePair("userContact", usercontact));
params.add(new BasicNameValuePair("userAddress", useraddress));
params.add(new BasicNameValuePair("userStore", userstore));
params.add(new BasicNameValuePair("userRequest", userrequest));
Log.d("request!", "starting");
//Posting user data to script
JSONObject json = jsonParser.makeHttpRequest(
LOGIN_URL, "POST", params);
// full json response
Log.d("Login attempt", json.toString());
// json success element
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Log.d("User Created!", json.toString());
finish();
return json.getString(TAG_MESSAGE);
}else{
Log.d("Login Failure!", json.getString(TAG_MESSAGE));
return json.getString(TAG_MESSAGE);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once product deleted
pDialog.dismiss();
if (file_url != null){
Toast.makeText(MainActivity.this, file_url, Toast.LENGTH_LONG).show();
}
}
}
}
公共类MainActivity扩展了ActionBarActivity实现了View.OnClickListener{
私有EditText用户名、userContact、userAddress、userRequest；
私有微调器用户存储；
私人按钮注册器；
//进度对话框
私人对话；
//JSON解析器类
JSONParser JSONParser=新的JSONParser（）；
//php登录脚本
//本地主机：
//在您的设备上进行测试
//将本地ip改为在windows上运行CMD>ipconfig
//或者在mac的终端类型ifconfig中，查找en0或en1下的ip
//私有静态最终字符串登录\u URL=”http://xxx.xxx.x.x:1234/webservice/register.php";
//在模拟器上测试：
私有静态最终字符串登录\u URL=”http://10.0.2.2/callarocket/register.php";
//从真实服务器进行测试：
//私有静态最终字符串登录\u URL=”http://www.yourdomain.com/webservice/register.php";
//身份证
私有静态最终字符串标记_SUCCESS=“SUCCESS”；
私有静态最终字符串标记_MESSAGE=“MESSAGE”；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
//TODO自动生成的方法存根
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
微调器下拉列表=（微调器）findViewById（R.id.StoreSpinner）；
字符串[]项=新字符串[]{“NZ Mamak”、“Indo Shop”、“NZ超市”}；
ArrayAdapter=新的ArrayAdapter（这个，android.R.layout.simple\u微调器\u项，项）；
下拉列表.setAdapter（适配器）；
用户名=（EditText）findViewById（R.id.EditName）；
userContact=（EditText）findViewById（R.id.EditContact）；
userAddress=（EditText）findViewById（R.id.EditAddress）；
userStore=（微调器）findviewbyd（R.id.StoreSpinner）；
userRequest=（EditText）findViewById（R.id.EditRequest）；
mRegister=（按钮）findviewbyd（R.id.SubmitButton）；
mRegister.setOnClickListener（此）；
}
@凌驾
公共void onClick（视图v）{
//TODO自动生成的方法存根
新建CreateUser（）.execute（）；
}
类CreateUser扩展异步任务{
/**
*在启动后台线程显示进度对话框之前
* */
布尔失败=假；
@凌驾
受保护的void onPreExecute（）{
super.onPreExecute（）；
pDialog=新建进度对话框（MainActivity.this）；
setMessage（“创建请求…”）；
pDialog.setUndeterminate（假）；
pDialog.setCancelable（真）；
pDialog.show（）；
}
@凌驾
受保护的字符串doInBackground（字符串…args）{
//TODO自动生成的方法存根
//检查成功标签
成功；
字符串username=username.getText（）.toString（）；
字符串usercontact=usercontact.getText（）.toString（）；
字符串useraddress=useraddress.getText（）.toString（）；
字符串userstore=userstore.getSelectedItem（）.toString（）；
字符串userrequest=userrequest.getText（）.toString（）；
试一试{
//建筑参数
List params=new ArrayList（）；
添加（新的BasicNameValuePair（“用户名”，用户名））；
添加（新的BasicNameValuePair（“userContact”，userContact））；
添加（新的BasicNameValuePair（“userAddress”，userAddress））；
添加（新的BasicNameValuePair（“userStore”，userStore））；
添加（新的BasicNameValuePair（“userRequest”，userRequest））；
Log.d（“请求！”，“启动”）；
//将用户数据发布到脚本
JSONObject json=jsonParser.makeHttpRequest(
登录URL，“POST”，参数）；
//完整json响应
Log.d（“登录尝试”，json.toString（））；
//json成功元素
success=json.getInt（TAG_success）；
如果（成功==1）{
Log.d（“用户创建的！”，json.toString（））；
完成（）；
返回json.getString（TAG_消息）；
}否则{
Log.d（“登录失败！”，json.getString（TAG_MESSAGE））；
返回json.getString（TAG_消息）；
}
}捕获（JSONException e）{
e、 printStackTrace（）；
}
返回null；
}
/**
*完成后台任务后，关闭“进度”对话框
* **/
受保护的void onPostExecute（字符串文件\u url）{
//删除产品后关闭对话框
pDialog.disclose（）；
如果（文件url！=null）{
Toast.makeText（MainActivity.this，file_url，Toast.LENGTH_LONG.show（）；
}
}
}
}
public class JSONParser {
static InputStream is = null ;
static JSONObject jObj = null ;
static String json = " " ;
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(final String url) {
// Making HTTP request
try {
// Construct the client and the HTTP request.
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
// Execute the POST request and store the response locally.
HttpResponse httpResponse = httpClient.execute(httpPost);
// Extract data from the response.
HttpEntity httpEntity = httpResponse.getEntity();
// Open an inputStream with the data content.
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
// Create a BufferedReader to parse through the inputStream.
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
// Declare a string builder to help with the parsing.
StringBuilder sb = new StringBuilder();
// Declare a string to store the JSON object data in string form.
String line = null;
// Build the string until null.
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
// Close the input stream.
is.close();
// Convert the string builder data to an actual string.
json = sb.toString();
//Log.i("DATA","json data is :: "+json);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// Try to parse the string to a JSON object
try {
jObj = new JSONObject(json);
//jarr = new JSONArray(json);
//jObj = jarr.getJSONObject(0);
//JSONParser parser = new JSONParser();
//Object obj = parser.parse(json);
//JSONObject jsonObj = (JSONObject) obj;
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// Return the JSON Object.
return jObj;
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
公共类JSONParser{
静态InputStream为空；
静态JSONObject jObj=null；
静态字符串json=“”；
//建造师
公共JSONParser（）{
}
公共JSONObject getJSONFromUrl（最终字符串url）{
//发出HTTP请求
试一试{
//构造客户端和HTTP请求。
DefaultHttpClient httpClient=新的DefaultHttpClient（）；
HttpPost HttpPost=新的HttpPost（url）；
//执行POST请求并在本地存储响应。
HttpResponse HttpResponse=httpClient.execute（httpPost）；
//从响应中提取数据。
HttpEntity HttpEntity=httpResponse.ge
02-25 14:13:43.070 2708-2725/com.example.user.callarocket D/request!﹕ starting
02-25 14:13:43.132 2708-2723/com.example.user.callarocket W/EGL_emulation﹕ eglSurfaceAttrib not implemented
02-25 14:13:43.132 2708-2723/com.example.user.callarocket W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa6c46c20, error=EGL_SUCCESS
02-25 14:13:43.318 2708-2725/com.example.user.callarocket E/JSON Parser﹕ Error parsing data org.json.JSONException: Value Posted of type java.lang.String cannot be converted to JSONObject
02-25 14:13:43.318 2708-2725/com.example.user.callarocket E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #2
Process: com.example.user.callarocket, PID: 2708
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:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.json.JSONObject.toString()' on a null object reference
at com.example.user.callarocket.MainActivity$CreateUser.doInBackground(MainActivity.java:129)
at com.example.user.callarocket.MainActivity$CreateUser.doInBackground(MainActivity.java:86)
at android.os.AsyncTask$2.call(AsyncTask.java:288)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$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:818)
02-25 14:13:45.643 2708-2708/com.example.user.callarocket E/WindowManager﹕ android.view.WindowLeaked: Activity com.example.user.callarocket.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{279ba229 V.E..... R......D 0,0-1026,348} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:363)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:261)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
at android.app.Dialog.show(Dialog.java:298)
at com.example.user.callarocket.MainActivity$CreateUser.onPreExecute(MainActivity.java:100)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
at android.os.AsyncTask.execute(AsyncTask.java:535)
at com.example.user.callarocket.MainActivity.onClick(MainActivity.java:82)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)