显示java.lang.NullPointerException:机器人产生的原因 [英] Android Caused by: java.lang.NullPointerException
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问题描述
我编辑现在...我检查的布局和初始化,但仍然是相同的error..is它也许月食错误?
公共类ActivityOwner扩展活动实现OnClickListener {
的EditText ownerUser,ownerPass;
私人按钮btnLogin;
私人ProgressDialog pDialog;
JSONParser jsonParser =新JSONParser();
私有静态最后弦乐OWNER_LOGIN_URL =http://192.168.2.5/idot/owner_login.php;
// --- JSON元素的PHP脚本的响应IDS
私有静态最后弦乐TAG_SUCCESS =成功;
私有静态最后弦乐TAG_MESSAGE =消息;
@覆盖
保护无效的onCreate(包savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.activity_owner);
ownerUser =(EditText上)findViewById(R.id.owner_login_username);
ownerPass =(EditText上)findViewById(R.id.owner_login_password);
TextView的tvLinkToRegister =(TextView中)findViewById(R.id.link_to_register);
tvLinkToRegister.setOnClickListener(新View.OnClickListener(){
@覆盖
公共无效的onClick(视图查看){
// TODO自动生成方法存根
意图registrationForm =新的意图(ActivityOwner.this,
ActivityOwnerRegister.class);
startActivity(registrationForm);
}
});
btnLogin =(按钮)findViewById(R.id.btnOwnerLogin);
btnLogin.setOnClickListener(本);
}
@覆盖
公共无效的onClick(视图v){
新AttemptLogin()执行()。
}
类AttemptLogin扩展的AsyncTask<字符串,字符串,字符串> {
@覆盖
在preExecute保护无效(){
super.on preExecute();
pDialog =新ProgressDialog(ActivityOwner.this);
pDialog.setMessage(试图登录......);
pDialog.setIndeterminate(假);
pDialog.setCancelable(真正的);
pDialog.show();
}
@覆盖
保护字符串doInBackground(字符串参数... args){
//检查成功标签
诠释成功;
字符串username = ownerUser.getText()的toString()。
。字符串password = ownerPass.getText()的toString();
尝试 {
//大厦参数
名单<的NameValuePair> PARAMS =新的ArrayList<的NameValuePair>();
params.add(新BasicNameValuePair(owner_username,用户名));
params.add(新BasicNameValuePair(owner_password,密码));
Log.d(!要求,出发);
//获取产品的详细信息通过HTTP请求
JSONObject的JSON = jsonParser.makeHtt prequest(OWNER_LOGIN_URL,
POST,则params);
//检查你的日志,JSON响应
Log.d(登录尝试,json.toString());
// json的成功标签
成功= json.getInt(TAG_SUCCESS);
如果(成功== 1){
Log.d(登录成功!,json.toString());
//保存用户数据
共享preferences SP = preferenceManager
.getDefaultShared preferences(ActivityOwner.this);
编辑器编辑= sp.edit();
edit.putString(owner_username,用户名);
edit.commit();
意图I =新的意图(ActivityOwner.this,
ActivityOwnerSuccessLogin.class);
pDialog.dismiss();
完();
startActivity(ⅰ);
返回json.getString(TAG_MESSAGE);
} 其他 {
Log.d(登录失败!,json.getString(TAG_MESSAGE));
返回json.getString(TAG_MESSAGE);
}
}赶上(JSONException E){
e.printStackTrace();
}
返回null;
}
@覆盖
保护无效onPostExecute(字符串结果){
//关闭该对话框,一旦产品中删除
pDialog.dismiss();
如果(结果!= NULL){
Toast.makeText(ActivityOwner.this,结果,Toast.LENGTH_SHORT)
。显示();
}
}
}
}
------ logcat的-------
11-14 21:30:52.517:E / AndroidRuntime(18929):由:显示java.lang.NullPointerException
11-14 21:30:52.517:E / AndroidRuntime(18929):在ph.idot.owner.ActivityOwner $ AttemptLogin.doInBackground(ActivityOwner.java:88)
解决方案
在一行的形式ABC的空指针异常是指东西点的左侧为空。在这个例子中:
- 在任一A为null;
- 或A·B为空。
不能有任何其他原因。因此,作为textView.getText()永远不会返回null,唯一的可能性就是用户
为空。
I Edited it now...I'm check the layout and the initialization but still the same error..is it maybe eclipse error?
public class ActivityOwner extends Activity implements OnClickListener {
EditText ownerUser, ownerPass;
private Button btnLogin;
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
private static final String OWNER_LOGIN_URL = "http://192.168.2.5/idot/owner_login.php";
// ---JSON element ids from response of php script
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_owner);
ownerUser = (EditText) findViewById(R.id.owner_login_username);
ownerPass = (EditText) findViewById(R.id.owner_login_password);
TextView tvLinkToRegister = (TextView) findViewById(R.id.link_to_register);
tvLinkToRegister.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// TODO Auto-generated method stub
Intent registrationForm = new Intent(ActivityOwner.this,
ActivityOwnerRegister.class);
startActivity(registrationForm);
}
});
btnLogin = (Button) findViewById(R.id.btnOwnerLogin);
btnLogin.setOnClickListener(this);
}
@Override
public void onClick(View v) {
new AttemptLogin().execute();
}
class AttemptLogin extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ActivityOwner.this);
pDialog.setMessage("Attempting login...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected String doInBackground(String... args) {
// Check for success tag
int success;
String username = ownerUser.getText().toString();
String password = ownerPass.getText().toString();
try {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("owner_username", username));
params.add(new BasicNameValuePair("owner_password", password));
Log.d("request!", "starting");
// getting product details by making HTTP request
JSONObject json = jsonParser.makeHttpRequest(OWNER_LOGIN_URL,
"POST", params);
// check your log for json response
Log.d("Login attempt", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Log.d("Login Successful!", json.toString());
// save user data
SharedPreferences sp = PreferenceManager
.getDefaultSharedPreferences(ActivityOwner.this);
Editor edit = sp.edit();
edit.putString("owner_username", username);
edit.commit();
Intent i = new Intent(ActivityOwner.this,
ActivityOwnerSuccessLogin.class);
pDialog.dismiss();
finish();
startActivity(i);
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;
}
@Override
protected void onPostExecute(String result) {
// dismiss the dialog once product deleted
pDialog.dismiss();
if (result != null) {
Toast.makeText(ActivityOwner.this, result, Toast.LENGTH_SHORT)
.show();
}
}
}
}
------LOGCAT-------
11-14 21:30:52.517: E/AndroidRuntime(18929): Caused by: java.lang.NullPointerException
11-14 21:30:52.517: E/AndroidRuntime(18929): at ph.idot.owner.ActivityOwner$AttemptLogin.doInBackground(ActivityOwner.java:88)
解决方案
A null pointer exception on a line of the form A.B.C means that something on the left-hand side of a dot is null. In this example :
- either A is null;
- or A.B is null.
There can be no other reason. So, as textView.getText() never returns null, the only possibility is that user
is null.
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