Json 由于致命异常,应用程序在emulator中意外停止
我已经获得了android应用程序的登录和注册屏幕,以及点击注册或登录按钮时与之相关的活动。保存时我没有收到任何错误。 但当我运行它时,屏幕会加载到emulator中,允许我输入数据,但只要我单击Register按钮或Login按钮,就会出现错误“应用程序意外停止,请重试” 以下是我在LogCat中得到的错误:Json 由于致命异常,应用程序在emulator中意外停止,json,android-emulator,nullpointerexception,Json,Android Emulator,Nullpointerexception,我已经获得了android应用程序的登录和注册屏幕,以及点击注册或登录按钮时与之相关的活动。保存时我没有收到任何错误。 但当我运行它时,屏幕会加载到emulator中,允许我输入数据,但只要我单击Register按钮或Login按钮,就会出现错误“应用程序意外停止,请重试” 以下是我在LogCat中得到的错误: 03-01 13:01:49.649: W/dalvikvm(583): threadid=1: thread exiting with uncaught exception (grou
03-01 13:01:49.649: W/dalvikvm(583): threadid=1: thread exiting with uncaught exception (group=0x40015560)
03-01 13:01:49.669: E/AndroidRuntime(583): FATAL EXCEPTION: main
03-01 13:01:49.669: E/AndroidRuntime(583): java.lang.NullPointerException
03-01 13:01:49.669: E/AndroidRuntime(583): at com.example.attendance2.RegisterActivity$1.onClick(RegisterActivity.java:59)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.view.View.performClick(View.java:2485)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.view.View$PerformClick.run(View.java:9080)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Handler.handleCallback(Handler.java:587)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Handler.dispatchMessage(Handler.java:92)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Looper.loop(Looper.java:123)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.app.ActivityThread.main(ActivityThread.java:3683)
03-01 13:01:49.669: E/AndroidRuntime(583): at java.lang.reflect.Method.invokeNative(Native Method)
03-01 13:01:49.669: E/AndroidRuntime(583): at java.lang.reflect.Method.invoke(Method.java:507)
03-01 13:01:49.669: E/AndroidRuntime(583): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-01 13:01:49.669: E/AndroidRuntime(583): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-01 13:01:49.669: E/AndroidRuntime(583): at dalvik.system.NativeStart.main(Native Method)
03-01 13:01:56.080: I/Process(583): Sending signal. PID: 583 SIG: 9
我已经检查了RegisterActivity.java,它看起来都很好。。。
我还添加了RegisterActivity.java和UserFunctions.java
请让我知道,如果你发现什么问题是,如果更多的编码是必需的!
当我尝试登录LoginActivity.java时,也会发生同样的错误
RegisterActivity.java
package com.example.attendance2;
import org.json.JSONException;
import org.json.JSONObject;
import library.DatabaseHandler;
import library.UserFunctions;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class RegisterActivity extends Activity {
Button btnRegister;
Button btnLinkToLogin;
EditText inputFullName;
EditText inputEmail;
EditText inputPassword;
TextView registerErrorMsg;
// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.register);
// Importing all assets like buttons, text fields
inputFullName = (EditText) findViewById(R.id.registerName);
inputEmail = (EditText) findViewById(R.id.registerEmail);
inputPassword = (EditText) findViewById(R.id.registerPassword);
btnRegister = (Button) findViewById(R.id.btnRegister);
btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
registerErrorMsg = (TextView) findViewById(R.id.register_error);
// Register Button Click event
btnRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String name = inputFullName.getText().toString();
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
UserFunctions userFunction = new UserFunctions();
JSONObject json = userFunction.registerUser(name, email, password);
// check for login response
try {
if (json.getString(KEY_SUCCESS) != null) {
registerErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
// user successfully registered
// Store user details in SQLite Database
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
// Clear all previous data in database
userFunction.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));
// Launch Dashboard Screen
Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
// Close all views before launching Dashboard
dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(dashboard);
// Close Registration Screen
finish();
}else{
// Error in registration
registerErrorMsg.setText("Error occured in registration");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
// Link to Login Screen
btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
LoginActivity.class);
startActivity(i);
// Close Registration View
finish();
}
});
}
}
UserFunctions.java
package library;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.jsn.JSONObject;
import android.content.Context;
public class UserFunctions {
private JSONParser jsonParser;
// Testing in localhost using wamp or xampp
// use http://10.0.2.2/ to connect to your localhost ie http://localhost/
private static String loginURL = "http://10.0.2.2:82/android_api/";
private static String registerURL = "http://10.0.2.2:82/android_api/";
private static String login_tag = "login";
private static String register_tag = "register";
// constructor
public UserFunctions(){
jsonParser = new JSONParser();
}
/**
* function make Login Request
* @param email
* @param password
* */
public JSONObject loginUser(String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", login_tag));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
// return json
// Log.e("JSON", json.toString());
return json;
}
/**
* function make Login Request
* @param name
* @param email
* @param password
* */
public JSONObject registerUser(String name, String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", register_tag));
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
// getting JSON Object
JSONObject json = jsonParser.getJSONFromUrl(registerURL, params);
// return json
return json;
}
/**
* Function get Login status
* */
public boolean isUserLoggedIn(Context context){
DatabaseHandler db = new DatabaseHandler(context);
int count = db.getRowCount();
if(count > 0){
// user logged in
return true;
}
return false;
}
/**
* Function to logout user
* Reset Database
* */
public boolean logoutUser(Context context){
DatabaseHandler db = new DatabaseHandler(context);
db.resetTables();
return true;
}
}
包库;
导入java.util.ArrayList;
导入java.util.List;
导入org.apache.http.NameValuePair;
导入org.apache.http.message.BasicNameValuePair;
导入org.jsn.JSONObject;
导入android.content.Context;
公共类用户函数{
私有JSONParser JSONParser;
//使用wamp或xampp在本地主机中进行测试
//使用http://10.0.2.2/ 要连接到本地主机,请执行以下操作:http://localhost/
专用静态字符串loginURL=”http://10.0.2.2:82/android_api/";
专用静态字符串注册表URL=”http://10.0.2.2:82/android_api/";
私有静态字符串login_tag=“login”;
专用静态字符串寄存器\u tag=“寄存器”;
//建造师
公共用户函数(){
jsonParser=新的jsonParser();
}
/**
*函数发出登录请求
*@param电子邮件
*@param密码
* */
公共JSONObject登录用户(字符串电子邮件、字符串密码){
//建筑参数
List params=new ArrayList();
添加(新的BasicNameValuePair(“标签”,登录标签));
参数添加(新的BasicNameValuePair(“电子邮件”),电子邮件);
添加(新的BasicNameValuePair(“密码”,password));
JSONObject json=jsonParser.getJSONFromUrl(loginURL,params);
//返回json
//Log.e(“JSON”,JSON.toString());
返回json;
}
/**
*函数发出登录请求
*@param name
*@param电子邮件
*@param密码
* */
公共JSONObject注册表服务器(字符串名称、字符串电子邮件、字符串密码){
//建筑参数
List params=new ArrayList();
参数添加(新的BasicNameValuePair(“标记”,寄存器_标记));
参数添加(新的BasicNameValuePair(“名称”),名称);
参数添加(新的BasicNameValuePair(“电子邮件”),电子邮件);
添加(新的BasicNameValuePair(“密码”,password));
//获取JSON对象
JSONObject json=jsonParser.getJSONFromUrl(registerURL,params);
//返回json
返回json;
}
/**
*函数获取登录状态
* */
公共布尔值isUserLoggedIn(上下文){
DatabaseHandler db=新的DatabaseHandler(上下文);
int count=db.getRowCount();
如果(计数>0){
//用户登录
返回true;
}
返回false;
}
/**
*用于注销用户的函数
*重置数据库
* */
公共布尔logoutUser(上下文){
DatabaseHandler db=新的DatabaseHandler(上下文);
db.resetTables();
返回true;
}
}
在我看来,registerErrorMsg是空的-例如,在布局中找不到您的文本视图。您使用的id(R.id.register\u error)可能在另一个元素中声明。谢谢您的回复。问题是json=null。但现在没事了。