Question

我正在尝试在Android 4.0设备上进行登录和注册。所以我不得不更新我的代码以使用Asynctask，我收到错误，不知道如何解决它们。任何帮助将不胜感激！

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_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.activity_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) {

            new RegisterTask().execute();
        }
    });

    // 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();
        }
    });
}

class RegisterTask extends AsyncTask<String, String, String> {
int success;
String email;
String password;
String name;

@Override
protected void onPreExecute() {
    super.onPreExecute();
    email = inputEmail.getText().toString();
    password = inputPassword.getText().toString();
    name = inputFullName.getText().toString();
}

@Override
protected String doInBackground(String... args) {
    UserFunctions userFunction = new UserFunctions();
    JSONObject json = userFunction.registerUser(name, email, password);

    Log.d("Create Response", json.toString());

    try {
        int success = json.getInt(KEY_SUCCESS);
        if (success == 1) {
            // DATABASE HANDLER
            // user successfully logged in
            // 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_user.getString(KEY_UID),
                    json_user.getString(KEY_CREATED_AT));

        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return null;
}

protected void onPostExecute(String file_url) {
if (success == 1) {
        Intent dashboard = new Intent(getApplicationContext(), LoginActivity.class);
        dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(dashboard);
        finish();
}else{
    //tvLError.setText("Incorrect username/password");

 }
}
}
}

我得到的错误日志......

12-02 20：45：23.140：E / JSON Parser（28208）：解析数据时出错org.json.JSONException：Value

<br of type java.lang.String cannot be converted to JSONObject
12-02 20:45:23.140: W/dalvikvm(28208): threadid=13: thread exiting with uncaught exception (group=0x415e62a0)
12-02 20:45:23.140: E/AndroidRuntime(28208): FATAL EXCEPTION: AsyncTask #1
12-02 20:45:23.140: E/AndroidRuntime(28208): java.lang.RuntimeException: An error occured while executing doInBackground()
12-02 20:45:23.140: E/AndroidRuntime(28208): at android.os.AsyncTask$3.done(AsyncTask.java:299)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-02 20:45:23.140: E/AndroidRuntime(28208): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.lang.Thread.run(Thread.java:856)
12-02 20:45:23.140: E/AndroidRuntime(28208): Caused by: java.lang.NullPointerException
12-02 20:45:23.140: E/AndroidRuntime(28208): at com.example.cs309.gotoclass.RegisterActivity$RegisterTask.doInBackground(RegisterActivity.java:89)
12-02 20:45:23.140: E/AndroidRuntime(28208): at com.example.cs309.gotoclass.RegisterActivity$RegisterTask.doInBackground(RegisterActivity.java:1)
12-02 20:45:23.140: E/AndroidRuntime(28208): at android.os.AsyncTask$2.call(AsyncTask.java:287)
12-02 20:45:23.140: E/AndroidRuntime(28208): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-02 20:45:23.140: E/AndroidRuntime(28208): ... 5 more

registerUser

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;
}

Answer 1

确保验证您的空值的登录详细信息＆amp;然后只调用AsychTask＆amp;调用registerUser（）方法。

Answer 2

如果没有prper源代码，很难搞清楚。但请检查RegisterActivity.java中的第89行，它是从doInBackground（）调用的。设置一个断点并检查哪个项目为NULL（因为你得到了NullPointerException）。一旦你解决了它就可以了。

使用JSON进行Android 4.0登录和注册

2 个答案: