Question

我正在使用以下代码在我的服务器上的sql数据库中注册用户。

package com.cc.envoycc.activity;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.cc.envoycc.R;
import com.cc.envoycc.app.AppConfig;
import com.cc.envoycc.app.AppController;
import com.cc.envoycc.helper.SQLiteHandler;
import com.cc.envoycc.helper.SessionManager;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by Harsh Ohri on 2/27/2016.
 */
public class RegisterActivity extends Activity {

    private static final String TAG = RegisterActivity.class.getSimpleName();
    private Button btnRegister;
    private Button btnLinkToLogin;
    private EditText inputFullName;
    private EditText inputEmail;
    private EditText inputPassword;
    private SQLiteHandler db;
    private SessionManager session;
    private ProgressDialog pDialog;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);

        btnRegister = (Button) findViewById(R.id.btnRegister);
        btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLogin);
        inputFullName = (EditText) findViewById(R.id.name);
        inputEmail = (EditText) findViewById(R.id.email);
        inputPassword = (EditText) findViewById(R.id.password);

        pDialog = new ProgressDialog(this);
        pDialog.setCancelable(false);

        session = new SessionManager(getApplicationContext());
        db = new SQLiteHandler(getApplicationContext());

        if (session.isLoggedIn()) {
            Intent intent = new Intent(RegisterActivity.this, MainActivity.class);
            startActivity(intent);
            finish();
        }

        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = inputFullName.getText().toString();
                String email = inputEmail.getText().toString();
                String password = inputPassword.getText().toString();

                if (!name.isEmpty() && !email.isEmpty() && !password.isEmpty()) {
                    registerUser(name, email, password);
                } else {
                    Toast.makeText(getApplicationContext(), "Please enter the credentials", Toast.LENGTH_LONG).show();
                }
            }
        });

        btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
                startActivity(intent);
                finish();
            }
        });
    }

    private void registerUser(final String name, final String email, final String password) {
        String tag_string_req = "req_register";
        pDialog.setMessage("Registering....");
        showDialog();

        StringRequest strReq = new StringRequest(Request.Method.POST, AppConfig.URL_REGISTER,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        Log.d(TAG, "Register response :" + response.toString());
                        hideDialog();
                        try {
                            JSONObject jObj = new JSONObject(response);
                            boolean error = jObj.getBoolean("error");
                            if (!error) {
                                String uid = jObj.getString("uid");
                                JSONObject user = jObj.getJSONObject("user");
                                String name = user.getString("user");
                                String email = user.getString("email");
                                String created_at = user.getString("created_at");

                                db.addUser(name, email, uid, created_at);

                                Toast.makeText(getApplicationContext(), "User successfully registered.PLease login now", Toast.LENGTH_LONG).show();

                                Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
                                startActivity(intent);
                                finish();

                            } else {
                                String errorMsg = jObj.getString("error_msg");
                                Toast.makeText(getApplicationContext(),
                                        errorMsg, Toast.LENGTH_LONG).show();
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e(TAG, "Response error:" + error.getMessage());
                Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
                hideDialog();
            }
        }) {
            @Override
            protected Map<String, String> getParams() {
                Map<String, String> params = new HashMap<String, String>();
                params.put("name", name);
                params.put("email", email);
                params.put("password", password);
                return params;
            }
        };
        AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
    }

    private void showDialog() {
        if (!pDialog.isShowing())
            pDialog.show();
    }

    private void hideDialog() {
        if (pDialog.isShowing())
            pDialog.dismiss();
    }
}'

点击注册按钮后我得到空指针异常请帮忙我是第一次使用排球图书馆

这里是logcat

`

java.lang.NullPointerException                                                                  at com.android.volley.Request.<init>(Request.java:136)                                                                  at com.android.volley.toolbox.StringRequest.<init>(StringRequest.java:43)                                                                  at com.cc.envoycc.activity.RegisterActivity$5.<init>(RegisterActivity.java:137)                                                                  at com.cc.envoycc.activity.RegisterActivity.registerUser(RegisterActivity.java:97)
at com.cc.envoycc.activity.RegisterActivity.access$300(RegisterActivity.java:32)
at com.cc.envoycc.activity.RegisterActivity$1.onClick(RegisterActivity.java:75)
at android.view.View.performClick(View.java:4191)
at android.view.View$PerformClick.run(View.java:17229)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4960)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
at dalvik.system.NativeStart.main(Native Method)

`

Answer 1

在寄存器按钮的if条件中检查是否为空。名称，电子邮件或密码均为空

 btnRegister.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String name = inputFullName.getText().toString();
            String email = inputEmail.getText().toString();
            String password = inputPassword.getText().toString();

            //Check for null here. Either name, email or password is null
            if (!name.isEmpty() && !email.isEmpty() && !password.isEmpty()) {
                registerUser(name, email, password);
            } else {
                Toast.makeText(getApplicationContext(), "Please enter the credentials", Toast.LENGTH_LONG).show();
            }
        }
    });

Volley库中StringRequest中的NullPointer异常

1 个答案: