java - 按下登录按钮时强制关闭
问题描述
我有一个项目,当我运行它时,我按下登录按钮,我的应用程序总是强制关闭,但如果我再次启动我的应用程序,登录状态为 true。错误信息是:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at com.farid.starsrunway.login.LoginActivity$Masuk.onPostExecute(LoginActivity.java:126)
at com.farid.starsrunway.login.LoginActivity$Masuk.onPostExecute(LoginActivity.java:81)
at android.os.AsyncTask.finish(AsyncTask.java:667)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:684)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6157)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:891)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:781)
这是我的清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.farid.starsrunway">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".login.LoginActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".login.RegisterActivity"
android:label="Register New User">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".login.LoginActivity" />
<intent-filter>
<action android:name="android.intent.action.DETAIL" />
<category android:name="android.intent.category.DETAIL" />
</intent-filter>
</activity>
<activity
android:name=".MainmenuActivity"
android:label="Menu Utama">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".login.LoginActivity" />
<intent-filter>
<action android:name="android.intent.action.DETAIL" />
<category android:name="android.intent.category.DETAIL" />
</intent-filter>
</activity>
</application>
</manifest>
这是 SessionManager.java
package com.farid.starsrunway.login;
import java.util.HashMap;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
@SuppressLint("CommitPrefEdits")
public class SessionManager {
// Shared Preferences
private SharedPreferences pref;
// Editor for Shared preferences
private Editor editor;
// Context
private Context _context;
// nama sharepreference
private static final String PREF_NAME = "Sesi";
// All Shared Preferences Keys
private static final String IS_LOGIN = "IsLoggedIn";
//public static final String KEY_NAME = "nama";
private static final String KEY_USER = "username";
// Constructor
public SessionManager(Context context){
this._context = context;
int PRIVATE_MODE = 0;
pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
editor = pref.edit();
}
/**
* Create login session
* */
public void createLoginSession(String user, String username){
// Storing login value as TRUE
editor.putBoolean(IS_LOGIN, true);
//editor.putString(KEY_NAME, name);
editor.putString(KEY_USER, username);
editor.commit();
}
/**
* Check login method wil check user login status
* If false it will redirect user to login page
* Else won't do anything
* */
public void checkLogin(){
// Check login status
if(!this.isLoggedIn()){
Intent i = new Intent(_context, LoginActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
_context.startActivity(i);
//((Activity)_context).finish();
}
}
/**
* Get stored session data
* */
public HashMap<String, String> getUserDetails(){
HashMap<String, String> user = new HashMap<String, String>();
//user.put(KEY_NAME, pref.getString(KEY_NAME, null));
user.put(KEY_USER, pref.getString(KEY_USER, null));
return user;
}
/**
* Clear session details
* */
public void logoutUser(){
// Clearing all data from Shared Preferences
editor.clear();
editor.commit();
Intent i = new Intent(_context, LoginActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
_context.startActivity(i);
}
public boolean isLoggedIn(){
return pref.getBoolean(IS_LOGIN, false);
}
}
这是 LoginActivity.java
package com.farid.starsrunway.login;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import com.farid.starsrunway.Konfigurasi;
import com.farid.starsrunway.MainmenuActivity;
import com.farid.starsrunway.R;
import android.annotation.SuppressLint;
import android.content.Intent;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Objects;
import org.json.JSONArray;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.app.ProgressDialog;
import android.util.Log;
import com.farid.starsrunway.JSONParser;
public class LoginActivity extends AppCompatActivity implements View.OnClickListener {
EditText EditUser, EditPass;
Button ButtonLogin, ButtonDaftar, ButtonCancel;
String url, success;
SessionManager session;
String st = "1";
String benar = "benar";
@Override
protected void onCreate(Bundle savedInstanceState) {
success = null;
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
session = new SessionManager(getApplicationContext());
Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();
EditUser = findViewById(R.id.editUser);
EditPass = findViewById(R.id.editPass);
ButtonLogin = findViewById(R.id.buttonLogin);
ButtonCancel = findViewById(R.id.buttonCancel);
ButtonDaftar = findViewById(R.id.buttonDaftar);
ButtonLogin.setOnClickListener(this);
ButtonCancel.setOnClickListener(this);
ButtonDaftar.setOnClickListener(this);
}
public void login(){
String User = EditUser.getText().toString().trim();
String Pass = EditPass.getText().toString().trim();
url = Konfigurasi.URL_LOGIN + "username="
+ User + "&password="
+ Pass;
if (EditUser.getText().toString().trim().length() > 0 && EditPass.getText().toString().trim().length() > 0) {
new Masuk().execute();
} else {
Toast.makeText(getApplicationContext(), "Username/password masih kosong gan.!!", Toast.LENGTH_LONG).show();
}
}
public void Daftar(){
startActivity(new Intent(LoginActivity.this, RegisterActivity.class));
}
public void cancel(){
finish();
}
@SuppressLint("StaticFieldLeak")
public class Masuk extends AsyncTask<String, String, String> {
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(LoginActivity.this);
pDialog.setMessage("Tunggu Bentar ya...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected String doInBackground(String... arg0) {
JSONParser jParser = new JSONParser();
JSONObject json = jParser.getJSONFromUrl(url);
try {
success = json.getString("success");
Log.e("error", "nilai sukses=" + success);
JSONArray hasil = json.getJSONArray("login");
if (success.equals(benar)) {
for (int i = 0; i < hasil.length(); i++) {
JSONObject c = hasil.getJSONObject(i);
String user = c.getString("username").trim();
String pass = c.getString("password").trim();
session.createLoginSession(user, pass);
Log.e("ok", " ambil data");
}
} else {
Log.e("error", "tidak bisa ambil data 0");
}
} catch (Exception e) {
Log.e("error", "tidak bisa ambil data 1");
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
pDialog.dismiss();
if (success.equals(benar)) {
startActivity(new Intent(LoginActivity.this, MainmenuActivity.class));
} else {
Toast.makeText(getApplicationContext(), "Username/password salah..!!", Toast.LENGTH_LONG).show();
}
}
}
@Override
public void onClick(View v) {
if (v == ButtonLogin){
login();
}
if (v == ButtonCancel){
cancel();
}
if (v == ButtonDaftar){
Daftar();
}
}
}
这是 JSONParser.java
package com.farid.starsrunway;
import android.util.Log;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.SocketException;
import java.util.List;
public class JSONParser {
static InputStream is = null;
private static JSONObject jObj = null;
private static String json = "";
// constructor
public JSONParser() {
//timeout = new Values().gettimeout();
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
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).append("\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;
}
// 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 {
HttpParams httpParameters = new BasicHttpParams();
int timeout = 10000;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeout);
HttpConnectionParams.setSoTimeout(httpParameters, timeout);
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
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(httpParameters);
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 (SocketException ste) {
Log.e("Timeout Exception: ", ste.toString());
} catch (ConnectTimeoutException e) {
Log.e("Timeout Exception: ", e.toString());
} 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).append("\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;
}
}
这是 konfigurasi.java
package com.farid.starsrunway;
public class Konfigurasi {
//Dibawah ini merupakan Pengalamatan dimana Lokasi Skrip CRUD PHP disimpan
//Pada tutorial Kali ini, karena kita membuat localhost maka alamatnya tertuju ke IP komputer
//dimana File PHP tersebut berada
//PENTING! JANGAN LUPA GANTI IP SESUAI DENGAN IP KOMPUTER DIMANA DATA PHP BERADA
private static final String BASE_URL = "http://runway.ikc.co.id/android/";
public static final String URL_READ = BASE_URL + "visit/read.php";
public static final String URL_INSERT = BASE_URL + "visit/create.php";
public static final String URL_UPDATE = BASE_URL + "visit/update.php";
public static final String URL_DELETE = BASE_URL + "visit/delete.php?id=";
public static final String URL_LOGIN = BASE_URL + "login/login.php?";
public static final String URL_REGISTER = BASE_URL + "login/register.php";
//Dibawah ini merupakan Kunci yang akan digunakan untuk mengirim permintaan ke Skrip PHP
public static final String KEY_ID = "id";
public static final String KEY_TANGGAL = "tanggal";
public static final String KEY_JAM = "jam"; //alamat itu variabel untuk alamat
public static final String KEY_LOC = "lokasi"; //lati itu variabel untuk latitude
public static final String KEY_KD_TOKO = "kodetoko"; //longi itu variabel untuk longitude
public static final String KEY_STATUS = "status";
public static final String KEY_KD_ASM = "kodeasm";
public static final String KEY_TYPE = "type";
public static final String KEY_USER = "username";
public static final String KEY_PASS = "password";
//JSON Tags
public static final String TAG_SUCCESS = "success";
public static final String TAG_VISIT = "visit";
public static final String TAG_ID = "id";
public static final String TAG_TANGGAL = "tanggal";
public static final String TAG_JAM = "jam";
public static final String TAG_KD_TOKO = "kodetoko";
public static final String TAG_LOC = "lokasi";
public static final String TAG_STATUS = "status";
public static final String TAG_KD_ASM = "kodeasm";
}
这是 RequestHandler.java
package com.farid.starsrunway;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import javax.net.ssl.HttpsURLConnection;
public class RequestHandler {
//Metode Untuk mengirim httpPostRequest
//Metode ini mengambil 2 Argumen
//Metode Pertama adalah URL dari Skrip yang digunakan untuk mengirimkan permintaan
//Yang lainnya adalah HashMap dengan nilai pasangan nama yang berisi data yang akan dikirim dengan permintaan
public String sendPostRequest(String requestURL, HashMap<String, String> postDataParams) {
//Membuat URL
URL url;
//Objek StringBuilder untuk menyimpan pesan diambil dari server
StringBuilder sb = new StringBuilder();
try {
//Inisialisasi URL
url = new URL(requestURL);
//Membuat Koneksi HttpURLConnection
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
//Konfigurasi koneksi
conn.setReadTimeout(15000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);
//Membuat Keluaran Stream
OutputStream os = conn.getOutputStream();
//Menulis Parameter Untuk Permintaan
//Kita menggunakan metode getPostDataString yang didefinisikan di bawah ini
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(getPostDataString(postDataParams));
writer.flush();
writer.close();
os.close();
int responseCode = conn.getResponseCode();
if (responseCode == HttpsURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
sb = new StringBuilder();
String response;
//Reading server response
while ((response = br.readLine()) != null){
sb.append(response);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return sb.toString();
}
public String sendGetRequest(String requestURL){
StringBuilder sb =new StringBuilder();
try {
URL url = new URL(requestURL);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String s;
while((s=bufferedReader.readLine())!=null){
sb.append(s).append("\n");
}
}catch(Exception ignored){
}
return sb.toString();
}
public String sendGetRequestParam(String requestURL, String id){
StringBuilder sb =new StringBuilder();
try {
URL url = new URL(requestURL+id);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String s;
while((s=bufferedReader.readLine())!=null){
sb.append(s).append("\n");
}
}catch(Exception ignored){
}
return sb.toString();
}
private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
StringBuilder result = new StringBuilder();
boolean first = true;
for (Map.Entry<String, String> entry : params.entrySet()) {
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
}
return result.toString();
}
}
这是 gradle:app
apply plugin: 'com.android.application'
android {
compileSdkVersion 28
useLibrary 'org.apache.http.legacy'
defaultConfig {
applicationId "com.farid.starsrunway"
minSdkVersion 15
targetSdkVersion 28
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
implementation 'com.android.support.constraint:constraint-layout:1.1.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}
这是 login.php
<?php
include "koneksi.php";
$user = $_GET["username"];
$pas = $_GET["password"];
$pass = md5($pas);
$query = "SELECT * FROM User WHERE Username='$user' AND Password='$pass' ";
$hasil = mysqli_query($con, $query);
if (mysqli_num_rows($hasil) > 0) {
$response = array();
$response["login"] = array();
while ($data = mysqli_fetch_array($hasil)){
$login['Id'] = $data['Id'];
$login['Type'] = $data['Type'];
$login['Username'] = $data['Username'];
$login['Password'] = $data['Password'];
array_push($response["login"], $login);
}
$response["success"] = benar;
echo json_encode($response);
} else {
$response["success"] = salah;
$response["message"] = "Tidak ada data";
echo json_encode($response);
}
?>
你能帮我吗。我在 3 天前尝试解决此问题,但无法解决。
解决方案
这是因为在您的LoginActivity.java
第 124 行中,if (success.equals(benar))
会导致 NullPointerException。根据我从您的代码中可以理解的内容,如果您更改
success = null;
至
success = "notbenar"; //or basically any value that is not null
在第 39 行,您的问题应该得到解决。
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