Невозможно запустить Activity ComponentInfo {com.android.loginapp/com.android.loginapp.login}

Question

Эта ошибка заставляет мое приложение останавливаться каждый раз, когда я его запускаю, и не могу понять, почему. Думайте, что это может быть проблемой в файле XML, но не может его увидеть.

Это говорит Unfortunately login app has stopped working

Вот код:

login.java

public class login extends Activity { 

public static final String MY_PREFS = "SharedPreferences"; 
private DatabaseAdapter dbHelper; 
private EditText theUsername; 
private EditText thePassword; 
private Button loginButton; 
private Button registerButton; 
private Button clearButton; 
private Button exitButton; 
private CheckBox rememberDetails; 



@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    SharedPreferences mySharedPreferences = getSharedPreferences(MY_PREFS, 0); 
    Editor editor = mySharedPreferences.edit(); 
    editor.putLong("uid", 0); 
    editor.commit(); 

    dbHelper = new DatabaseAdapter(this); 
    dbHelper.open(); 

    setContentView(R.layout.main); 
    initControls(); 
} 

private void initControls() { 
    //Set the activity layout. 
    theUsername = (EditText) findViewById(R.id.Username); 
    thePassword = (EditText) findViewById(R.id.Password); 
    loginButton = (Button) findViewById(R.id.Login); 
    registerButton = (Button) findViewById(R.id.Register); 
    //clearButton = (Button) findViewById(R.id.Clear); 
    //exitButton = (Button) findViewById(R.id.Exit); 
    rememberDetails = (CheckBox) findViewById(R.id.RememberMe); 

    //Create touch listeners for all buttons. 
    loginButton.setOnClickListener(new Button.OnClickListener(){ 
     public void onClick (View v){ 
      LogMeIn(v); 
     } 
    }); 

    registerButton.setOnClickListener(new Button.OnClickListener(){ 
     public void onClick (View v){ 
      Register(v); 
     } 
    }); 

    clearButton.setOnClickListener(new Button.OnClickListener(){ 
     public void onClick (View v){ 
      ClearForm(); 
     } 
    }); 

    exitButton.setOnClickListener(new Button.OnClickListener(){ 
     public void onClick (View v){ 
      Exit(); 
     } 
    }); 
    //Create remember password check box listener. 
    rememberDetails.setOnClickListener(new CheckBox.OnClickListener(){ 
     public void onClick (View v){ 
      RememberMe(); 
     } 
    }); 

    //Handle remember password preferences. 
    SharedPreferences prefs = getSharedPreferences(MY_PREFS, 0); 
    String thisUsername = prefs.getString("username", ""); 
    String thisPassword = prefs.getString("password", ""); 
    boolean thisRemember = prefs.getBoolean("remember", false); 
    if(thisRemember) { 
     theUsername.setText(thisUsername); 
     thePassword.setText(thisPassword); 
     rememberDetails.setChecked(thisRemember); 
    } 

} 

/** 
* Deals with Exit option - exits the application. 
*/ 
private void Exit() 
{ 
    finish(); 
} 

/** 
* Clears the login form. 
*/ 
private void ClearForm() { 
    saveLoggedInUId(0,"",""); 
    theUsername.setText(""); 
    thePassword.setText(""); 
} 

/** 
* Handles the remember password option. 
*/ 
private void RememberMe() { 
    boolean thisRemember = rememberDetails.isChecked(); 
    SharedPreferences prefs = getSharedPreferences(MY_PREFS, 0); 
    Editor editor = prefs.edit(); 
    editor.putBoolean("remember", thisRemember); 
    editor.commit(); 
} 

/** 
* This method handles the user login process. 
* @param v 
*/ 
private void LogMeIn(View v) { 
    //Get the username and password 
    String thisUsername = theUsername.getText().toString(); 
    String thisPassword = thePassword.getText().toString(); 

    //Assign the hash to the password 
    thisPassword = md5(thisPassword); 

    // Check the existing user name and password database 
    Cursor theUser = dbHelper.fetchUser(thisUsername, thisPassword); 
    if (theUser != null) { 
     startManagingCursor(theUser); 
     if (theUser.getCount() > 0) { 
      saveLoggedInUId(theUser.getLong(theUser.getColumnIndex(DatabaseAdapter.COL_ID)), thisUsername, thePassword.getText().toString()); 
      stopManagingCursor(theUser); 
      theUser.close(); 
      Intent i = new Intent(v.getContext(), Helloworld.class); 
      startActivity(i); 
     } 

     //Returns appropriate message if no match is made 
     else { 
      Toast.makeText(getApplicationContext(), 
        "You have entered an incorrect username or password.", 
        Toast.LENGTH_SHORT).show(); 
      saveLoggedInUId(0, "", ""); 
     } 
     stopManagingCursor(theUser); 
     theUser.close(); 
    } 

    else { 
     Toast.makeText(getApplicationContext(), 
       "Database query error", 
       Toast.LENGTH_SHORT).show(); 
    } 
} 

/** 
* Open the Registration activity. 
* @param v 
*/ 
private void Register(View v) 
{ 
    Intent i = new Intent(v.getContext(), Register.class); 
    startActivity(i); 
} 

private void saveLoggedInUId(long id, String username, String password) { 
    SharedPreferences settings = getSharedPreferences(MY_PREFS, 0); 
    Editor myEditor = settings.edit(); 
    myEditor.putLong("uid", id); 
    myEditor.putString("username", username); 
    myEditor.putString("password", password); 
    boolean rememberThis = rememberDetails.isChecked(); 
    myEditor.putBoolean("rememberThis", rememberThis); 
    myEditor.commit(); 
} 

/** 
* Deals with the password encryption. 
* @param s The password. 
* @return 
*/ 
private String md5(String s) { 
    try { 
     MessageDigest digest = java.security.MessageDigest.getInstance("MD5"); 
     digest.update(s.getBytes()); 
     byte messageDigest[] = digest.digest(); 

     StringBuffer hexString = new StringBuffer(); 
     for (int i=0; i<messageDigest.length; i++) 
      hexString.append(Integer.toHexString(0xFF & messageDigest[i])); 

     return hexString.toString(); 
    } 

    catch (NoSuchAlgorithmException e) { 
     return s; 
    } 
} 
} 

main.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:background="#E6E6E6" > 

<TextView 
    android:id="@+id/Title" 
    android:layout_width="fill_parent" 
    android:layout_height="45dp" 
    android:background="#46C1EF" 
    android:gravity="center|fill_vertical" 
    android:text="MemRar" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:textColor="#ffffff" /> 

<TextView 
    android:id="@+id/lblLogin" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_marginLeft="51dp" 
    android:layout_marginTop="71dp" 
    android:text="Login:" 
    android:textAppearance="?android:attr/textAppearanceLarge" 
    android:textColor="#223355" /> 

<EditText 
    android:id="@+id/Username" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/lblLogin" 
    android:layout_below="@+id/lblLogin" 
    android:layout_marginTop="23dp" 
    android:ems="10" 
    android:gravity="fill_horizontal" 
    android:hint="Username" 
    android:inputType="textPersonName" 
    android:lines="1" 
    android:selectAllOnFocus="true" /> 

<EditText 
    android:id="@+id/Password" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/Username" 
    android:layout_alignRight="@+id/Username" 
    android:layout_below="@+id/Username" 
    android:layout_marginTop="28dp" 
    android:ems="10" 
    android:hint="Password" 
    android:inputType="textPassword" 
    android:lines="1" 
    android:selectAllOnFocus="true" /> 

<Button 
    android:id="@+id/Login" 
    android:layout_width="150dp" 
    android:layout_height="40dp" 
    android:layout_below="@+id/RememberMe" 
    android:layout_centerHorizontal="true" 
    android:layout_marginTop="15dp" 
    android:background="#46C1EF" 
    android:textColor="#ffffff" 
    android:clickable="true" 
    android:gravity="center_vertical|center_horizontal" 
    android:text="@string/Login" /> 

<Button 
    android:id="@+id/Register" 
    android:layout_width="150dp" 
    android:layout_height="40dp" 
    android:layout_centerHorizontal="true" 
    android:layout_marginTop="20dp" 
    android:layout_below="@+id/Login" 
    android:background="#46C1EF" 
    android:textColor="#ffffff" 
    android:clickable="true" 
    android:gravity="center_vertical|center_horizontal" 
    android:text="@string/Register" /> 

<CheckBox 
    android:id="@+id/RememberMe" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/Password" 
    android:layout_below="@+id/Password" 
    android:textColor="#223355" 
    android:text="Remember Me" /> 

</RelativeLayout> 

Answer 1

вы должн ve прокомментировал код, который инициализирует ссылки на кнопки очистки и выхода, но при этом вызывает setOnClickListener() на этих ссылках на кнопки null.

Answer 2

Вы

//clearButton = (Button) findViewById(R.id.Clear); 
//exitButton = (Button) findViewById(R.id.Exit); 

Comemnted, который должен дать вам NUllPointerException. Там может быть больше ошибок, и в этом случае вы должны опубликовать stacktrace.