Android java.lang.NullPointerException: println needs a message
15,992
In the catch block e.getMessage()
may be null
. Try this:
String msg = (e.getMessage()==null)?"Login failed!":e.getMessage();
Log.i("Login Error1",msg);
Author by
jeff7
Updated on June 04, 2022Comments
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jeff7 almost 2 years
I have a problem with my app when I try to login.
In fact, if I register (if the checkbox
remerberMe
isChecked()
on register action, at the next connection the main activity is displayed otherwise the login activity appears) first, it works fine.However, the
Login
Activity doesn't work when it's called on the next connection after register action.Login Activity
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.login); setTitle(R.string.loginTitle); // Importing all assets like buttons, text fields inputUsername = (EditText) findViewById(R.id.username_value); inputPassword = (EditText) findViewById(R.id.password_value); btnLogin = (Button) findViewById(R.id.loginButton); btnExit = (Button) findViewById(R.id.exitButton); btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegister); rememberMe = (CheckBox) findViewById(R.id.rememberNameRegister); // Login button Click Event btnLogin.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { LoginAction(); } }); // Link to Register Screen btnLinkToRegister.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Intent i = new Intent(getApplicationContext(), RegisterActivity.class); startActivity(i); finish(); } }); btnExit.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { finish(); } }); } public void LoginAction() { Log.i("Login", "Login Action"); progressDialog = ProgressDialog.show(LoginActivity.this, null, getResources().getString(R.string.loginProgressMessage), true); // try { runOnUiThread(new Runnable() { String username = inputUsername.getText().toString(); String password = inputPassword.getText().toString(); @Override public void run() { Log.i("Login Run", "username " + username); switch (username.length()) { case 0: blankUserName(); break; } switch (password.length()) { case 0: blankPassWord(); // thread.stop(); break; } try { if (username.length() > 0 && password.length() > 0) { Log.i("Login Run", "password " + password); // Password pass = new Password(username, password); DatabaseHelper db = new DatabaseHelper( getApplicationContext()); int count = db.getRowCount(); Log.i("Login", "getRowCompte " + count); if (count == 1) { Log.i("Login","getLogin1 "); // if (db.getLogin(username, password) == 1) { if (db.Login(username, password)== true) { Log.i("Login", "rememberMe.isChecked()"); if (rememberMe.isChecked() == true) { statut = "on"; } else if (rememberMe.isChecked() == false) { statut = "off"; } Log.i("Login", "ok ischecked"); Log.i("Login","getRowCompteStat "+ db.getRowCountStat()); if (db.getRowCountStat() == 1) { db.UpdateStatut(statut); Log.i("Login", "getRowCompte " + count); } Toast.makeText(getApplicationContext(), "Student Moyenne \n Bienvenu!", Toast.LENGTH_LONG).show(); Log.i("Login Run", "Connecté"); Intent moy = new Intent( getApplicationContext(), MoyenneMain.class); // Close all views before launching // Dashboard moy.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(moy); finish(); db.close(); } else if (db.Login(username, password)==false){ // if (db.getLogin(username, password) == 0) { // Log.i("Login Run", "faux password"); Toast.makeText(LoginActivity.this,"Invalid Username/Password",Toast.LENGTH_LONG).show(); Intent login = new Intent(getApplicationContext(),LoginActivity.class); login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(login); finish(); db.close(); } } else if (count == 0) { Log.i("Login Run", "Enregistrez vous"); Toast.makeText(LoginActivity.this, "Enregistrez vous!", Toast.LENGTH_SHORT) .show(); Intent register = new Intent( getApplicationContext(), RegisterActivity.class); register.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(register); finish(); db.close(); } } } catch (Exception e) { Log.i("Login Error1", e.getMessage()); Toast.makeText(LoginActivity.this, e.getMessage(), Toast.LENGTH_LONG).show(); } } }); // } catch (Exception e) { // Thread.currentThread().destroy(); // Log.i("Login Error2", e.getMessage()); // Toast.makeText(LoginActivity.this, e.getMessage(), // Toast.LENGTH_LONG).show(); // } } private void blankUserName() { Toast.makeText(LoginActivity.this, "Entrez un nom Utilisateur SVP!", Toast.LENGTH_SHORT).show(); Intent login = new Intent(getApplicationContext(), LoginActivity.class); login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(login); finish(); } private void blankPassWord() { Toast.makeText(LoginActivity.this, "Entrez un mot de passe SVP!", Toast.LENGTH_SHORT).show(); Intent login = new Intent(getApplicationContext(), LoginActivity.class); login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(login); finish(); }
A part of DatabaseHelper
public int getRowCountStat() { String countQuery = "SELECT * FROM " + TABLE_STATUT; SQLiteDatabase db = this.getReadableDatabase(); Cursor cursor = db.rawQuery(countQuery, null); int rowCount = cursor.getCount(); db.close(); cursor.close(); // return row count return rowCount; } public int getRowCount() { String countQuery = "SELECT * FROM " + TABLE_LOGIN; SQLiteDatabase db = this.getReadableDatabase(); Cursor cursor = db.rawQuery(countQuery, null); int rowCount = cursor.getCount(); db.close(); cursor.close(); // return row count return rowCount; } public boolean Login(String username, String password) throws SQLException { Cursor mCursor = db.rawQuery("SELECT * FROM " + TABLE_LOGIN + " WHERE username=? AND password=?" , new String[]{username,password}); if (mCursor != null) { if(mCursor.getCount() > 0) { return true; } } return false; } public int UpdateStatut(String statut) { final static int idStat = 1; SQLiteDatabase db = this.getWritableDatabase(); ContentValues cv = new ContentValues(); cv.put(STATUT, statut); return db.update(TABLE_STATUT, cv, ID_STAT + "=?", new String[] { String.valueOf(idStat) }); }
Logcat
10-24 01:48:08.819: E/AndroidRuntime(29242): FATAL EXCEPTION: main 10-24 01:48:08.819: E/AndroidRuntime(29242): java.lang.NullPointerException: println needs a message 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.util.Log.println_native(Native Method) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.util.Log.i(Log.java:143) 10-24 01:48:08.819: E/AndroidRuntime(29242): at com.android.moyenne.activity.LoginActivity$4.run(LoginActivity.java:163) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.app.Activity.runOnUiThread(Activity.java:3707) 10-24 01:48:08.819: E/AndroidRuntime(29242): at com.android.moyenne.activity.LoginActivity.LoginAction(LoginActivity.java:78) 10-24 01:48:08.819: E/AndroidRuntime(29242): at com.android.moyenne.activity.LoginActivity$1.onClick(LoginActivity.java:46) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.view.View.performClick(View.java:2408) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.view.View$PerformClick.run(View.java:8816) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.os.Handler.handleCallback(Handler.java:587) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.os.Handler.dispatchMessage(Handler.java:92) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.os.Looper.loop(Looper.java:123) 10-24 01:48:08.819: E/AndroidRuntime(29242): at android.app.ActivityThread.main(ActivityThread.java:4627) 10-24 01:48:08.819: E/AndroidRuntime(29242): at java.lang.reflect.Method.invokeNative(Native Method) 10-24 01:48:08.819: E/AndroidRuntime(29242): at java.lang.reflect.Method.invoke(Method.java:521) 10-24 01:48:08.819: E/AndroidRuntime(29242): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 10-24 01:48:08.819: E/AndroidRuntime(29242): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 10-24 01:48:08.819: E/AndroidRuntime(29242): at dalvik.system.NativeStart.main(Native Method) 10-24 01:48:12.260: I/Process(29242): Sending signal. PID: 29242 SIG: 9
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jeff7 over 10 yearsI have done it, but now the message "Login failed!" appears in the logcat, and in the Toast (so e.getmessage returns null) and the Thread do not destroy automatically however
getRowCount()
returns 1 and the username and password that i entrer is the same than i entrered on registration. sodb.Login(username, password)
should return true but it returns false. to destroy the thread i want to useThread.currentThread().destroy();
but destroy() is strikethrough. help me please -
Amulya Khare over 10 yearsSince it is going to the catch block, first thing you should do is find out what exception was thrown, do a
e.printStackTrace()
in the catch and report the error log. Also, since it is completely unrelated issue than what you had asked before, you might want to close this question and ask a new one so more people can help you out.