I'm new to android (and not a veteran at all in java) developpment.
Trying to do a weather app, I'm trying to use TinyDB as my storage for saved cities.
A button on another activity let me add cities to a list (which I want to save).
In my MainActivity's onCreate, I'm setting up my TinyDB. Then add a city stored in extra to my TinyDB if the MainActivity is launched from the addCityActivity. Finally, getting all the cities from TinyDB to print it to screen in a ListView. (user will then be able to click on a city to get weather information for this one)
But then a NullPointerException raises and it seems to come from TinyDB and I have no idea how to resolve it, I'm stuck on it for a day now (doing this on my free time).
Do you guys have any idea please ?
TinyDB is here.
And here's my MainActivity :
public class MainActivity extends AppCompatActivity {
private Context context;
private ListView cityListView;
private CitylistAdapter citylistAdapter;
private List<City> cities = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TinyDB tinydb = new TinyDB(context);
if (getIntent().getExtras() != null) {
String name = getIntent().getStringExtra("City");
ArrayList<String> cityList = tinydb.getListString("Cities");
cityList.add(getIntent().getStringExtra("City"));
tinydb.putListString("Cities", cityList);
}
ArrayList<String> cityList = tinydb.getListString("Cities");
for (int i = 0; i < cityList.size(); i++) {
City city = new City();
city.setName(cityList.get(i));
cities.add(city);
}
this.cityListView = (ListView) findViewById(R.id.cityList);
this.citylistAdapter = new CitylistAdapter(getApplicationContext(), cities);
this.cityListView.setAdapter(citylistAdapter);
FloatingActionButton addCity = (FloatingActionButton) findViewById(R.id.openAddCity);
addCity.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startAddCityActivity();
}
});
}
private void startAddCityActivity() {
Intent intent = new Intent(this, AddCityActivity.class);
startActivity(intent);
}
}
And here's the stack trace :
2021-09-23 13:59:38.565 5754-5754/com.example.weather E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.weather, PID: 5754
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.weather/com.example.weather.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.preference.PreferenceManager.getDefaultSharedPreferencesName(PreferenceManager.java:555)
at android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:545)
at com.example.weather.TinyDB.<init>(TinyDB.java:39)
at com.example.weather.MainActivity.onCreate(MainActivity.java:51)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
2021-09-23 13:59:38.600 5754-5754/com.example.weather I/Process: Sending signal. PID: 5754 SIG: 9
Related
I'm trying to add fragments to the dashboard of my project app. However, I'm getting nullpointerexception
in the .setOnItemSelectedListener in the bottomMenu function, the code is as follows:
Dashboard.java
public class Dashboard extends AppCompatActivity {
ChipNavigationBar chipNavigationBar;
#Override
protected void onCreate(Bundle savedInstanceState) {
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
super.onCreate(savedInstanceState);
chipNavigationBar = findViewById(R.id.bottom_nav_menu);
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new DashboardFragment()).commit();
bottomMenu();
}
private void bottomMenu() {
chipNavigationBar.setOnItemSelectedListener(new ChipNavigationBar.OnItemSelectedListener() {
#Override
public void onItemSelected(int i) {
Fragment fragment = null;
switch (i){
case R.id.bottom_nav_dashboard:
fragment = new DashboardFragment();
break;
case R.id.bottom_nav_explore:
fragment = new ExploreFragment();
break;
case R.id.bottom_nav_profile:
fragment = new ProfileFragment();
break;
}
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragment).commit();
}
});
}
}
LogCat:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.desikhao, PID: 11751
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.desikhao/com.example.desikhao.LocationOwner.Dashboard}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.ismaeldivita.chipnavigation.ChipNavigationBar.setOnItemSelectedListener(com.ismaeldivita.chipnavigation.ChipNavigationBar$OnItemSelectedListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3308)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3457)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2044)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7562)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.ismaeldivita.chipnavigation.ChipNavigationBar.setOnItemSelectedListener(com.ismaeldivita.chipnavigation.ChipNavigationBar$OnItemSelectedListener)' on a null object reference
at com.example.desikhao.LocationOwner.Dashboard.bottomMenu(Dashboard.java:39)
at com.example.desikhao.LocationOwner.Dashboard.onCreate(Dashboard.java:33)
at android.app.Activity.performCreate(Activity.java:7893)
at android.app.Activity.performCreate(Activity.java:7880)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3283)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3457)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2044)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7562)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
At first, I thought the problem is because I stored a null value in the fragment, if that is the case then how do I fix it, I'm new to this so please let me know what am I doing wrong here.
Your chipNavigationBar variable is null and therefore the OnItemSelectedListener is instantiated with null, which is not possible.
You try to find your chipNavigationBar in the Dashboard, but you haven't even set setContentView(R.layout.yourLayout);, which means that it is not possible to find the ViewById.
You have to instatiate the variable in your fragment, where you have a valid view.
chipNavigationBar = findViewById(R.id.bottom_nav_menu);
I am trying to make something that converts the text i write into EditText to speech when i press button01.
It works fine on the virtual machine with Android API 23, but it crashes and makes a NullPointerException and crashes on the virtual machine with Android API 30. Here's the code:
public MainActivity() {
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText);
button01 = (Button) findViewById(R.id.button01);
final TextView textView1 = (TextView) findViewById(R.id.text1) ;
textView1.setText("\n");
tts = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
#Override
public void onInit(int status) {
if(status != ERROR) {
// 언어를 선택한다.
tts.setLanguage(Locale.ENGLISH);
} else {
textView1.setText("TTS 작업에 오류가 생기거나 지원되지 않는 언어입니다.");
tts.speak("TTS 작업에 오류가 생기거나 지원되지 않는 언어입니다.", TextToSpeech.STOPPED, null);
}
}
});
button01.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// editText에 있는 문장을 읽는다.
tts.speak(editText.getText().toString(), TextToSpeech.QUEUE_FLUSH, null);
}
});
}
#Override
protected void onDestroy() {
super.onDestroy();
// TTS 객체가 남아있다면 실행을 중지하고 메모리에서 제거한다.
if(tts != null){
tts.stop();
tts.shutdown();
tts = null;
}
}
}
When i view Logcat, it showes this:
2020-07-09 02:10:56.036 7700-7700/com.example.myapplication2 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.myapplication2, PID: 7700
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication2/com.example.myapplication2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.speech.tts.TextToSpeech.speak(java.lang.String, int, java.util.HashMap)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.speech.tts.TextToSpeech.speak(java.lang.String, int, java.util.HashMap)' on a null object reference
at com.example.myapplication2.MainActivity$1.onInit(MainActivity.java:42)
at android.speech.tts.TextToSpeech.dispatchOnInit(TextToSpeech.java:836)
at android.speech.tts.TextToSpeech.initTts(TextToSpeech.java:814)
at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:745)
at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:724)
at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:708)
at com.example.myapplication2.MainActivity.onCreate(MainActivity.java:34)
at android.app.Activity.performCreate(Activity.java:7995)
at android.app.Activity.performCreate(Activity.java:7979)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
It's happening in the else part in onInit of your listener. When there was an error in initializing the TextToSpeech instance, onInit will be called with ERROR as input while tts is not yet initialized and is null.
It may happen when your device doesn't support text to speech or the engine is missing necessary data.
Don't call anything on tts in case of an error. (There was an error in initializing text to speech. So, how can it speak your text?!)
Apps targeting Android 11 that use text-to-speech should declare TextToSpeech.Engine.INTENT_ACTION_TTS_SERVICE in the queries elements of their manifest:
<queries>
...
<intent>
<action android:name="android.intent.action.TTS_SERVICE" />
</intent>
</queries>
Everytime the application gets to my second activity it crashes, giving the error.
My activity:
public class SecondActivity extends AppCompatActivity {
EditText barcodeText = findViewById(R.id.barcodeText);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
IntentFilter filter = new IntentFilter();
filter.addCategory(Intent.CATEGORY_DEFAULT);
filter.addAction(getResources().getString(R.string.activity_intent_filter_action));
registerReceiver(myBroadcastReceiver, filter);
}
private BroadcastReceiver myBroadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Bundle b = intent.getExtras();
if (action.equals(getResources().getString(R.string.activity_intent_filter_action))) {
try {
displayScanResult(intent);
} catch (Exception e) {
}
}
}
};
private void displayScanResult(Intent initiatingIntent)
{
String decodedSource = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_source));
String decodedData = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_data));
String decodedLabelType = initiatingIntent.getStringExtra(getResources().getString(R.string.datawedge_intent_key_label_type));
barcodeText.setText(decodedData);
}
}
Logcat:
07-01 12:37:03.373 349-349/com.example.provatimer E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.provatimer, PID: 349
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.provatimer/com.example.provatimer.SecondActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5256)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:149)
at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:99)
at android.content.Context.obtainStyledAttributes(Context.java:438)
at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692)
at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479)
at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214)
at com.example.provatimer.SecondActivity.<init>(SecondActivity.java:14)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1606)
at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5256)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
I think it may have something to do with the context in the BroadcastReceiver, but I tried to declare it in the onCreate method but nothing changed.
Maybe I don't initialize correctly the intent in which the data should be stored, if so, how can I do it correctly?
All the Strings should be correct int the string.xml file, if the error may come from that I'll write them.
I think the error is happening here:
EditText barcodeText = findViewById(R.id.barcodeText);
You are invoking findViewById() directly in the class member declaration.
You have invoke findViewById() after setContentView()
EditText barcodeText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
barcodeText = findViewById(R.id.barcodeText);
}
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I am trying for hours to do an extremely simple thing, but for some reason it doesn't work...
I'm trying to go from an activity that is used for Log in, to another activity that is used for signing up.
The rest of the code works perfectly, but whenever I press the textview that supposes to bring me to the Registration screen, the app crashes.
I tried everything, even to use a button instead of textview, and many ways of intents I found online, with "finish" and without "finish", but nothing worked, do you guys have any idea what went wrong?
The Activity is added to the manifest.
Thank you!
public class LoginActivityU extends AppCompatActivity implements View.OnClickListener {
String Uname, Pass;
Button loginButton;
EditText userEt;
EditText passwordEt;
HashMap<String, String> hashMap;
ProgressDialog p;
Boolean check = false;
SharedPreferences sp;
SharedPreferences.Editor editor;
TextView tvSignUp;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
sp=this.getSharedPreferences("LocalLogInData", 0);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
Intent intent = getIntent();
setSupportActionBar(toolbar);
loginButton = (Button) findViewById(R.id.btn_login);
userEt = (EditText) findViewById(R.id.input_uname);
passwordEt = (EditText) findViewById(R.id.input_password);
tvSignUp = (TextView) findViewById(R.id.link_signup);
loginButton.setOnClickListener(this);
tvSignUp.setOnClickListener(this);
Uname = sp.getString("Uname", null);
Pass = sp.getString("Pass", null);
Log.d("dds", Uname + Pass);
if (Uname != null && Pass != null)
{
userEt.setText(Uname);
passwordEt.setText(Pass);
hashMap = new HashMap<String, String>();
hashMap.put("username",userEt.getText().toString());
hashMap.put("password",passwordEt.getText().toString());
Login login=new Login();
login.execute("https://example.com");
if(check == false)
{
editor=sp.edit();
editor.remove("Uname");
editor.remove("Pass");
editor.commit();
}
}
}
#Override
public void onClick(View view) {
if (loginButton.isPressed())
{
hashMap = new HashMap<String, String>();
hashMap.put("username",userEt.getText().toString());
hashMap.put("password",passwordEt.getText().toString());
editor=sp.edit();
editor.putString("Uname",userEt.getText().toString());
editor.putString("Pass",passwordEt.getText().toString());
Login login=new Login();
login.execute("https://peulibrary.co.il/api/user/generate_auth_cookie/");
editor.commit();
}
else if (tvSignUp.isPressed())
{
Intent intent = new Intent(this, SignUpActivity.class);
startActivity(intent);
finish();
}
}
Log of crash:
02-03 14:35:51.661 10836-10836/com.example.negev.peulibraryv201 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.negev.peulibraryv201, PID: 10836
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.example.example/com.example.example.example.SignUpActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.negev.peulibraryv201.SignUpActivity.onCreate(SignUpActivity.java:22)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Looking at the crash log, it seems that you are attaching a click listener to your FloatingActionButton before instantiating it. Please make sure that you call findViewById and instantiate the view first, and only call setOnClickListener after. The problem is in SignUpActivity.
seeing the logs it is clear that the Problem should be in your signup activity.
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)'
indicates that there is a widget you are referring is not initialized or null
Please check whats the problem with my code here :
Main Activity :
I'm using Android Studio. Import statements are managed for me. It won't be necessary to write them here
public class MainActivity extends Activity implements View.OnClickListener {
SharedPreferences prefs;
String dataName = "MyData";
String intName = "MyString";
int defaultInt = 0;
public static int highScore;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button buttonPlay = (Button) findViewById(R.id.btnPlay);
TextView textHighScore = (TextView) findViewById(R.id.textHighScore);
buttonPlay.setOnClickListener(this);
prefs = getSharedPreferences(dataName, MODE_PRIVATE);
highScore = prefs.getInt(intName, defaultInt);
textHighScore.setText("High Score: " + highScore);
}
#Override
public void onClick(View view) {
Intent intent;
intent = new Intent(this, GameActivity.class);
startActivity(intent);
}
}
When I run this application Main Activity is loaded but when I hit play button application closes. I have checked the play button's ID is O.K. I had the same problem in GameActivity but at last I figured out that the problem was with the ID but this time I think problem is with the this I used in Intent();. Activity fails to load.
Exception :
06-24 01:34:05.196 12826-12826/com.cruzerblade.memorygame E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.cruzerblade.memorygame, PID: 12826
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.cruzerblade.memorygame/com.cruzerblade.memorygame.GameActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.content.ContextWrapper.getResources(ContextWrapper.java:87)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:81)
at android.view.animation.AnimationUtils.loadAnimation(AnimationUtils.java:75)
at com.cruzerblade.memorygame.GameActivity.<init>(GameActivity.java:55)
at java.lang.Class.newInstance(Native Method)
at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Please help me out! It took me too much time still I couldn't figure out the problem.
Quoting from your logcat:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method
'android.content.res.Resources android.content.Context.getResources()'
on a null object reference
at android.content.ContextWrapper.getResources(ContextWrapper.java:87)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:81)
at android.view.animation.AnimationUtils.loadAnimation(AnimationUtils.java:75)
at com.cruzerblade.memorygame.GameActivity.<init>(GameActivity.java:55)
This last line is the only line in the trace that is your code:
Look on line 55 of GameActivity.java. It is calling loadAnimation. There is something wrong with the animation it is trying to load (probably a missing resource ID, but it could also be a null or invalid context argument for loadAnimation.)