Develop Reference

No errror shown in android studio but still setOnClickListener works only on one button while on other button it does not work

My java code:
public class StartActivity extends AppCompatActivity {
private Button mRegBtn;
private Button mLoginBtn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_start);
mRegBtn = (Button) findViewById(R.id.start_reg_btn);
mLoginBtn = (Button) findViewById(R.id.start_login_btn);
mRegBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent reg_intent = new Intent(StartActivity.this, RegisterActivity.class);
startActivity(reg_intent);
}
});
mLoginBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent login_intent = new Intent(StartActivity.this, LoginActivity.class);
startActivity(login_intent);
}
});
}
}
The LogCat shows this:
2020-04-30 12:53:42.391 31407-31407/com.example.chattting E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.chattting, PID: 31407
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.chattting/com.example.chattting.LoginActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2947)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3012)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1716)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:232)
at android.app.ActivityThread.main(ActivityThread.java:6802)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1103)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference
at com.example.chattting.LoginActivity.onCreate(LoginActivity.java:43)
at android.app.Activity.performCreate(Activity.java:6974)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2900)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3012) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1716) 
at android.os.Handler.dispatchMessage(Handler.java:110) 
at android.os.Looper.loop(Looper.java:232) 
at android.app.ActivityThread.main(ActivityThread.java:6802) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1103) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964) 

first answer i give.
Based on your log, the line
"Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference" says, that is having trouble setting an AppBar Title.
My bet is that you have some sort of error, in one of the Activities you are trying to start, from the buttons.
If you want more help, tell what is the button that is failing, and send the Other two activities code.

Transporting doubles from one into another activity

I am trying to transport variables that I get through an EditText into the next activity. At first, I tried it with just one variable and it worked fine. But once I added the second activity, the app started to crash
once I tried it out. The app crashes when I try to press the button to get to the second activity.
Maybe you can find the mistake?
Following is my code.
First Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button weiter = (Button) findViewById(R.id.weiter1);
weiter.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
EditText inputHeight = (EditText) findViewById(R.id.inputheight);
EditText inputlenght = (EditText) findViewById(R.id.inputlenght);
Double height = Double.parseDouble(inputHeight.getText().toString());
String Höhe = new Double(height).toString();
Double lenght = Double.parseDouble(inputlenght.getText().toString());
String Länge = new Double(lenght).toString();
Intent i = new Intent(getApplicationContext(), Main2Activity.class);
i.putExtra("HöheName", Höhe);
i.putExtra( "LängeName", Länge);
startActivity(i);
}
});
}
Second Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
Intent intent = getIntent();
String Höhe = intent.getExtras().getString("HöheName");
String Länge = intent.getExtras().getString( "längeName");
double höhe = Double.valueOf(Höhe);
double länge = Double.valueOf(Länge);
double längemalhöhe = höhe + länge;
String ergebnis = new Double(längemalhöhe).toString();
TextView Test = (TextView) findViewById(R.id.Test);
Test.setText(ergebnis);
Button weiter = (Button) findViewById(R.id.weiter2);
weiter.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = getIntent();
String Höhe = intent.getExtras().getString("HöheName");
Intent i = new Intent(getApplicationContext(), Main3Activity.class);
i.putExtra("HöheName", Höhe);
startActivity(i);
}
});
}
Third Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main3);
Intent intent = getIntent();
String Höhe = intent.getExtras().getString("HöheName");
TextView Test = (TextView) findViewById(R.id.Ergebnis2);
Test.setText(Höhe);
}
Here is the Logcat:
12-27 23:02:42.760 30997-30997/com.example.june.test E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.june.test, PID: 30997
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.june.test/com.example.june.test.Main2Activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.trim()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3319)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415)
at android.app.ActivityThread.access$1100(ActivityThread.java:229)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1821)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7331)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.trim()' on a null object reference
at java.lang.StringToReal.parseDouble(StringToReal.java:263)
at java.lang.Double.parseDouble(Double.java:301)
at java.lang.Double.valueOf(Double.java:338)
at com.example.june.test.Main2Activity.onCreate(Main2Activity.java:22)
at android.app.Activity.performCreate(Activity.java:6904)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1136)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3266)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415) 
at android.app.ActivityThread.access$1100(ActivityThread.java:229) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1821) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:7331) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

I don't know if it's just a typo, but you have the line: String Länge = intent.getExtras().getString( "längeName"); where "längeName" is not capital, however, you initially did this: i.putExtra( "LängeName", Länge); where "LängeName" is capital. So the problem might be that the two strings aren't the same. When you try to do the following:
String Länge = intent.getExtras().getString( "längeName");
The string is initialized to null because there is no value assign to "längeName", which can then lead to a NullPointerException if the string is attempted to be used.

From the logcat, I see it says java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.trim() so your app crashes because a you are trying to use a String that is null. You need to check if the Strings you are working with are not null it avoid these crashes.

Notice:
i.putExtra( "LängeName", Länge);
...
String Länge = intent.getExtras().getString( "längeName");
LängeName and längeName are different two keys.

To avoid the simple mistake pointed out by LAD, it is a good practice to store the string with a final modifier.
First Activity
final static String HOHE_NAME = "HöheName";
final static String LANGE_NAME = "LängeName";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//....
Intent i = new Intent(getApplicationContext(), Main2Activity.class);
i.putExtra(HOHE_NAME, Höhe);
i.putExtra(LANGE_NAME, Länge);
startActivity(i);
}
Second Activity
Intent intent = getIntent();
String Höhe = intent.getExtras().getString(MainActivity.HOHE_NAME);
String Länge = intent.getExtras().getString(MainActivity.LANGE_NAME);

Set switch statement based on number of clicks

My application is crashing and I believe it is due to the SharedPreferencesManager prefManager = SharedPreferencesManager.getInstance(this); being stored globally in Contentclass. However, if I take it out of there then I cannot use prefManager within the switch statement further down.
I want to use the number of clicks from prefManager to determine my switch statement. How can I get around this?
public class Content extends AppCompatActivity {
Button selectAnotherButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_content);
final SharedPreferencesManager prefManager = SharedPreferencesManager.getInstance(this);
selectAnotherButton = findViewById(R.id.button_select_another);
selectAnotherButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
prefManager.increaseClickCount();
for (int i = 0; i <= 100; i+=2) {
ShowRewardDialog();
}
}
});
private void ShowRewardDialog() {
String message = "";
//show dialog
// set text based on an if statement you need to create
switch (SharedPreferencesManager.getInstance(this).increaseClickCount()){
case 2 :
message = "You are rewarded with a video";
break;
case 4 :
message = "You are rewarded with a the yellow smiley face in the homepage";
break;
case 6 :
message = "You are rewarded with a video";
break;
case 8 :
message = "You are rewarded with a the green smiley face in the homepage";
break;
case 10 :
message = "You are rewarded with a video";
break;
case 12 :
message = "You are rewarded with a the red smiley face in the homepage";
break;
case 14 :
message = "You are rewarded with a video";
break;
default :
message="";
}
// custom dialog
final Dialog dialog = new Dialog(context);
dialog.setContentView(R.layout.custom_dialog);
SpannableString title = new SpannableString("YOU GAINED A REWARD");
title.setSpan(new ForegroundColorSpan(context.getResources().getColor(R.color.purple))
, 0, title.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
// set the custom dialog components - text, image and button
TextView text = dialog.findViewById(R.id.dialog_text);
dialog.setTitle(title);
text.setText(message);
Button dialogButton = dialog.findViewById(R.id.dialog_button_OK);
// if button is clicked, close the custom dialog
dialogButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dialog.dismiss();
}
});
dialog.show();
}
}
Stack Trace:
06-14 21:57:39.420 15488-15488/com.mima.chilltime E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.mima.chilltime, PID: 15488
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.mima.chilltime/com.mima.chilltime.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2989)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3260)
at android.app.ActivityThread.access$1000(ActivityThread.java:218)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1734)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6934)
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:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:111)
at com.mima.chilltime.SharedPreferencesManager.<init>(SharedPreferencesManager.java:19)
at com.mima.chilltime.SharedPreferencesManager.getInstance(SharedPreferencesManager.java:25)
at com.mima.chilltime.MainActivity.<init>(MainActivity.java:25)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1690)
at android.app.Instrumentation.newActivity(Instrumentation.java:1094)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2979)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3260) 
at android.app.ActivityThread.access$1000(ActivityThread.java:218) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1734) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:145) 
at android.app.ActivityThread.main(ActivityThread.java:6934) 
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:1404) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199) 

Try using
SharedPreferencesManager.getInstance(getApplicationContext());
instead of using this

In the SharedPreferencesManager.getInstance(this); .... this refers to the particular activity (i.e. not global) (i.e. its lifecycle directly related to the current context).
On the other hand, if you clearly need a reference to the global state of your application, then you can use ApplicationContext.
From Android Documentation (my emphasis) :
public Context getApplicationContext()
Return the context of the single, global Application object of the
current process. This generally should only be used if you need a
Context whose lifecycle is separate from the current context, that is
tied to the lifetime of the process rather than the current component.
So change to:
SharedPreferencesManager prefManager = SharedPreferencesManager.getInstance(getApplicationContext());

Android Application crashes when going from an activity to another using intent [duplicate]

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

How to display passed intent data in a TextView - NullPointerException error

I am making an app to display data from a database into a list view. When an item on the list view is clicked, it takes the user to a new activity where they can view more details about that item. I want to make the details page dynamic to display the details and have managed to show the title of the list view item in a toast.
Now, I am trying to display this by using setText() to show the title in a string but am getting the error:
AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.kathe.parenttripapp, PID: 22849
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.kathe.parenttripapp/com.example.kathe.parenttripapp.Details}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.Serializable android.content.Intent.getSerializableExtra(java.lang.String)' 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:5254)
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:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.Serializable android.content.Intent.getSerializableExtra(java.lang.String)' on a null object reference
at com.example.kathe.parenttripapp.Details.<init>(Details.java:23)
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:5254) 
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:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
this is the class the error occurs at:
TextView titletext;
final List<Activitytable> activityTable = Activitytable.listAll(Activitytable.class);
String data = getIntent().getSerializableExtra("listPosition").toString();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
TextView titletext = (TextView) findViewById(R.id.titletext);
String data = getIntent().getSerializableExtra("listPosition").toString();
Toast.makeText(getBaseContext(),String.valueOf(data),Toast.LENGTH_LONG).show();
setData();
}
private void setData() {
Intent i = getIntent();
Bundle b = i.getExtras();
if (data != null) {
String j = (String) b.get("listPosition");
titletext.setText(j);
}
else{
titletext.setText("Hello");
}
}
This is the activity it has come from:
final ListView listView = (ListView) findViewById(R.id.viewAll_listview);
long count = Activitytable.count(Activitytable.class);
if(count>0) {
final List<Activitytable> activitytable = Activitytable.listAll(Activitytable.class);
final ViewAllListView madapter = new ViewAllListView(getApplicationContext(), activitytable);
listView.setAdapter(madapter);
listView.setClickable(true);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?>parent, View v, int position, long id) {
String title = activitytable.get(position).Title.toString();
Activitytable AT = Activitytable.findById(Activitytable.class,activitytable.get(position).getId());
Intent i = new Intent(getApplicationContext(),Details.class);
i.putExtra("listPosition",title);
startActivity(i);
}
public Object getItem(int position) {return position;}
});
}
else
{
Toast.makeText(getApplicationContext(), "No Data Available in Table", Toast.LENGTH_LONG);
}
}
What I would like to do is to put the intent data into the TextView 'titletext' and then do an if statement saying if the passed intent data is equal to an activity title then display the following data but can't work out what is going wrong. I have tried using getStringExtra() instead of getSerializableExtra but no such luck. Works on toast but not on TextView.

If you don't have some good understanding of why you are doing so, try not to initialize your variables until you are in onCreate, also to prevent a NullPointerException, it is a good habit to use if (variable != null).
And you are storing an int, so use getIntExtra
TextView titletext;
List<Activitytable> activityTable;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
activityTable = Activitytable.listAll(Activitytable.class);
titletext = (TextView) findViewById(R.id.titletext);
Intent i = getIntent();
if (i != null) {
String data = i.getStingExtra("listPosition");
titletext.setText(String.valueOf(data));
}
}

In onCreate() and don't do it as a member variable.
Bundle intentBundle = getIntent().getExtras();
if (intentBundle != null) {
lastPosition = getInt( "lastPostion" );
}

The null pointer you are receiving is in the Details class on line 23
at com.example.kathe.parenttripapp.Details.<init>(Details.java:23)