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How to use getIntExtra value as an array index in next activity

So I have a listview that shows 5 chapters of the book of James from the Bible. As the user chooses the chapter he wants to read, the verses from the chapter will show. What I'm trying to do is to get position value from JamesChapter.java to be passed to the next activity Bible.java and use that value as an index value to the array I want to access in my json file that will display the verses. What happens is the app crashes when I click the chapter. I tried using getIntent() and getIntExtra() but I don't know how to use the value from those method to apply as an array index. Appreciate the help on how I can use the value from last activity to the array in my next activity. have a great day
public class JamesChapters extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_book_chapters);
ListView listView = findViewById(R.id.listview);
List<String> list = new ArrayList<>();
list.add("Chapter 1");
list.add("Chapter 2");
list.add("Chapter 3");
list.add("Chapter 4");
list.add("Chapter 5");
ArrayAdapter arrayAdapter = new ArrayAdapter(getApplicationContext(), android.R.layout.simple_list_item_1,list);
listView.setAdapter(arrayAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent intent = new Intent(JamesChapters.this, Bible.class);
intent.putExtra("position", position);
startActivity(intent);
}
});
}
}
public class Bible extends AppCompatActivity {
TextView tvReference, tvVersion, tvVerse;
String reference, version, verse;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bible);
Intent intent = getIntent();
int position = intent.getIntExtra("position",0);
displayJArray(position);
}
public void displayJArray(int value){
String rid = rid();
try{
JSONObject json = new JSONObject(rid);
JSONArray jsonarray = json.getJSONArray("James");
JSONObject newjson = jsonarray.getJSONObject(value);
reference = newjson.getString("Reference");
version = newjson.getString("Version");
verse = newjson.getString("Verse");
tvReference.setText(reference);
tvVersion.setText(version);
tvVerse.setText(verse);
} catch (JSONException e) {
e.printStackTrace();
}
}
public String rid(){
String content="";
try{
InputStream ist = getAssets().open("james.json");
int size = ist.available();
byte [] buffer = new byte[size];
ist.read(buffer);
content = new String(buffer);
}catch (IOException e) {
e.printStackTrace();
}
return content;
}
}
This is the format of my json file
{
"James": [
{
"Reference": "James 1:1-27",
"Version": "NIV",
"Verse": "......"
},
{
"Reference": "James 2:1-26",
"Version": "NIV"
"Verse": "....."
}
]}
Here is the error from logcat
2022-11-02 15:51:32.805 25637-25676/ph.edu.nu.soco.finalproject E/eglCodecCommon: GoldfishAddressSpaceHostMemoryAllocator: ioctl_ping failed for device_type=5, ret=-1
2022-11-02 15:51:42.272 25637-25637/ph.edu.nu.soco.finalproject E/AndroidRuntime: FATAL EXCEPTION: main
Process: ph.edu.nu.soco.finalproject, PID: 25637
java.lang.RuntimeException: Unable to start activity ComponentInfo{ph.edu.nu.soco.finalproject/ph.edu.nu.soco.finalproject.Bible}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at ph.edu.nu.soco.finalproject.Bible.displayJArray(Bible.java:37)
at ph.edu.nu.soco.finalproject.Bible.onCreate(Bible.java:25)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:193) 
at android.app.ActivityThread.main(ActivityThread.java:6669) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
2022-11-02 15:51:43.018 25695-25721/ph.edu.nu.soco.finalproject E/eglCodecCommon: GoldfishAddressSpaceHostMemoryAllocator: ioctl_ping failed for device_type=5, ret=-1

Your app is crashing because you have defined tvReference but it is not initialized and then you're trying to access it in displayJArray() method which results in a NullPointerException at runtime because Android fails to locate the view in Activity. Initialize your textViews in onCreate Method like the example below.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bible);
// Initialize views like this
tvReference = findViewById(R.id.id_of_your_textView_in_xml);
tvVersion = same as above ;
tvVerse = same as above;
Intent intent = getIntent();
int position = intent.getIntExtra("position",0);
displayJArray(position);
}

How to make the AsyncTask "doInBackground()" wait for an arraylist

I want to save some objects in the local SQL DB on my android device.
If I try to run the app, I get a null object reference error on the cell ArrayList in onPostExecute().
public class CellApiTask extends AsyncTask> {
private Context context;
public CellApiTask(Context context) {
this.context = context;
}
#Override
protected ArrayList<Cell> doInBackground(Void... params) {
Fragment_Battery_Cell_Voltage cellVoltageClass = new Fragment_Battery_Cell_Voltage();
return cellVoltageClass.getCellsForDB();
}
#Override
protected void onPostExecute(ArrayList<Cell> cell) {
CellDbHelper dbHelper = new CellDbHelper(context);
try{
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
try {
/* delete old db if it exists */
db.delete(CellEntryContract.CellEntry.TABLE_NAME_CELL, null, null);
} catch (Exception e){
}
for (int i = 0; i<cell.size();i++) {
values.put(CellEntryContract.CellEntry.COLUMN_NAME_CELL_NUMBER, cell.get(i).getCellNo());
values.put(CellEntryContract.CellEntry.COLUMN_NAME_CELL_DENSITY, cell.get(i).getDensity());
values.put(CellEntryContract.CellEntry.COLUMN_NAME_CELL_VOLTAGE, cell.get(i).getCellVoltage());
db.insert(CellEntryContract.CellEntry.TABLE_NAME_CELL, null, values);
}
Log.i(CellStorage.class.toString(),"Cells successful saved");
}catch(Exception ex) {
Log.e(CellStorage.class.toString(), "Could not save cells in local data storage. ", ex);
} finally {
if (dbHelper != null)
dbHelper.close();
}
}
Fragment:
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
....
amountOfCells = (((AnnualServiceActivity) getActivity()).getBatteryFromIntent().getCell().intValue());
generateGrid();
CellStorage cellStorage = new CellStorage(getContext());
cellStorage.runCellApiTasks();
return view;
}
....
public ArrayList<Cell> getCellsForDB() {
for (int i = 0; i < amountOfCells; i++) {
Cell cell = new Cell();
cell.setCellNo(i + 1);
cell.setCellVoltage(0);
cell.setDensity(0);
Log.i("öööööööööööö",cellsForDB.get(i).getCellNo()+"");
cellsForDB.add(cell);
}
return cellsForDB;
}
...
I think the doInBackground(...) method finished befor the ArrayList is ready in getCellsForDB() maybe thats because I get the null object reference error. So is it possible to make the method wait until the ArrayList from getCellsForDB() is ready?
crash log:
08-07 15:43:54.388 1585-1585/frontend.datastorage.CellStorage: Could not save cells in local data storage.
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
at CellApiTask.onPostExecute(CellApiTask.java:49)
at CellApiTask.onPostExecute(CellApiTask.java:20)
at android.os.AsyncTask.finish(AsyncTask.java:660)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:677)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6692)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)
08-07 15:43:54.392 1585-1585/fronius.com.serviceapp_frontend E/class fronius.com.serviceapp_frontend.datastorage.CellStorage: Could not save cells in local data storage.
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
at CellApiTask.onPostExecute(CellApiTask.java:49)
at CellApiTask.onPostExecute(CellApiTask.java:20)
at android.os.AsyncTask.finish(AsyncTask.java:660)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:677)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6692)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)

You don't have to wait for anything here, the doInBackground method finishes its execution when cellVoltageClass.getCellsForDB() returns. getCellsForDB() seems to return null, because cellsForDB is null (the only reason you don't get the crash earlier is because amountOfCells is 0 and the for inside getCellsForDB() doesn't loop)

Null Pointer Exception on Edit Text Android [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 5 years ago.
I'm writing a program to save user input from the edit text and inserting the text into a listview. I keep getting this null exception even though I've declared the Edit Text already.
public class AddEditAlbum extends AppCompatActivity {
/**
* These keys are to send back and forth information between the bundles and intents
*/
public static final String ALBUM_INDEX = "albumIndex";
public static final String ALBUM_NAME = "albumName";
EditText input;
Button save, cancel;
int albumIndex;
#Override
protected void onCreate(Bundle savedInstanceState) {
save = (Button) findViewById(R.id.save);
cancel = (Button) findViewById(R.id.cancel);
input = (EditText) findViewById(R.id.add);
// see if info was passed in to populate field
Bundle bundle = getIntent().getExtras();
if (bundle != null) {
albumIndex = bundle.getInt(ALBUM_INDEX);
input.setText(bundle.getString(ALBUM_NAME));
}
super.onCreate(savedInstanceState);
setContentView(R.layout.add_album);
}
public void Cancel(View view) {
setResult(RESULT_CANCELED);
finish(); //Returns to previous page on call stack
}
public void addAlbum(View view){
String name = input.getText().toString(); //Fix this, goes to null pointer
//Checks to see if input is null and returns
if(name == null || name.length()==0){
Toast.makeText(AddEditAlbum.this, "Enter valid album name", Toast.LENGTH_SHORT).show();
Bundle bundle = new Bundle();
bundle.putString(AlbumDialog.MESSAGE_KEY, "Album Name Required");
DialogFragment newFragment = new AlbumDialog();
newFragment.setArguments(bundle);
newFragment.show(getFragmentManager(), "badfields");
return;
}
//Toast.makeText(AddEditAlbum.this, "Enter valid album name", Toast.LENGTH_SHORT).show();
Bundle bundle = new Bundle();
bundle.putInt(ALBUM_INDEX, albumIndex);
bundle.putString(ALBUM_NAME, name);
// send back to caller
Intent intent = new Intent();
intent.putExtras(bundle);
setResult(RESULT_OK,intent);
finish();
}
}
public class MainActivity extends AppCompatActivity {
ListView listView;
private ArrayList<Album> albums;
public static final int EDIT_ALBUM_CODE = 1;
public static final int ADD_ALBUM_CODE = 2;
#Override
protected void onCreate(Bundle savedInstanceState) {
listView = (ListView) findViewById(R.id.album_list);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void Create(View view){
Intent intent = new Intent(this, AddEditAlbum.class);
startActivityForResult(intent, ADD_ALBUM_CODE);
}
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
if (resultCode != RESULT_OK) {
return;
}
Bundle bundle = intent.getExtras();
if (bundle == null) {
return;
}
// gather all info passed back by launched activity
String name = bundle.getString(AddEditAlbum.ALBUM_NAME);
int index = bundle.getInt(AddEditAlbum.ALBUM_INDEX);
if (requestCode == EDIT_ALBUM_CODE){
Album album = albums.get(index);
album.albumName = name;
}
else if (requestCode == ADD_ALBUM_CODE){
ArrayList<Photo> photos = new ArrayList<>();
albums.add(new Album(name, photos));
}
// redo Adapter since source content has changed
//listView.setAdapter(new ArrayAdapter<Album>(this, album, albums));
}
So this is the full error I'm getting,
FATAL EXCEPTION: main
Process: com.example.mustu.androidphotos31, PID: 9965
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5610) 
at android.view.View$PerformClick.run(View.java:22265) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
at com.example.mustu.androidphotos31.AddEditAlbum.addAlbum(AddEditAlbum.java:54)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:5610) 
at android.view.View$PerformClick.run(View.java:22265) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

super.onCreate(savedInstanceState);
setContentView(R.layout.add_album);
This has to be executed first, otherwise the contentView is not set and findViewById will not find anything, resulting in the EditText being null.

update your onCreate() like this.
we should call setContentView(R.layout.your_layout) for passing the layout to the java class, then only it's views can be used.. failing to do so, will lead to NPE.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add_album);
save = (Button) findViewById(R.id.save);
cancel = (Button) findViewById(R.id.cancel);
input = (EditText) findViewById(R.id.add);
// see if info was passed in to populate field
Bundle bundle = getIntent().getExtras();
if (bundle != null) {
albumIndex = bundle.getInt(ALBUM_INDEX);
input.setText(bundle.getString(ALBUM_NAME));
}
}

#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.album_list);
}
Also You are calling your listview before onCreate method thus giving you a NPE

Android Retrofit "Attempt to invoke virtual method on a null object reference"

Hi first of all i searched some similar questions like mine but unfortunately i couldn't find the similarity of my code to them so please here me out
I have a Main Activity Class
public class MainActivity extends AppCompatActivity {
public ProgressDialog loading;
public String[] itemer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RetrofitHandler handler = new RetrofitHandler();
handler.getContacts(MainActivity.this);
}
public void getter(String[] response, int size) {
String[] itemer;
itemer = new String[size];
if (response != null) {
itemer = response;
Toast.makeText(MainActivity.this, itemer[0], Toast.LENGTH_SHORT).show();
}
}
And a Handler for my result
public class RetrofitHandler {
public String[] item;
public static final String ROOT_URL = "http://api.androidhive.info";
public List<Contacts> contacts;
// final MainActivity main = new MainActivity();
public void getContacts(final Context context) {
final ProgressDialog loading = ProgressDialog.show(context, "Fetching Data", "Please wait...", false, false);
RestAdapter adapter = new RestAdapter.Builder().setEndpoint(ROOT_URL).build();
ContactsAPI api = adapter.create(ContactsAPI.class);
api.getContacts(new Callback<Contacts>() {
#Override
public void success(Contacts contacts, Response response) {
loading.dismiss();
MainActivity update = new MainActivity();
List<Contact> contactList = contacts.getContacts();
item = new String[contactList.size()];
int size = contactList.size();
for (int i = 0; i < contactList.size(); i++) {
item[i] = contactList.get(i).getName();
}
update.getter(item, size);
}
#Override
public void failure(RetrofitError error) {
Toast.makeText(context, "Error Occured", Toast.LENGTH_LONG).show();
}
});
}
But I get an error on my response in the main activity here is my log
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.support.v7.app.AppCompatActivity.getResources(AppCompatActivity.java:542)
at android.widget.Toast.<init>(Toast.java:102)
at android.widget.Toast.makeText(Toast.java:259)
at com.exist.kelvs.retrofit2.MainActivity.getter(MainActivity.java:55)
at com.exist.kelvs.retrofit2.RetrofitHandler$1.success(RetrofitHandler.java:41)
at com.exist.kelvs.retrofit2.RetrofitHandler$1.success(RetrofitHandler.java:28)
at retrofit.CallbackRunnable$1.run(CallbackRunnable.java:45)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
I maked sure that the handler item where not null tested it with toast but when i pass it to getter it gives me the error where did i do wrong? :(

MainActivity update = new MainActivity();
Never instantiate activities with new. They are not initialized to be useful.
Instead, you can pass your activity as a reference where needed. Change
public void getContacts(final Context context)
to e.g.
public void getContacts(final MainActivity mainActivity)
and use mainActivity where you need an activity Context (such as with Dialogs) and when you need to invoke a method on MainActivity.
Note that generally passing activity references to async operations can be prone to significant memory leaks, and you need to take activity lifecycle into account - the activity might not be active when the async operation finishes.

try to delete the toast in your main activity or replace Mainactivity.this to getApplicationContext() .
from :
Toast.makeText(MainActivity.this, itemer[0], Toast.LENGTH_SHORT).show();
to :
Toast.makeText(getApplicationContext(), itemer[0], Toast.LENGTH_SHORT).show();

Why does my Activity get destroyed upon adding a fragment (#2)?

I want to make it clear that this question will look very similar to one I asked earlier, but that I'm not asking exactly the same thing.
In my previous question, I got a RuntimeException/IllegalStateException, which told me my Activity got destroyed upon adding a new fragment.
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp
/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException:
Activity has been destroyed
In that case, it turned out it had to do with me creating new instances of MainActivityin an invalid way:
MainActivity ma = new MainActivity();
(PSA: Don't do the above, use MainActivity ma = (MainActivity) getActivity(); instead.)
I have now corrected this in my entire project, and am getting almost exactly the same error. Let me be clear: I (think I) know the original error was fixed, because I got a different error in between these two RE's, which I was able to fix myself.
To reiterate on my gibberish: Got the first RE, fixed it with the answer on my question, got a different error, fixed that myself, got almost exactly the same RE.
I have searched through my entire project to see if I had anything similar to the error I made before, but I can't find anything, so here I am. So basically, the answer I got on my previous question fixed my issue, temporarily. That answer however, does not help me with this new error I'm getting, that's why I'm asking this question.
TL;DR: Answer on Q1 fixed my issue at first(which makes it a working answer), but it does not fix the issue I'm having right now, which is almost the same.
The actual question
So, now we've got that bit out of the way, let's get on with my issue. So, I'm getting a RuntimeException/IllegalStateExcetion:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}:
java.lang.IllegalStateException: Activity has been destroyed
(PS. It's only a RE because I have my app navigate to the GeneralSettings fragment on startup, for debugging ease.)
I've read up on this kind of error, but nothing I could find that applies on my project.
So, what is causing this RuntimeException/IllegalStateException?
Full log
04-05 14:17:53.140 23411-23411/? I/art: Not late-enabling -Xcheck:jni (already on)
04-05 14:17:53.190 23411-23411/com.example.tim.timapp W/System: ClassLoader referenced unknown path: /data/app/com.example.tim.timapp-1/lib/x86_64
04-05 14:17:53.210 23411-23411/com.example.tim.timapp D/TEST DBHandler: sInstance == null
04-05 14:17:53.370 23411-23411/com.example.tim.timapp D/AndroidRuntime: Shutting down VM
04-05 14:17:53.370 23411-23411/com.example.tim.timapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tim.timapp, PID: 23411
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException: Activity has been destroyed
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.IllegalStateException: Activity has been destroyed
at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1433)
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:687)
at android.app.BackStackRecord.commit(BackStackRecord.java:663)
at com.example.tim.timapp.MainActivity.DrawVariableFragments(MainActivity.java:276)
at com.example.fragments.Settings.GeneralSettingsFragment.onCreateView(GeneralSettingsFragment.java:58)
at android.app.Fragment.performCreateView(Fragment.java:2220)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:973)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
at android.app.BackStackRecord.run(BackStackRecord.java:793)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1535)
at android.app.FragmentController.execPendingActions(FragmentController.java:325)
at android.app.Activity.performStart(Activity.java:6252)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
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) 
MainActivity (Snippet)
package com.example.tim.timapp;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private static boolean isMainShown = false;
private static boolean isSettingsShown = false;
private static boolean doSavePopup = false;
private static String backTitle = "";
private String tag = "TEST MA";
DBHandler dbHandler;
Menu menu;
public void DrawVariableFragments(String base,String token){
// FragmentManager fm = getFragmentManager();
ArrayList<String> Data;
dbHandler = DBHandler.getInstance(this);
int AmountOfEntries;
int SettingsContainer;
String SettingsTag;
Fragment SettingsVariableFragment;
Fragment SettingsEmptyFragment;
if (base.equalsIgnoreCase("StuffManager")) {
Data = new ArrayList<String>() {{add("StuffManager"); add("name"); add("tag"); }};
SettingsContainer = R.id.FragmentContainer2;
SettingsTag = getString(R.string.navdrawer_stuffmanager);
SettingsVariableFragment = new StuffManagerVariableFragment();
SettingsEmptyFragment = new StuffManagerEmptyFragment();
} else if (base.equalsIgnoreCase("GeneralSettings")) {
Data = new ArrayList<String>() {{add("GeneralSettings"); add("name"); add("ip"); add("port"); add("username"); add("pass"); }};
SettingsContainer = R.id.FragmentContainerGeneralSettings;
SettingsTag = getString(R.string.navdrawer_generalsettings);
SettingsVariableFragment = new GeneralSettingsVariableFragment();
SettingsEmptyFragment = new GeneralSettingsEmptyFragment();
} else {
Log.e(tag, "String Base not recognised");
return;
}
AmountOfEntries = dbHandler.returnArray(base, Data.get(1)).size();
FragmentManager fm = getFragmentManager().findFragmentByTag(SettingsTag).getChildFragmentManager();
if ((dbHandler.returnArray(base, Data.get(1))).size() == 0 ) {
// Log.d(tag, "SettingsContainer1: " + String.valueOf(SettingsContainer) + "; SettingsEmtpyFragment1: " + SettingsEmptyFragment + "; Base1: " + base);
fm.beginTransaction().add(SettingsContainer, SettingsEmptyFragment, (base + "EmptyFragment")).commit();
fm.executePendingTransactions();
return;
}
if (AmountOfEntries > 0) {
String EmptyFragName = (base + "EmptyFragment");
if ((fm.findFragmentByTag(EmptyFragName)) != null) {
fm.beginTransaction().remove(fm.findFragmentByTag(EmptyFragName)).commit();
fm.executePendingTransactions();
}
for (int i = 0; i < AmountOfEntries; i++) {
ArrayList<String> fragmentData = new ArrayList<>();
for (int k=1; k < Data.size(); k++) {
int j=k-1;
fragmentData.set(j, (dbHandler.returnArray(base, Data.get(k)).get(j)));
}
if (token.equalsIgnoreCase("edit")) {
LinearLayout linearLayout = (LinearLayout) findViewById(SettingsContainer);
linearLayout.removeAllViews();
DrawVariableFragments(base ,"draw");
} else if (token.equalsIgnoreCase("add")) {
if (fm.findFragmentByTag(fragmentData.get(i)) == null) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
} else if (token.equalsIgnoreCase("draw")) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
}
} else {
Log.d("TEST", "WTF, nameArray.size != 0 && !> 0");
}
}
}
GeneralSettingsFragment (Snippet)
package com.example.fragments.Settings;
public class GeneralSettingsFragment extends Fragment {
MainActivity ma;
DBHandler dbHandler;
private static Menu optionsMenu;
public static boolean hideDeleteAllButton = false;
LinearLayout linearLayout;
View rootView;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_generalsettings, container, false);
ma = (MainActivity) getActivity();
linearLayout = (LinearLayout) rootView.findViewById(R.id.FragmentContainerGeneralSettings);
if (linearLayout == null) {
Log.e("GMF", "Layout is null");
} else if (linearLayout.getChildCount() == 0) {
GeneralSettingsInitialInputDialog GSIID = new GeneralSettingsInitialInputDialog();
GSIID.show(getFragmentManager(), "dialog");
hideDeleteAllButton = true;
} else {
hideDeleteAllButton = false;
}
ma.DrawVariableFragments("GeneralSettings", "draw");
return rootView;
}
}

You are still doing things in an unsupported way. In MainActivity.DrawVariableFragments() you are creating a new GeneralSettingsVariableFragment() and then call getChildFragmentManager() on it and attempt to commit a fragment.
The GeneralSettingsFragment has not yet been attached to an Activity so it does not have a host. This throws the IllegalStateException("Activity has been destroyed") exception you are seeing when you try to commit the FragmentTransaction.
It is unclear why you are creating a new GeneralSettingsVariableFragmentwhen you are already inside a new instance of one.
To properly lookup an existing fragment use getFragmentManager().findFragmentByTag(...) or getFragmentManager().findFragmentById(...).