We Keep Coding

how is onActivityResult is different from registerForActivityResult?

actually previously i wanted to pick image fromthe gallery so i came
to know that onActivityResult was deprecated and we should use
registerForActivityResult(). so i used it by defining the mime type
as "image/*" but now i want to import pdf from gallery but there is
no such mime type for that i want to understand how these mime
things works and how can i achieve my task by
registerForActivityResult() method
i also want to understand the how we define the datatype of the someActivityResultLauncher as a string ?? i want to understand how this whole things work...can we define custom mime type by our own ?? please help me in this
'''
package com.parth.iitktimes;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.material.card.MaterialCardView;
import java.io.IOException;
public class addBooks extends AppCompatActivity {
private MaterialCardView selectImage;
private TextView docName;
private Spinner semSpinner, branchSpinner;
private Button btnUpload;
private ActivityResultLauncher<String> someActivityResultLauncher; // why string
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_books);
selectImage = findViewById(R.id.select_image);
docName = findViewById(R.id.tvDocName);
semSpinner = findViewById(R.id.spinner_sem);
branchSpinner = findViewById(R.id.spinner_branch);
btnUpload = findViewById(R.id.btnUploadNotes);
btnUpload.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast.makeText(getApplicationContext(), "uploaded notes successfully", Toast.LENGTH_SHORT).show();
}
});
selectImage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
someActivityResultLauncher.launch("");//what used i fill here??
}
});
String[] semesterItems = {"First", "Second", "Third", "Fourth", "Fifth", "Sixth", "Seventh", "Eighth"};
//attaching array adapter to the spinner
//since we not using custom spinner therefore we are using the default array adapter
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, semesterItems);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
semSpinner.setAdapter(adapter);
//on item selected listener to the spinner
semSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
imageCategory = eventSpinner.getSelectedItem().toString();
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
//setting the default category as others
imageCategory = spinnerItems[0];
}
});
String[] branchItems = {"Mchanical", "Electrical", "CSE", "MTH"};
//attaching array adapter to the spinner
//since we not using custom spinner therefore we are using the default array adapter
ArrayAdapter<String> branchAdapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, branchItems);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
branchSpinner.setAdapter(adapter);
//on item selected listener to the spinner
branchSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
imageCategory = eventSpinner.getSelectedItem().toString();
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
//setting the default category as others
imageCategory = spinnerItems[0];
}
});
//activity result launcher
someActivityResultLauncher = registerForActivityResult(
new ActivityResultContracts.GetContent(), new ActivityResultCallback<Uri>() {
#Override
public void onActivityResult(Uri result) {
try {
bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), result);
} catch (IOException e) {
e.printStackTrace();
}
preview_events_image.setImageBitmap(bitmap);
}
});
}
}

How to load, save, and show array to list?

I have XML layout like this:
[....textedit....][addbutton]
=======list1=========
=======list2=========
=======list3=========
=======list4=========
What to do if I want to Load and Show the list onCreate from SharePreferences, be able to Add "item" to the list, and save it to SharedPreferences? Any extra simple beginner explanation are welcome since I'm a total newb.
My code below is a big mess, and I got it 100% from stitching from one example to another example that I got from anywhere.
package com.mycompany.myapp;
import android.app.*;
import android.os.*;
import android.widget.EditText;
import android.widget.Button;
import android.widget.ListView;
import android.widget.ListAdapter;
import android.widget.ArrayAdapter;
import android.widget.AdapterView;
import android.widget.Toast;
import android.view.View;
import android.content.SharedPreferences;
import android.content.Context;
public class MainActivity extends Activity {
String FileName = "myFile";
Button BtnSave;
EditText editName;
ListView lv;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
BtnSave = findViewById(R.id.btn1);
BtnSave.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
saveFile();
}
});
lv = (ListView) findViewById(R.id.list1);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,empty);
lv.setAdapter(adapter);
//Setting onClickListener on ListView
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Toast.makeText(getApplicationContext(),"Item Clicked: "+i,Toast.LENGTH_SHORT).show();
}
});
editName = findViewById(R.id.edit1);
}
private void saveFile() {
String strName = editName.getText().toString();
SharedPreferences sharedPref = getSharedPreferences(FileName,Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("name", strName);
editor.commit();
Toast.makeText(this,"Data Saved Successfully",Toast.LENGTH_SHORT).show();
}
}

I think this should help you.
fun addProduct(productsItem: Product) {
sharedPreferences=context.getSharedPreferences(TAG,Context.MODE_PRIVATE)
var gson=Gson()
var cartProduct=getAllProducts()
cartProduct.add(productsItem)
var json=gson.toJson(cartProduct)
println(json)
sharedPreferences.edit().putString("cart_products",json).apply()
}
fun getAllProducts(): ArrayList<Product?> {
sharedPreferences=context.getSharedPreferences(TAG,Context.MODE_PRIVATE)
val listType =
object : TypeToken<List<Product?>?>() {}.type
var productsItemList:ArrayList<Product?> = ArrayList();
val json=sharedPreferences.getString("cart_products",null)
if (json !=null){
var gson=Gson()
productsItemList=gson.fromJson(json,listType)
}
return productsItemList
}

Okay, so you need to:
1)input some word in EditText
2) show it in ListView
3) save it to preferences
right?
I think you must do next steps:
Create private ArrayList<String> list = new ArrayList();
When you input something in EditText and clicked on button, call list.add(editName.getText.toString()); and then call saveFile and save list.toString();
When you need to load file, create function
private void loadFile() {
SharedPreferences sharedPref = getSharedPreferences(FileName,Context.MODE_PRIVATE);
String string = sharedPref.getString("name", "");
ArrayList<String> newList = new ArrayList<String>(Arrays.asList(string.split(", ")));
}
Load in adapter your newList.

How to save the data a user inputs into the device's local internal storage?

I'm developing a Grade/GPA Calculator app on Android during my free time. What the app basically does until now is let the user add Semesters in the Main Activity and when the user clicks on a certain Semester the user is redirected to another Activity where the user can add new Courses for that specific semester. The problem I'm having is that when the user hits on the back button to go to to the Main Activity where the Semesters are located the courses that were added in that semester are erased. The same happens when I go to the phone's homepage and re-launch the app, everything that the user had created has been deleted.
I'm pretty sure my problem is that I'm not saving the data that the user creates to the phone's storage/app's storage, but I can't seem to figure out on how to do this. If anyone can point me in the right direction I would appreciate it. Thanks!
This is my MainActivity class's code: (My MainActivity is where Semesters are added)
package com.example.gradecalculator;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import java.util.ArrayList;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
// Private Fields
private Dialog d;
private EditText semesterName;
private ListView semesterListView;
private ArrayList<String> semesterArray = new ArrayList<String>();
private SemesterAdapter customSemesterAdapter;
private ArrayList<Semester> mySemesters = new ArrayList<>();
private ArrayList<String> semesterBackgrounds = new ArrayList<String>();
private String getSemesterName;
private int randomBackground[] = new int[7];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Initiating toolbar
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Making a new dialog
d = new Dialog(this);
// Initializing variables
semesterName = (EditText) d.findViewById(R.id.editTextSemesterName);
semesterListView = (ListView) findViewById(R.id.semesterList);
// Calling the removeSemesters() method
removeSemesters();
// Adding backgrounds to the backgrounds ArrayList
semesterBackgrounds.add("orange_background");
semesterBackgrounds.add("green_background");
semesterBackgrounds.add("aqua_background");
semesterBackgrounds.add("blue_background");
semesterBackgrounds.add("pink_background");
semesterBackgrounds.add("purple_background");
semesterBackgrounds.add("red_background");
semesterBackgrounds.add("yellow_background");
}
// Creating a custom Menu
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.top_menu, menu);
return true;
}
// Buttons in the custom Menu
#Override
public boolean onOptionsItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.editButton:
Toast.makeText(this, "Delete the desired Semesters by clicking on the trash button located to the right of each Semester", Toast.LENGTH_LONG).show();
return true;
}
return super.onOptionsItemSelected(item);
}
// When user clicks on "+New Semester" button open a popup where the user is prompted to
// type in the Semester Name and when "Done" is clicked the new semester appears in the Main
// Activity
public void newSemesterPopup(View v) {
TextView closePopup;
ImageButton doneButton;
d.setContentView(R.layout.new_semester_popup);
semesterName = (EditText) d.findViewById(R.id.editTextSemesterName);
semesterListView = (ListView) findViewById(R.id.semesterList);
doneButton = (ImageButton) d.findViewById(R.id.doneButton);
doneButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
addSemesters();
}
});
closePopup = (TextView) d.findViewById(R.id.exitButton);
closePopup.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
d.dismiss();
}
});
d.show();
}
// Adds semesters to Main Activity
public void addSemesters() {
getSemesterName = semesterName.getText().toString();
if (semesterArray.contains(getSemesterName)) {
Toast.makeText(getBaseContext(), "Semester Name Already Exists", Toast.LENGTH_SHORT).show();
} else if (getSemesterName == null || getSemesterName.trim().equals("")) {
Toast.makeText(getBaseContext(), "Cannot Add Empty Semester Name", Toast.LENGTH_SHORT).show();
} else {
semesterArray.add(getSemesterName);
mySemesters.add(new Semester(getSemesterName, semesterBackgrounds.get(new Random().nextInt(randomBackground.length))));
customSemesterAdapter = new SemesterAdapter(getApplicationContext(), R.layout.semester_row, mySemesters);
semesterListView.setAdapter(customSemesterAdapter);
d.dismiss();
}
}
// Removes unwanted semesters from Main Activity
public void removeSemesters() {
semesterListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
AlertDialog.Builder deleteAlert = new AlertDialog.Builder(MainActivity.this);
deleteAlert.setTitle("Semester Deletion Process");
deleteAlert.setMessage("Are you sure you want to delete the selected Semesters?");
deleteAlert.setNegativeButton("No! Cancel", null);
deleteAlert.setPositiveButton("Yes! Delete", new AlertDialog.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
customSemesterAdapter.remove(customSemesterAdapter.getItem(position));
semesterArray.remove(position);
customSemesterAdapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "Semester Deleted Successfully.", Toast.LENGTH_SHORT).show();
}
});
deleteAlert.show();
return false;
}
});
openSemestersActivity();
}
// Open the SemesterActivity and uses .putExtra to pass data to the SemesterActivity to tell it what semester to render
// data accordingly
public void openSemestersActivity() {
final Intent semester = new Intent(this, SemesterActivity.class);
semesterListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
semester.putExtra("semester", semesterName.getText().toString());
startActivity(semester);
}
});
}
}
This is my SemesterActivity code: (My SemestersActivity is where Courses are added)
package com.example.gradecalculator;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import java.util.ArrayList;
import java.util.Random;
public class SemesterActivity extends AppCompatActivity {
// Private Fields
private Dialog d;
private EditText courseName;
private EditText courseCode;
private EditText courseCredits;
private ListView courseListView;
private ArrayList<String> courseArray = new ArrayList<String>();
private CourseAdapter customCourseAdapter;
private ArrayList<Course> myCourses = new ArrayList<>();
private ArrayList<String> coursesBackgrounds = new ArrayList<String>();
private String getCourseName;
private String getCourseCode;
private String getCourseCredits;
private int randomBackground[] = new int[7];
private TextView courseNameView;
private TextView courseCodeView;
private TextView courseCreditsView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_semester);
d = new Dialog(this);
courseNameView = (TextView) d.findViewById(R.id.editTextCourseName);
courseCodeView = (TextView) d.findViewById(R.id.editTextCourseCode);
courseCreditsView = (TextView) d.findViewById(R.id.editTextCourseCredits);
courseListView = (ListView) findViewById(R.id.coursesList);
// Retrieving the Extra and determining the semester we want to load
Intent myIntent = getIntent();
String semester = myIntent.getStringExtra("semester");
removeCourses();
// Initiating toolbar
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Adding backgrounds to the backgrounds ArrayList
coursesBackgrounds.add("orange_background_big");
coursesBackgrounds.add("green_background_big");
coursesBackgrounds.add("aqua_background_big");
coursesBackgrounds.add("blue_background_big");
coursesBackgrounds.add("pink_background_big");
coursesBackgrounds.add("purple_background_big");
coursesBackgrounds.add("red_background_big");
coursesBackgrounds.add("yellow_background_big");
}
// Creating a custom Menu
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.top_menu, menu);
return true;
}
// Buttons in the custom Menu
#Override
public boolean onOptionsItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.editButton:
Toast.makeText(this, "Delete the desired Courses by clicking on the trash button located to the right of each Semester", Toast.LENGTH_LONG).show();
return true;
}
return super.onOptionsItemSelected(item);
}
// New course popup
public void newCoursePopup(View v) {
TextView closePopup;
ImageButton doneButton;
d.setContentView(R.layout.new_course_popup);
courseName = (EditText) d.findViewById(R.id.editTextCourseName);
courseCode = (EditText) d.findViewById(R.id.editTextCourseCode);
courseCredits = (EditText) d.findViewById(R.id.editTextCourseCredits);
doneButton = (ImageButton) d.findViewById(R.id.doneButton);
doneButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
addCourses();
}
});
closePopup = (TextView) d.findViewById(R.id.exitButton);
closePopup.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
d.dismiss();
}
});
d.show();
}
// Adding courses to the Semester
public void addCourses() {
getCourseName = courseName.getText().toString();
getCourseCode = courseCode.getText().toString();
getCourseCredits = courseCredits.getText().toString();
if(courseArray.contains(getCourseName)) {
Toast.makeText(getBaseContext(), "Course Name Already Exists", Toast.LENGTH_SHORT).show();
}
else if(getCourseName == null || getCourseName.trim().equals("")) {
Toast.makeText(getBaseContext(), "Cannot Add Empty Course Name", Toast.LENGTH_SHORT).show();
}
else {
courseArray.add(getCourseName);
myCourses.add(new Course(getCourseName, getCourseCode, getCourseCredits, coursesBackgrounds.get(new Random().nextInt(randomBackground.length))));
customCourseAdapter = new CourseAdapter(getApplicationContext(), R.layout.course_row, myCourses);
courseListView.setAdapter(customCourseAdapter);
d.dismiss();
}
}
// Removing courses from the Semester
public void removeCourses() {
courseListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
AlertDialog.Builder deleteAlert = new AlertDialog.Builder(SemesterActivity.this);
deleteAlert.setTitle("Course Deletion Process");
deleteAlert.setMessage("Are you sure you want to delete the selected Courses?");
deleteAlert.setNegativeButton("No! Cancel", null);
deleteAlert.setPositiveButton("Yes! Delete", new AlertDialog.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
customCourseAdapter.remove(customCourseAdapter.getItem(position));
courseArray.remove(position);
customCourseAdapter.notifyDataSetInvalidated();
Toast.makeText(SemesterActivity.this, "Course Deleted Successfully", Toast.LENGTH_SHORT).show();
}
});
deleteAlert.show();
return false;
}
});
}
}

There are a couple of databases you can look into; You can use Room or Realm. You can also check out online DBs like Firestore by Firebase. The beauty about having an online db a user(Student) can access their data from a different phone if they lose or replace their current one. A recommended way to go is to have both to cover both scenarios.

Android App can't write data to Firebase database

I'm trying to follow a tutorial from Udacity to build a chat app with Firebase. Though I followed every instructions, I'm having trouble to write data to the firebase realtime database on button press.
App is running perfectly on the simulator. But whenever I hit the send button, no data shows up in the database. Check the screenshot of the app.
App Screenshot
Added the google services json file.
Added all the dependencies that needed and applied google services plugin in the Build.gradle (app) file.
Added google services classpath in the Build.grade (project) file.
Changed the firebase security rules to the test mode.
What am I doing wrong? Please help.
MainActivity.java file looks like this:
package com.google.firebase.udacity.friendlychat;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.Editable;
import android.text.InputFilter;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.ProgressBar;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.DatabaseReference;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
public static final String ANONYMOUS = "anonymous";
public static final int DEFAULT_MSG_LENGTH_LIMIT = 1000;
private ListView mMessageListView;
private MessageAdapter mMessageAdapter;
private ProgressBar mProgressBar;
private ImageButton mPhotoPickerButton;
private EditText mMessageEditText;
private Button mSendButton;
private String mUsername;
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mMessagesDatabaseReference;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mUsername = ANONYMOUS;
mFirebaseDatabase = FirebaseDatabase.getInstance();
mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("messages");
// Initialize references to views
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
mMessageListView = (ListView) findViewById(R.id.messageListView);
mPhotoPickerButton = (ImageButton) findViewById(R.id.photoPickerButton);
mMessageEditText = (EditText) findViewById(R.id.messageEditText);
mSendButton = (Button) findViewById(R.id.sendButton);
// Initialize message ListView and its adapter
List<FriendlyMessage> friendlyMessages = new ArrayList<>();
mMessageAdapter = new MessageAdapter(this, R.layout.item_message, friendlyMessages);
mMessageListView.setAdapter(mMessageAdapter);
// Initialize progress bar
mProgressBar.setVisibility(ProgressBar.INVISIBLE);
// ImagePickerButton shows an image picker to upload a image for a message
mPhotoPickerButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// TODO: Fire an intent to show an image picker
}
});
// Enable Send button when there's text to send
mMessageEditText.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
#Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if (charSequence.toString().trim().length() > 0) {
mSendButton.setEnabled(true);
} else {
mSendButton.setEnabled(false);
}
}
#Override
public void afterTextChanged(Editable editable) {
}
});
mMessageEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(DEFAULT_MSG_LENGTH_LIMIT)});
// Send button sends a message and clears the EditText
mSendButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FriendlyMessage friendlyMessage = new FriendlyMessage(mMessageEditText.getText().toString(), mUsername, null);
// Clear input box
mMessageEditText.setText("");
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return super.onOptionsItemSelected(item);
}
}

Nothing goes into your database because you aren't writing something in it at all. You are creating an object of FriendlyMessage class but you aren't doing something with it. To solve this, write that object to Firebase database using the following lines of code:
mMessagesDatabaseReference.push().setValue(friendlyMessage);
You should place this line of code, right after the declaration of your friendlyMessage object.

// Send button sends a message and clears the EditText
mSendButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FriendlyMessage friendlyMessage = new FriendlyMessage(mMessageEditText.getText().toString(), mUsername, null);
// here you have to write code for save to firebase DB
mMessagesDatabaseReference.push().setValue(friendlyMessage);
// Clear input box
mMessageEditText.setText("");
}
});
after that you have to read data from firebase and add it to your
list.

Working On A Favorite Websites App

Edit: I've made some updates to this ever since I got responses to this thread. Here's the new thread:
I've been making an Android application where you would save your favorite websites. Here is what I got for the code in the file 'MainActivity.java' so far:
package cory.assignment.favoritewebsitesapp;
import java.util.ArrayList;
import java.util.Collections;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;
public class MainActivity extends ListActivity {
private static final String SEARCHES = "searches";
private EditText queryEditText;
private EditText tagEditText;
private SharedPreferences savedSearches;
private ArrayList<String> tags;
private ArrayAdapter<String> adapter;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
queryEditText = (EditText) findViewById(R.id.queryEditText);
tagEditText = (EditText) findViewById(R.id.tagEditText);
savedSearches = getSharedPreferences(SEARCHES, MODE_PRIVATE);
tags = new ArrayList<String>(savedSearches.getAll().keySet());
Collections.sort(tags, String.CASE_INSENSITIVE_ORDER);
adapter = new ArrayAdapter<String>(this, R.layout.list_item, tags);
setListAdapter(adapter);
ImageButton saveButton = (ImageButton) findViewById(R.id.saveButton);
saveButton.setOnClickListener(saveButtonListener);
getListView().setOnItemClickListener(itemClickListener);
getListView().setOnItemLongClickListener(itemLongClickListener);
}
public OnClickListener saveButtonListener = new OnClickListener()
{
#Override
public void onClick(View v)
{
if (queryEditText.getText().length() > 0 && tagEditText.getText().length() > 0)
{
addTaggedSearch(queryEditText.getText().toString(), tagEditText.getText().toString());
queryEditText.setText("");
tagEditText.setText("");
((InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE)).hideSoftInputFromWindow(tagEditText.getWindowToken(), 0);
}
else
{
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setMessage(R.string.missingMessage);
builder.setPositiveButton(R.string.OK, null);
AlertDialog errorDialog = builder.create();
errorDialog.show();
}
}
};
private void addTaggedSearch(String query, String tag)
{
SharedPreferences.Editor preferencesEditor = savedSearches.edit();
preferencesEditor.putString(tag, query);
preferencesEditor.apply();
if (!tags.contains(tags))
{
tags.add(tag);
Collections.sort(tags, String.CASE_INSENSITIVE_ORDER);
adapter.notifyDataSetChanged();
}
}
OnItemClickListener itemClickListener = new OnItemClickListener()
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
String tag = ((TextView) view).getText().toString();
String urlString = getString(R.string.searchURL) + Uri.encode(savedSearches.getString(tag, ""), "UTF-8");
Intent webIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(urlString));
startActivity(webIntent);
}
};
OnItemLongClickListener itemLongClickListener =
new OnItemLongClickListener()
{
#Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
{
final String tag = ((TextView) view).getText().toString();
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle(getString(R.string.shareEditDeleteTitle, tag));
builder.setItems(R.array.dialog_items, new DialogInterface.OnClickListener()
{
#Override
public void onClick(DialogInterface dialog, int which)
{
switch (which)
{
case 0:
shareSearch(tag);
break;
case 1:
tagEditText.setText(tag);
queryEditText.setText(savedSearches.getString(tag, ""));
break;
case 2:
deleteSearch(tag);
break;
}
}
}
);
builder.setNegativeButton(getString(R.string.cancel), new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialog, int id)
{
dialog.cancel();
}
}
);
builder.create().show();
return true;
}
};
private void shareSearch(String tag)
{
String urlString = getString(R.string.searchURL) + Uri.encode(savedSearches.getString(tag, ""), "UTF-8");
Intent shareIntent = new Intent();
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.shareSubject));
shareIntent.putExtra(Intent.EXTRA_TEXT, getString(R.string.shareMessage, urlString));
shareIntent.setType("text/plain");
startActivity(Intent.createChooser(shareIntent, getString(R.string.shareSearch)));
}
private void deleteSearch(final String tag)
{
AlertDialog.Builder confirmBuilder = new AlertDialog.Builder(this);
confirmBuilder.setMessage(getString(R.string.confirmMessage, tag));
confirmBuilder.setNegativeButton(getString(R.string.cancel), new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialog, int id)
{
dialog.cancel();
}
}
);
confirmBuilder.setPositiveButton(getString(R.string.delete), new DialogInterface.OnClickListener()
{
public void onClick(DialogInterface dialog, int id)
{
tags.remove(tag);
SharedPreferences.Editor preferencesEditor = savedSearches.edit();
preferencesEditor.remove(tag);
preferencesEditor.apply();
adapter.notifyDataSetChanged();
}
}
);
confirmBuilder.create().show();
}
}
However, I have got the errors for the code with certain lines:
Line 79: OK cannot be resolved or is not a field
Line 146: cancel cannot be resolved or is not a field
Line 177: cancel cannot be resolved or is not a field
Line 186: delete cannot be resolved or is not a field
The link below shows what I have for activity_main.xml:
Click here for the image
What could be wrong with those lines? Something isn't right with those lines as they are related to the info on this page.
I am also using the proram Eclipse Java EE IDE for Web Developers to make this as well in case you wanted to know what program I was using. I'm also using API 18 to work on this as well.
If you want to take a look at the other files, then let me know.

I know that some of them are strings that I need to make for the strings.xml file, but would their values have to be messages like "This file is missing", or would they have to be special integers?
They need to be in res/values/strings.xml, yes.
Those values are compiled into "special integers" for you and are accessible by R.string.xxxxx.
I imagine that solves the majority of the errors saying "cannot be resolved or is not a field".
DialogInterference cannot be resolved to a type
Did you mean DialogInterface?
The method deleteSearch(string) from the type MainActivity refers to the missing type string
Look at this line. What is string?
private void deleteSearch(final string tag)

So upon examination, I found out that the other lines did need strings after all despite what it said about certain R.string codes on this page for 'cancel' and 'OK'. So why did 'cancel' and 'OK' need their own strings in strings.xml?