Develop Reference

Android Studio - Passing variable with intent add extra, ends up with null

after fixing the null pointer exception of a previous question, (Not sure if posting a different question for the same code is okay, do let me know if it is not) I've come across a new problem. When I try passing the date variable from this first activity to another, it is always empty. I've also tried just setting a public getter or the variable and it is also empty. However, using a toast to check within the class shows that the variable does indeed contain the date. I am trying to pass the date class to be added into a database by the other classes in the application package. Any help would be much appreciated.
CalendarActivity.java
package com.example.zaphk.studenthelperapplication3.calendar;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.CalendarView;
import android.widget.Toast;
import com.example.zaphk.studenthelperapplication3.R;
public class CalendarActivity extends AppCompatActivity {
public static final String EXTRA_TEXT = "com.example.zaphk.studenthelperapplication3";
private static final String TAG = "CalendarActivity";
private CalendarView mCalendarView;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calendar_layout);
mCalendarView = (CalendarView) findViewById(R.id.calendarView);
mCalendarView.setOnDateChangeListener(new CalendarView.OnDateChangeListener() {
#Override
public void onSelectedDayChange(CalendarView CalendarView, int year, int month, int dayOfMonth) {
String date = year + "/" + month + "/"+ dayOfMonth ;
Log.d(TAG, "onSelectedDayChange: yyyy/mm/dd:" + date);
Intent intent = new Intent(CalendarActivity.this,CalendarEvent.class);
intent.putExtra(Intent.EXTRA_TEXT,date);
startActivity(intent);
Toast.makeText(CalendarActivity.this,date,Toast.LENGTH_SHORT).show();
}
});
}
}
The class I am trying to receive it from : CalendarEvent.java
package com.example.zaphk.studenthelperapplication3.calendar;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
import com.example.zaphk.studenthelperapplication3.calendar.database.Calendar;
import com.example.zaphk.studenthelperapplication3.calendar.database.CalendarAdapter;
import com.example.zaphk.studenthelperapplication3.calendar.database.Calendar_DbHelper;
import com.example.zaphk.studenthelperapplication3.utils.MyDividerItemDecoration;
import com.example.zaphk.studenthelperapplication3.utils.RecyclerTouchListener;
import com.example.zaphk.studenthelperapplication3.R;
public class CalendarEvent extends AppCompatActivity {
private CalendarAdapter mAdapter;
private List<Calendar> notesList = new ArrayList<>();
private CoordinatorLayout coordinatorLayout;
private RecyclerView recyclerView;
private TextView noNotesView;
Intent intent = getIntent();
public String date;
private Calendar_DbHelper db;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
intent = getIntent();
date = intent.getStringExtra(CalendarActivity.EXTRA_TEXT);
setContentView(R.layout.activity_notes);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
coordinatorLayout = findViewById(R.id.coordinator_layout);
recyclerView = findViewById(R.id.recycler_view);
noNotesView = findViewById(R.id.empty_notes_view);
db = new Calendar_DbHelper(this);
notesList.addAll(db.getAllNotes());
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
showNoteDialog(false, null, -1);
}
});
mAdapter = new CalendarAdapter(this, notesList);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.addItemDecoration(new MyDividerItemDecoration(this, LinearLayoutManager.VERTICAL, 16));
recyclerView.setAdapter(mAdapter);
toggleEmptyNotes();
/**
* On long press on RecyclerView item, open alert dialog
* with options to choose
* Edit and Delete
* */
recyclerView.addOnItemTouchListener(new RecyclerTouchListener(this,
recyclerView, new RecyclerTouchListener.ClickListener() {
#Override
public void onClick(View view, final int position) {
}
#Override
public void onLongClick(View view, int position) {
showActionsDialog(position);
}
}));
}
/**
* Inserting new note in db
* and refreshing the list
*/
private void createNote(String note) {
// inserting note in db and getting
// newly inserted note id
long id = db.insertNote(note);
// get the newly inserted note from db
Calendar n = db.getNote(id);
if (n != null) {
// adding new note to array list at 0 position
notesList.add(0, n);
// refreshing the list
mAdapter.notifyDataSetChanged();
toggleEmptyNotes();
}
}
/**
* Updating note in db and updating
* item in the list by its position
*/
private void updateNote(String note, int position) {
Calendar n = notesList.get(position);
// updating note text
n.setNote(note);
// updating note in db
db.updateNote(n);
// refreshing the list
notesList.set(position, n);
mAdapter.notifyItemChanged(position);
toggleEmptyNotes();
}
/**
* Deleting note from SQLite and removing the
* item from the list by its position
*/
private void deleteNote(int position) {
// deleting the note from db
db.deleteNote(notesList.get(position));
// removing the note from the list
notesList.remove(position);
mAdapter.notifyItemRemoved(position);
toggleEmptyNotes();
}
/**
* Opens dialog with Edit - Delete options
* Edit - 0
* Delete - 0
*/
private void showActionsDialog(final int position) {
CharSequence colors[] = new CharSequence[]{"Edit", "Delete"};
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Choose option");
builder.setItems(colors, new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
if (which == 0) {
showNoteDialog(true, notesList.get(position), position);
} else {
deleteNote(position);
}
}
});
builder.show();
}
/**
* Shows alert dialog with EditText options to enter / edit
* a note.
* when shouldUpdate=true, it automatically displays old note and changes the
* button text to UPDATE
*/
private void showNoteDialog(final boolean shouldUpdate, final Calendar note, final int position) {
LayoutInflater layoutInflaterAndroid = LayoutInflater.from(getApplicationContext());
View view = layoutInflaterAndroid.inflate(R.layout.note_dialog, null);
AlertDialog.Builder alertDialogBuilderUserInput = new AlertDialog.Builder(CalendarEvent.this);
alertDialogBuilderUserInput.setView(view);
final EditText inputNote = view.findViewById(R.id.note);
TextView dialogTitle = view.findViewById(R.id.dialog_title);
dialogTitle.setText(!shouldUpdate ? getString(R.string.lbl_new_note_title) : getString(R.string.lbl_edit_note_title));
if (shouldUpdate && note != null) {
inputNote.setText(note.getNote());
}
alertDialogBuilderUserInput
.setCancelable(false)
.setPositiveButton(shouldUpdate ? "update" : "save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogBox, int id) {
}
})
.setNegativeButton("cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogBox, int id) {
dialogBox.cancel();
}
});
final AlertDialog alertDialog = alertDialogBuilderUserInput.create();
alertDialog.show();
alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Show toast message when no text is entered
if (TextUtils.isEmpty(inputNote.getText().toString())) {
Toast.makeText(CalendarEvent.this, "Enter note!", Toast.LENGTH_SHORT).show();
return;
} else {
alertDialog.dismiss();
}
// check if user updating note
if (shouldUpdate && note != null) {
// update note by it's id
updateNote(inputNote.getText().toString(), position);
} else {
// create new note
createNote(inputNote.getText().toString());
}
}
});
}
/**
* Toggling list and empty notes view
*/
private void toggleEmptyNotes() {
// you can check notesList.size() > 0
if (db.getNotesCount() > 0) {
noNotesView.setVisibility(View.GONE);
} else {
noNotesView.setVisibility(View.VISIBLE);
}
}
public String getDate(){
return date;
}
}

You are using wrong key while passing data between activity.
Replace below line,
intent.putExtra(Intent.EXTRA_TEXT,date);
With this one,
intent.putExtra(CalendarActivity.EXTRA_TEXT,date);

You use the key of Intent.EXTRA_TEXT.
intent.putExtra(Intent.EXTRA_TEXT,date)
But you use the other key to receive. It's not the same key.
intent.getStringExtra(CalendarActivity.EXTRA_TEXT);

As per I know (Not pretty sure)
Intent.EXTRA_TEXT
is used for implicit intents.
For explicit (i.e.Activity to Activity)
Do as below
Intent intent = new Intent(CalendarActivity.this,CalendarEvent.class);
intent.putExtra("DATE",date);
startActivity(intent);
To receive
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_notes);
intent = getIntent();
String date = intent.getStringExtra("DATE");
}
Where "DATE" is String KEY.

I would say that CalendarActivity.EXTRA_TEXT is probably empty because you have not imported that class in to CalendarEvent.java
import com.example.zaphk.studenthelperapplication3.calendar.CalendarActivity; in CalendarEvent.java
and as other people have said the put and get on the Intent need to be the the same String value.

How to run this page just once after installing the page

I want this code to run just once after installing the app.
Page 1 has a button and after clicking it, the user will be directed to page 2.
Page 2 is the disclaimer page and after checkboxes are marked and agree button is clicked, the user is directed to the home page.
When the user clicks for the second time, this disclaimer page should not open again.
I tried to modify my code for it, but I couldn't because of the button as I'm not sure how to use it.
Page 1
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
public Button btn_Shap;
public void first(){
btn_Shap = (Button)findViewById(R.id.btn_Shap);
btn_Shap.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent btn = new Intent(MainActivity.this, disclaimer.class);
startActivity(btn);
}
});
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
first();
}
}
Page 2
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class disclaimer extends AppCompatActivity {
public Button button2;
public Button button1;
public void second(){
button2 = (Button)findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent btn = new Intent(disclaimer.this, home.class);
startActivity(btn);
}
});
}
public void first(){
button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent btn = new Intent(disclaimer.this, MainActivity.class);
startActivity(btn);
}
});
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_disclaimer);
second();
first();
}
}

Inside the desclaimer page store a boolean value using shared preference and check it before open the desclaimer page. like this
Inside the Desclaimer page
SharedPreferences settings = getSharedPreferences("prefs", 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("firstRun", false);
editor.commit();
Before open the desclaimer page
SharedPreferences settings = getSharedPreferences("prefs", 0);
boolean firstRun = settings.getBoolean("firstRun", true);
if ( firstRun )
{
//Open desclaimer
}else{
//Do not open desclaimer
}

remember username and password checkbox

I have this Javascript code for login in my app. it working fine but how can I add a checkbox for remember username and password to this code to my project? Is there some one out there that can help me? Thanks for all help
package no.vfk.vfkhakkespettboka;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Login_backup extends AppCompatActivity {
private EditText Name;
private EditText Password;
private TextView Info;
private Button Login;
private int counter = 6;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
Name = (EditText)findViewById(R.id.etName);
Password = (EditText)findViewById(R.id.etPassword);
Info = (TextView)findViewById(R.id.tvInfo);
Login = (Button)findViewById(R.id.btnLogin);
Info.setText("No attempt remains: 6");
Login.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
validate(Name.getText().toString(), Password.getText().toString());
}
});
}
private void validate(String userName, String userPassword){
if((userName.equals("test")) && (userPassword.equals("test123"))){
Intent intent = new Intent(Login_backup.this, Home.class);
startActivity(intent);
}else{
counter--;
Info.setText("No attempt remains: " + String.valueOf(counter));
if(counter == 0){
Login.setEnabled(false);
}
}
}
}

Submit button not validating

I am trying to get a submit button to take me to the next page when the input is milk. Here's what I've tried so far
package com.example.ephraimcohen.prestwichlanguageschool;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class activitytwomilk2 extends AppCompatActivity {
private EditText Word;
private TextView TryAgain;
private Button Submit;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activitytwomilk2);
Word = (EditText)findViewById(R.id.etword);
TryAgain = (TextView)findViewById(R.id.tvtryagian);
Submit = (Button) findViewById(R.id.btnsubmit);
TryAgain.setText(" ");
Submit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
validate(Word.getText().toString());
}
});
}
private void validate(String userWord){
if((userWord.equals ("milk"))){
Intent intent = new Intent(activitytwomilk2.this, activitytwomilkcorrect.class);
startActivity(intent);
}else{
TryAgain.setText(" " + "Try again");
}
}`
Under that, there is another button which just goes to the home screen. That button is working properly and taking me to the homepage.

Try to use == instead of equals in your condition
if(userWord=="milk"){
Intent intent = new Intent(activitytwomilk2.this, activitytwomilkcorrect.class);
startActivity(intent);
}else{
TryAgain.setText(" " + "Try again");
}
}`

using custom_dialog.dismiss() force closes app

i have just started with android but have done some c# which seems very similar to java
in short, the problem lies in the closeDialog method
I am not very familiar with view/viewgroup so please dont bombard me with incorrect usage of objects, etc.
in short, i am creating a simple app which i hope to improve on (it is basically the start of a huge project)
the _showhint dialog opens fine, and shows the "hint" as expected, but the closeDialog force closes the app, I have no idea why
package com.example.app;
import android.app.Activity;
import android.app.Dialog;
import android.net.Uri;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.webkit.ValueCallback;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends ActionBarActivity {
private WebView webView;
final Activity activity = this;
public Uri imageUri;
private ValueCallback<Uri> mUploadMessage;
private Uri mCapturedImageImageURI = null;
private TextView lblAnswer, lblWelcome;
private EditText edtInput;
public TextView showText ;
public Button btnShowHint, btnCalculate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edtInput = (EditText) findViewById(R.id.edtInput) ;
lblWelcome = (TextView) findViewById(R.id.lblWelcome) ;
lblAnswer = (TextView) findViewById(R.id.lblAnswer) ;
btnShowHint = (Button) findViewById(R.id.btnHelp);
btnCalculate = (Button) findViewById(R.id.btnShow) ;
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
public void calculate(View vw)
{
String [] arrEditStore = new String[edtInput.length()] ;
String arrOperators [] = {"+", "-", "*", "/", "(", ")"} ;
}
public void _showhint(View vw)
{
final Dialog showHintDialog = new Dialog(activity);
showHintDialog.setContentView(R.layout.custom_dialog);
showHintDialog.setTitle("How to enter data");
showHintDialog.show();
}
public void closeDialog(View vw)
{
final Dialog dialog = new Dialog(this) ;
Button btnClose = (Button) dialog.findViewById(R.id.button) ;
btnClose.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dialog.dismiss();
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
EDIT: ADDED "this" to final Dialog dialog = new Dialog(this)

I have discovered what has caused the problem
GIVEN CODE:
public void _showhint(View vw)
{
final Dialog showHintDialog = new Dialog(activity);
showHintDialog.setContentView(R.layout.custom_dialog);
showHintDialog.setTitle("How to enter data");
showHintDialog.show();
}
public void closeDialog(View vw)
{
final Dialog dialog = new Dialog(this) ;
Button btnClose = (Button) dialog.findViewById(R.id.button) ;
btnClose.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
dialog.dismiss();
}
});
}
SOULTION
first, I moved the decleration of the btnClose to the top
public Button btnShowHint, btnCalculate, btnClose;
then in the design view, removed the link of the button Close onclick method refering to closeDialog.
Afterwards, removing the closeDialog method completely, and also moving some of that code to the _showHint method
it also makes logical sense, thanks to #Mike M. who commented on the post, helped me reason it out, since I say, THIS button must close the dialog but in the method of this button, I am assigning it to be used by itself, which doesn't make logical sense at all, here is the changed code and it works
CHANGED CODE:
public void _showhint(View vw)
{
final Dialog showHintDialog = new Dialog(activity);
showHintDialog.setContentView(R.layout.custom_dialog);
showHintDialog.setTitle("How to enter data");
showHintDialog.show();
btnClose = (Button) showHintDialog.findViewById(R.id.button) ;
btnClose.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
showHintDialog.dismiss();
}
});
}
We all make stupid and unnessasary mistakes at times, some worse than others, but if you find a solution to a problem you have had, maybe somewhere someone has the same issue, so post a solution to your problem, it might help that someone!!!
cheers