Develop Reference

Start activity in another activity in Android

After press SignUp button, Display error : unfortunately app has stopped
LogCat error : java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.lolacupcakes/com.example.lolacupcakes.HomeActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
SignUpActivity: Java Code
public class SignUpActivity extends AppCompatActivity {
EditText emailId, password;
Button btnSignUp;
TextView tvSignIn;
FirebaseAuth mFirebaseAuth;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_signup);
mFirebaseAuth = FirebaseAuth.getInstance();
emailId = findViewById(R.id.emailIDSignUp);
password = findViewById(R.id.pwdIDSignUp);
btnSignUp = findViewById(R.id.btnIDSignUp);
tvSignIn = findViewById(R.id.textView);
btnSignUp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String email = emailId.getText().toString();
String pwd = password.getText().toString();
if(email.isEmpty())
{
emailId.setError("Please Enter Email Id");
emailId.requestFocus();
}
else if (pwd.isEmpty())
{
password.setError("Please Enter Email Id");
password.requestFocus();
}
else if (email.isEmpty() && pwd.isEmpty())
{
Toast.makeText(SignUpActivity.this, "Fields are Empty",Toast.LENGTH_SHORT).show();
}
else if (!(email.isEmpty() && pwd.isEmpty()))
{
mFirebaseAuth.createUserWithEmailAndPassword(email,pwd).addOnCompleteListener(SignUpActivity.this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
if (!task.isSuccessful())
{
Toast.makeText(SignUpActivity.this, "SignUp Unsuccessful, Please Try Again",Toast.LENGTH_SHORT).show();
}
else
{
startActivity(new Intent(SignUpActivity.this,HomeActivity.class));
}
}
});
}
else
{
Toast.makeText(SignUpActivity.this, "Error Occurred!",Toast.LENGTH_SHORT).show();
}
}
});
tvSignIn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(SignUpActivity.this, LoginActivity.class);
startActivity(i);
}
});
}
}
SignUpActivity XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SignUpActivity">
<Button
android:id="#+id/btnIDSignUp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="132dp"
android:text="Sign Up" />
<ImageView
android:id="#+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="62dp"
android:src="#drawable/logo_lola" />
<EditText
android:id="#+id/pwdIDSignUp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="206dp"
android:ems="10"
android:hint="Password"
android:inputType="textPassword" />
<EditText
android:id="#+id/emailIDSignUp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="269dp"
android:ems="10"
android:hint="Email"
android:inputType="textEmailAddress" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="87dp"
android:text="Already have an account? Sign in here." />
</RelativeLayout>
HomeActivity Java Code:
public class HomeActivity extends AppCompatActivity {
Button btnlogout;
FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
btnlogout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FirebaseAuth.getInstance().signOut();
Intent intoMain = new Intent(HomeActivity.this, SignUpActivity.class);
startActivity(intoMain);
}
});
}
}
HomeActivityXML:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".HomeActivity">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="Welcome"
android:textSize="50dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0" />
<Button
android:id="#+id/btnLogout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Logout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
tools:layout_editor_absoluteY="424dp" />
</androidx.constraintlayout.widget.ConstraintLayout>

You missed initializing btnlogout. Add this line in HomeActivity onCreate before setting View.OnClickListener
btnlogout = findViewById(R.id.btnLogout);

You need to create btnSignUp object before setonlicklistener for button
btnSignUp = findViewById(R.id.btnLogout);

You need to create the btnSignUp object before setonclicklistener.

ListItem not responding to clickEvents in ArrayAdapter in Android?

"I was trying to create Toast message when user clicks on Description TextView and Like ImageButton. But the list_item is not responding to touch Events "
"I went through many other people answering about changing focus.But none of them are working"
EventsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
final EventsObject mEventsObject = mEventsAdapter.getItem(position);
final String mEventUrl = mEventsObject.geteLink();
Log.e(TAG, "Inside ListVIew");
final boolean status = mEventsObject.hasLiked();
//LikeButton likeButton = view.findViewById(R.id.heart_button);
TextView description = view.findViewById(R.id.eventDesc);
//final TextView likesCountTextView = view.findViewById(R.id.likesCount);
Toast.makeText(MainActivity.this, "Liked", Toast.LENGTH_SHORT).show();
description.setFocusable(false);
description.setFocusableInTouchMode(false);
description.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (!TextUtils.isEmpty(mEventUrl)) {
Intent openLinkInBrowser = new Intent(Intent.ACTION_VIEW);
openLinkInBrowser.setData(Uri.parse(mEventUrl));
startActivity(openLinkInBrowser);
} else {
Toast.makeText(MainActivity.this, "Links are not provided", Toast.LENGTH_SHORT).show();
}
}
});
Button loveBtn = view.findViewById(R.id.loveButton);
loveBtn.setFocusable(false);
loveBtn.setFocusableInTouchMode(false);
loveBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (status) {
Toast.makeText(MainActivity.this, "Liked", Toast.LENGTH_SHORT).show();
mEventsObject.setHeartLiked(true);
} else {
Toast.makeText(MainActivity.this, "Disliked", Toast.LENGTH_SHORT).show();
mEventsObject.setHeartLiked(false);
}
}
});
}
XML for list_item is
?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="8dp"
android:orientation="vertical"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:orientation="horizontal">
<TextView
android:id="#+id/organiser"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="2"
android:paddingLeft="16dp"
android:textAllCaps="true"
android:textColor="#ffffff"
android:textSize="16sp"
android:textStyle="bold"
tools:text="Organiser" />
<TextView
android:id="#+id/dateOfEvent"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="right"
android:textColor="#ffffff"
android:textStyle="bold"
tools:text="12/03/20" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:orientation="horizontal">
<ImageView
android:id="#+id/organiserImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/events_circle"
android:padding="16dp"
android:src="#mipmap/ic_launcher"
android:textColor="#ffffff" />
<TextView
android:id="#+id/eventDesc"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="4dp"
android:gravity="fill"
android:textColor="#ffffff"
android:textSize="16sp"
tools:text="#string/test_event_desc" />
</LinearLayout>
<ImageButton
android:id="#+id/loveButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginBottom="8dp"
android:background="#drawable/events_love"
android:scaleType="center"
android:src="#drawable/love" />
<!--
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginTop="0dp">
<com.like.LikeButton
app:icon_type="heart"
app:icon_size="18dp"
android:id="#+id/heart_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
app:circle_start_color="#ff2134"
app:circle_end_color="#000000"
/>
-->
<!--<TextView
android:id="#+id/likesCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
tools:text="10"
android:textColor="#ffffff"/>
</LinearLayout>-->
</LinearLayout>
"I would like to have list_item's responding to click events and showing toast message..
Please Help..
THanks in Advance !!"

It may be because you are trying to perform click inside item click listener of ListView.
You can fix it by creating a custom adapter for listview. Customer ListView Adapter
After creating this custom adapter you can get the reference of description and loveBtn and perform click operation on this.
Your adapter's getView() code will be like this-
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView==null) {
LayoutInflater layoutInflater = LayoutInflater.from(context);
convertView=layoutInflater.inflate(R.layout.list_row, null);
TextView description=convertView.findViewById(R.id.eventDesc);
Button loveBtn=convertView.findViewById(R.id.loveButton);
}
description.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (!TextUtils.isEmpty(mEventUrl)) {
Intent openLinkInBrowser = new Intent(Intent.ACTION_VIEW);
openLinkInBrowser.setData(Uri.parse(mEventUrl));
startActivity(openLinkInBrowser);
} else {
Toast.makeText(MainActivity.this, "Links are not provided", Toast.LENGTH_SHORT).show();
}
}
});
loveBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (status) {
Toast.makeText(MainActivity.this, "Liked", Toast.LENGTH_SHORT).show();
mEventsObject.setHeartLiked(true);
} else {
Toast.makeText(MainActivity.this, "Disliked", Toast.LENGTH_SHORT).show();
mEventsObject.setHeartLiked(false);
}
}
});
return convertView;
}

Limit a listview to 25 items

I am displaying a listview programmiclly using the following codes:
Below is how the listview is displayed programmatically:
messagesList = (ListView) findViewById(R.id.listMessages);
messageAdapter = new MessageAdapter(this);
I would want to limit the list to 25 items, and where it is not infinite.
Below is the layout.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/white_wallpaper"
>
<ListView
android:id="#+id/listMessages"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_above="#+id/divider"
android:divider="#null"
android:dividerHeight="0dp"
android:inputType="text|textNoSuggestions"
android:padding="0dip"
android:stackFromBottom="true"
android:transcriptMode="alwaysScroll"
tools:listitem="#layout/message_left" />
<RelativeLayout
android:id="#+id/divider"
android:layout_width="fill_parent"
android:layout_height="1dip"
android:background="#color/off_white"
android:layout_above="#+id/relSendMessage" />
<RelativeLayout
android:id="#+id/relSendMessage"
android:layout_width="wrap_content"
android:layout_height="48dp"
android:background="#ddd"
android:paddingLeft="10dp"
android:layout_alignParentBottom="true">
<EditText
android:id="#+id/messageBodyField"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignBottom="#+id/sendButton"
android:layout_alignTop="#+id/sendButton"
android:layout_marginBottom="-4dp"
android:layout_marginRight="10dp"
android:inputType="text|textNoSuggestions"
android:layout_toLeftOf="#+id/sendButton"
android:background="#android:color/white"
android:hint="#string/message_elipses"
android:textColor="#000000"
android:textColorLink="#adefda"
android:textSize="14sp" />
<Button
android:id="#+id/sendButton"
android:layout_width="72dp"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_margin="4dp"
android:background="#drawable/button_send" />
</RelativeLayout>
<Button
android:id="#+id/iSchedule"
android:layout_width="120dp"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:alpha="0.7"
android:background="#C11B17"
android:text="Schedule"
android:textColor="#f2f2f2"
android:textSize="20sp"
android:textStyle="bold"
android:typeface="serif" />
</RelativeLayout>
I have been suggested the following, but I am not sure how to integrate it within the above code:
#Override
public int getCount() {
return 25;
}
Thanks in advance, and for any clarification, let me know.
Update
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.messaging);
feedBack = new FeedbackDialog(this, "ID");
final TextView iSchedule = (TextView) this.findViewById(R.id.iSchedule);
iSchedule.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
MessagingActivity1.this.startActivity(new Intent(MessagingActivity1.this, ScheduleMatchOptionActivity.class));
}
});
Parse.initialize(this, "ID", "ID");
bindService(new Intent(this, MessageService.class), serviceConnection,
BIND_AUTO_CREATE);
Intent intent = getIntent();
recipientId = intent.getStringExtra("RECIPIENT_ID");
currentUserId = ParseUser.getCurrentUser().getObjectId();
messageAdapter = new MessageAdapter(this);
#Override
public int getCount() {
messagesList.setAdapter(messageAdapter);
return 25;
}
messagesList = (ListView) findViewById(R.id.listMessages);
populateMessageHistory();
messageBodyField = (EditText) findViewById(R.id.messageBodyField);
findViewById(R.id.sendButton).setOnClickListener(
new View.OnClickListener() {
#Override
public void onClick(View view) {
sendMessage();
}
});
}
However, I receive the following error
in the live #override it says Syntax error on token(s), misplaced construct(s)
in the public int get count "Syntax error on token(s), misplaced construct(s)"
In the return 25 - Void methods cannot return a value

You want to use that code (or similar) to override the default getCount method in ListAdapter: http://developer.android.com/reference/android/widget/ListAdapter.html
You can check an example in: http://www.vogella.com/tutorials/AndroidListView/article.html#listview_listviewexample

Hey you want to get list with limit, you have two option
1. You set array list size,
2. You can set, when you get data put for loop and set limit

click on listView subItem

I'm trying to click on row in list view but my code only works when i pressed between two rows
you can see this :
http://www.screencast.com/t/2vei8yOQh
note in rep.xml i using table layout and inside it rowTable
i uses this code :
public class LastDaysActivity extends ListActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_last_days);
final Button newFourm = (Button) findViewById(R.id.button1);
LastDaysAdapter adapter = new LastDaysAdapter(this, getDates(),
getApplicationContext(), getBusID());
setListAdapter(adapter);
newFourm.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(LastDaysActivity.this,
TabHostActivity.class);
startActivity(i);
}
});
}
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
TextView myView = (TextView) v.findViewById(R.id.textView2);
String text = myView.getText().toString();
Toast.makeText(this, text + " selected", Toast.LENGTH_LONG).show();
}
edit xml :
<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/TableLayout1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TableRow
android:id="#+id/TableRow05"
android:layout_width="fill_parent"
android:layout_height="27dp"
android:layout_marginTop="4dp"
android:background="#drawable/trans01" >
<TextView
android:id="#+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="رقم اللوحة" />
<TextView
android:id="#+id/TextView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="200dp"
android:text="التاريخ"
android:textSize="12sp" />
</TableRow>
</TableLayout>

Get values from Dynamic list

Good day everyone,
I'm learning Android development and I try to build some dynamic lists for my application. And I'm stuck... like for 4 hours already.
I have two layouts:
1. main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="#+id/action_buttons"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:gravity="center"
>
<Button
android:id="#+id/button_count"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_calculate" />
<Button
android:id="#+id/button_add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#+id/button_count"
android:text="#string/button_add" />
</LinearLayout>
<ScrollView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/action_buttons"
>
<LinearLayout
android:id="#+id/action_list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
</LinearLayout>
</ScrollView>
</RelativeLayout>
action_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/action_list_item_root"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<EditText
android:id="#+id/action_list_item_edittext_drinkName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/action_list_item_button_remove"
android:layout_alignParentTop="true"
android:layout_toRightOf="#+id/action_list_item_title"
android:padding="10dp" />
<EditText
android:id="#+id/action_list_item_edittext_drinkPercent"
android:text="40"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_toLeftOf="#+id/action_list_item_edittext_drinkAmount"
android:inputType="number"
android:padding="10dp"/>
<EditText
android:id="#+id/action_list_item_edittext_drinkAmount"
android:text="0.0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_toLeftOf="#+id/action_list_item_button_remove"
android:layout_alignBottom="#+id/action_list_item_button_remove"
android:inputType="numberDecimal"
android:width="50dp"
android:padding="10dp" />
<Button
android:id="#+id/action_list_item_button_remove"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:text="#string/action_list_item_button_remove" />
And code that creates dynamic list:
public class MainActivity extends Activity {
LinearLayout actionList = null;
private Button btnAdd;
private Button btnCalculate;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initActivityElements();
}
private void initActivityElements() {
initAddButton();
initCalculateButton();
}
private void initCalculateButton() {
btnCalculate = (Button) findViewById(R.id.button_count);
btnCalculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
TextView amount = (TextView) findViewById(R.id.action_list_item_edittext_drinkAmount);
//this retrives TextView value from first list
Toast.makeText(getApplicationContext(), amount.getText().toString(),
Toast.LENGTH_SHORT)
.show();
}
});
}
private void initAddButton() {
actionList = (LinearLayout) findViewById(R.id.action_list);
btnAdd = (Button) findViewById(R.id.button_add);
btnAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
RelativeLayout listItem = (RelativeLayout) View.inflate(
MainActivity.this, R.layout.action_list_item, null);
TextView name = (TextView) listItem
.findViewById(R.id.action_list_item_edittext_drinkName);
name.setText("Here is the Title " + actionList.getChildCount());
listItem.findViewById(R.id.action_list_item_button_remove)
.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
actionList.removeView((View) v.getParent());
}
});
actionList.addView(listItem);
}
});
}
My problem is that I need to get all data from TextView boxes (Amount, Percent), but I can retrive that data only from first item of a list (look at onClickListener for btnCalculate) and can't figure out how to do it, but tried to add 'unique ids' for view (but that brakes layout, badly), tried setting Tags but again with no luck.
Maybe anyone can give a tip? I bet there is some easy way to do it, but I'm failing to find it and google is no help here.
Thanks

I'm not really sure what exactly you are trying to do but it sounds like you are trying to take in information and populate it into a view. I would recommend having a static text box that takes in your information and builds that into a listview. A good example of how to do that is located here http://developer.android.com/resources/tutorials/notepad/notepad-ex1.html.