Below are the 3 java classes which I am using for my android application development. I would like to add the student data (name and phone number) from the AddActivity to be stored in MainActivity page after clicking "Add". I have researched on this and tried using an array. But I am quite confused on how the logic must be for the code to send the data keyed in AddActivity into the MainActivity page. Can anyone give me a guidance on how to work this out and would really be grateful if you could show me another way rather the way I am trying. I want the data to be stored in a ListView format in the MainActivity after each "Add" I have clicked in the AddActivity page. I do hope that someone will be able to guide me in doing this. Thank you.
MainActivity.java -
https://jsfiddle.net/eb1fprnn/
public class MainActivity extends AppCompatActivity {
ListView listView;
Button addStudent;
ArrayList<Student> students = new ArrayList<Student>();
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
add();
}
public void add() {
Student student;
addStudent = (Button) findViewById(R.id.add);
addStudent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, AddActivity.class);
startActivity(intent);
}
});
}
}
AddActivity.java -
https://jsfiddle.net/40k5mas2/
public class AddActivity extends AppCompatActivity {
EditText name, phone;
Button add;
int FphoneNumber;
String Fname;
ArrayList<Student> students;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = getIntent();
students = (ArrayList<Student>) getIntent().getSerializableExtra("AddNewStudent");
setContentView(R.layout.activity_add);
edit();
addStudent();
}
public void edit() {
name = (EditText) findViewById(R.id.StudentName);
phone = (EditText) findViewById(R.id.phone);
final Button addStudent = (Button) findViewById(R.id.AddStudent);
name.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
addStudent.setEnabled(!name.getText().toString().trim().isEmpty());
Fname = name.getText().toString();
String phoneNumber = phone.getText().toString();
FphoneNumber = Integer.parseInt(phoneNumber);
}
#Override
public void afterTextChanged(Editable s) {
}
});
}
public void addStudent() {
add = (Button) findViewById(R.id.AddStudent);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(AddActivity.this, MainActivity.class);
intent.putExtra("studentName",name.getText().toString() );
intent.putExtra("phoneNumber",phone.getText().toString());
startActivity(intent);
Student student = new Student(Fname, FphoneNumber);
students.add(student);
}
});
}
public void addStudent(){
add = (Button) findViewById(R.id.AddStudent);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(AddActivity.this,Record.class);
startActivity(intent);
}
});
}
Student.java -
https://jsfiddle.net/gy0g7b0s/
public class Student {
String mName;
int mPhoneNumber;
public Student (String name, int number){
mName = name;
mPhoneNumber = number;
};
public String getmName() {
return mName;
}
public String getmName(String newName) {
return (this.mName = newName);
}
public int getmPhoneNumber() {
return this.mPhoneNumber;
}
public int getmPhoneNumber(int newPhoneNumber) {
return (this.mPhoneNumber = newPhoneNumber);
}
#Override
public String toString() {
return String.format("%s\t%f",this.mName, this.mPhoneNumber);
}
[1] : [Image of Main Activity Page] http://imgur.com/a/pMWt4
[2] : [Image of Add Activity Page] http://imgur.com/a/8YvVc
as mentioned above, the correct way would be to use the startActivityForResult method. Check this.
And how to go about it, Damn easy!
Modifying your code:
public void add() {
Student student;
addStudent = (Button) findViewById(R.id.add);
addStudent.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, AddActivity.class);
startActivityForResult(intent,123);
}
});
}
}
and in the same activity (MainActivity) listen for the result
Also would recommend you to use the parceler.org lib for sending objects
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode== Activity.RESULT_OK && requestCode==123){
// perform your list addition operation here and notify the adapter for change
// the returned data comes in 'data' parameter and would recommend you to use parcels.org lib
// for sending parcelable pojo across activities and fragments.
list.add(Parcels.unwrap(data.getParcelableArrayExtra(YOUR_KEY)));
adapter.notifyDataSetChanged();
}
}
And in your AddActivity, when you add just do this.
public void addStudent() {
// add the 'add' button view to the oncreatemethod
// add = (Button) findViewById(R.id.AddStudent);
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Do not restart the activity that opened this activty
// this activity is anyways on top of the MainActivity. Just finish this activty setting the result
// Intent intent = new Intent(AddActivity.this, MainActivity.class);
// intent.putExtra("studentName",name.getText().toString() );
// intent.putExtra("phoneNumber",phone.getText().toString());
// startActivity(intent);
// How to do that?
Student student = new Student(Fname, FphoneNumber);
Intent intent = new Intent();
intent.putExtra(YOUR_KEY, Parcels.wrap(student));
// you can also do it without the parcels lib
// intent.putExtra("studentName",name.getText().toString() );
// intent.putExtra("phoneNumber",phone.getText().toString());
setResult(123,intent); // set the result code. it should be the same one as the one your listening on in MainAcitivty
// then just finish this activity.
finish();
// this calls the onActivtyResultMethod in MainActivity which furtther does the logic
// students.add(student);
}
});
}
That should work! Cheers!
Use StartActivityForResult for AddActivity and return object from here and use in MainActivity. For example see here
Since you store the data in a file, the add activity should just write the data to the file. Then the main activity should always read the file to refresh the list.
I will suggest using a static class if you don't want to use a Database.
Or if you should use a file is just very simple to write into a file when you add and read from it in the next activity.
Just create a Static class like this.
public static class MyStaticClass{
private static ArrayList <Student> mStudents = new ArrayList<Student>()
public static void addStudent(Student theNewStudent){
mSudents.add(theNewStudent);
}
public static List<Student> getStudents(){
return mStudents;
}
}
or with a file:
public static class MyFileClass{
private static String pathFile = "Your path";
public static void addStudent(Student theNewStudent){
File file = new OutputStreamWriter(new FileOutputStream(pathFile,true)); //the true is to append to the file
file.write(/*parse your student as a string*/);
file.close();
}
public static List<Student> getStudents(){
ArrayList<Student> students = new ArrayList<>()
File file = new File(pathFile);
Scanner sc = new Scanner(file);
while (sc.hasNextLine()) {
String line = sc.nextLine();
//parse your line to a student object
students.add(yourNewStudent);
}
sc.close();
return students;
}
}
Just call the add student and the get students in the proper class as follows.
MyStaticClass.addStudent(student);
or
MyFileClass.addStudent(student);
Hope it helps.
In your onclick listener:
public void onClick(View v) {
Intent intent = new Intent(AddActivity.this, MainActivity.class);
Student student = new Student(Fname, FphoneNumber);
MyStaticClass.addStudent(student); // or the FileClass
startActivity(intent);
}
and i cant see where do you retrieve the list. but just use the getStudents of the class.
Intent yourFirstAct= new Intent(firstAct.this,second.class);
yourFirstAct.putExtra("","");
startActivitForResult(yourFirstAct);
in first Activity,
#Override
public void onAcitivityResult(....){
super();
}
in your second activity when you done,
do your stuff whatever you want in second activity. and pass it to mainActivity
Intent yoursecAct= new Intent();
yourSecAct.putExtra("","");
setResult(yourSecAct);
finish();
IF YOU ARE USING IN FRAGMENT
if you do startActivityResult() in fragment means,
your fragment mainActivity must return super() in
public void onAcitivityResult(...){super()}
After getting the details from the student, put the respective details in a bundle and just use intent to go back to the main activity. Then use bundles to extract the data in the main activity.
You can use startActivityForResult for the same. if you haven't found the answer yet then please let me know. I will provide you the code.
Many above answers already defined this thing in a very good way.
This is about communication between Activities. You can use event bus to realize this.
https://github.com/JackZhangqj/EventBus
Then 1. Add event bus dependency to the App's build.grade
compile "de.greenrobot:eventbus:3.0.0
Register and unregister your subscribe in the MainActivity.java
#Override
protected void onStart() {
super.onStart();
EventBus.getDefault().register(this);
}
#Override
protected void onStop() {
super.onStop();
EventBus.getDefault().unregister(this);
}
3.Post event in the AddActivity.java
EventBus.getDefault().post(new Student(name.getText().toString(), phone.getText().toString()));
4.Implement event handling method in MainActivity
//The student is the added student in the AddActivity.java
public void onEventMainThread(Student student) {
}
To kind of expand a little bit on MadScientist's answer, ListView's need adapters in order set the data in it's view. You'll need to define an ArrayAdapter for your list view to communicate with. This will need to go in your MainActivity and will be initialized in the onCreate method. Assuming you want to display both types of information, you'll need to construct your adapter with the built in layout for showing two items via android.R.layout.simple_list_item_2. If you would like to create your own layout, however, you can look up how to do that here.
public class MainActivity extends AppCompatActivity {
Button addStudent;
ArrayAdapter<Student> adapter;
ArrayList<Student> students = new ArrayList<Student>();
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_2, students);
ListView listView = (ListView) findViewById(R.id.listView);
listView.addAdapter(adapter);
add();
}
Call the startActivityForResult(intent, 123) in your Listener to start the new activity. Then, once you have typed in your data, add your items to the intent and call finish() in your AddActivity. Override the onActivityResult in your MainActivity to pull the items off your intent and add them to your list. Finally, notify the adapter of the changes via adapter.notifyDataSetChanged()
I have Preference class extent PreferenceActivity.
I create public static String quality; in Preference.class i add in onCreate
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref);
quality = "QUALITY_HIGH";//initialize
}
and add in Preference.class this method
public void getQuality() {
if (keyquality.equals("480p")) {
quality = "QUALITY_LOW";
//
}
if (keyquality.equals("720p")) {
//
quality = "QUALITY_720P";
}
if (keyquality.equals("1080p")) {
//
quality = "QUALITY_HIGH";
}
}
in another class i create method to get my variable and set settings
private void getqualityvideo() {
/*if (Prefernce.quality == null) {
preferencecamrecoder = CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH);
} else {*/
if (Prefernce.quality.equals("QUALITY_LOW")) {
preferencecamrecoder = CamcorderProfile.get(CamcorderProfile.QUALITY_LOW);
}
if (Prefernce.quality.equals("QUALITY_720P")) {
preferencecamrecoder = CamcorderProfile.get(CamcorderProfile.QUALITY_720P);
}
if (Prefernce.quality.equals("QUALITY_HIGH")) {
preferencecamrecoder = CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH);
}
// }
}
Problem:
when start application
private void startServes() {
btnStart = (ImageView) findViewById(R.id.StartService);
btnStart.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
v.startAnimation(mAnimationImage);
Intent intent = new Intent(MainActivity.this, RecorderService.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startService(intent);
changeCamera
.setEnabled(false);
btnStart.setEnabled(false);
setings.setEnabled(false);
moveTaskToBack(false);
}
});
}
in another class in method
getqualityvideo() error NullPointerException
error in this first line
if (Prefernce.quality.equals("QUALITY_LOW"))
why the quality variable is empty?
The reason is that you're setting Preference.quality in the onCreate method in your Preference class. So what's probably happening is that when you start your application in your other class, Preference.quality is going to be null because it was never initialized to anything. The reason is that the other class has no way to access the onCreate method in your Preference class as of now. onCreate is executed when an activity starts, but that doesn't seem to happen anywhere in your code. A solution could be to initialize public static String quality outside of your onCreate method but still within the Preference class,
public static String quality = "QUALITY_HIGH";
#Override
public void onCreate(Bundle savedInstanceState) {
//insert code here
}
The problem was merely a scope issue.
I'm running through a for-loop and am generating TextViews that should be clickable because I want to start then an intent and pass the url as parameter as well as the source.
So, I've tried this
articleURL[i].setPaintFlags(articleURL[i].getPaintFlags() | Paint.UNDERLINE_TEXT_FLAG);
articleURL[i].setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//System.out.println(articleURL[v.getId()].getText().toString());
System.out.println(v.getId());
}
});
The problem i encounter is that the v.getId() is always 0. And when i use the commented code
System.out.println(articleURL[v.getId()].getText().toString());
I get an exception that says
java.lang.ArrayIndexOutOfBoundsException: length=10; index=-1
I just need the content of the TextView i clicked on. How exactly do i get it? articleURL[i] doesn't work because he doesn't know i then. How can v.getId() always be -1? No matter which one I click?
This here is the complete for-loop
TextView articleURL = new TextView[hashMapSize];
for (int i = 0; i < hashMapSize; i++) {
articleURL[i] = new TextView(getActivity());
articleURL[i].setPaintFlags(articleURL[i].getPaintFlags() | Paint.UNDERLINE_TEXT_FLAG);
articleURL[i].setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
System.out.println(articleURL[v.getId()].getText().toString());
//System.out.println(v.getId());
}
});
}
You actually get the View in the parameter. Just cast it to TextView and call getText()
public void onClick(View v) {
Log.d("text",((TextView) v).getText().toString());
}
Also don't use System.out.println. This is Android, not desktop Java, and coding android is a huge difference to normal Java. You should get a book on Android and read it, otherwise your apps will start crashing pretty soon and you won't have any chance to fix them.
You may try the following:
View.OnClickListener listener = new View.OnClickListener() {
#Override
public void onClick(View v) {
System.out.println(((TextView)v).getText());
}
};
// ... some loop
articleURL[i].setOnClickListener(listener);
If you also want to get index of item, try this:
View.OnClickListener listener = new View.OnClickListener() {
#Override
public void onClick(View v) {
System.out.println(v.getTag());
}
};
// ... some loop
articleURL[i].setTag(i);
articleURL[i].setOnClickListener(listener);
Try this..
use this as globel
TextView articleURL[];
and then initial the articleURL like below
articleURL = new TextView[hashMapSize];
and then if your extends fragement means use below
articleURL[i] = new TextView(getActivity());
extends activity means
articleURL[i] = new TextView(this);
and
System.out.println(((TextView)v).getText().toString());
How can I get the value of a method parameter "myInteger" in this code.
public void myMethod(int myInteger) {
View.OnClickListener myClearHandler = new View.OnClickListener() {
public void onClick(View v) {
//***How can I get the value of "myInteger" here?***
}
};
}
Assuming you're just trying to read it, you just need to make it final:
public void myMethod(final int myInteger) {
View.OnClickListener myClearHandler = new View.OnClickListener() {
public void onClick(View v) {
int foo = myInteger;
}
};
}
In Java, only final parameters and local variables can be accessed within anonymous inner classes.
I am guessing the language should support closures and all you need to do in this case is use the variable myInteger in your onClick listener and you should be fine.. This works in fine in many languages I am not sure about Java though.
public void myMethod(final int myInteger) {
View.OnClickListener myClearHandler = new View.OnClickListener() {
public void onClick(View v) {
int myInteger = myInteger * 100;
}
};
}
AS posted by John Skeet: the final keyword is important here.
You Cannot refer to a non-final variable myInteger inside an inner class
defined in a different method
You might be getting this error, so for that you have to declare it as final like this
final int myInteger
I am developing an android application. Now i have created one function which create custom dialog box and i want this dialog box to display on every activity. So i need to call this function at every activity. But as the syntax of custom dialog (e.g. Dialog d = new Dialog(home.this)).home is the name of the activity where i have created the function so i am not ale to use this function in any other activity. And i haven't use android that much. So give me good example to solve my problem. Here is my code
here is sample code code of using AlertDialog in all activity.
crate one class file like as allmethod.java
and add this code in that class
public static void showAlert(Activity act,String msg)
{
AlertDialog.Builder alert = new AlertDialog.Builder(act);
alert.setMessage(msg).setPositiveButton("OK", new OnClickListener(){
#Override
public void onClick(DialogInterface dialog, int which)
{
}
}).show();
}
and you can use from any class like as
allmethod.showAlert(Activity,"Message");
In your case..
public void SearchDialog(Context ctx){
final Dialog dialog = new Dialog(ctx);
dialog.setContentView(R.layout.dialogsearch);
dialog.setTitle(" Enter The Text to Search");
dialog.setCancelable(true);
final EditText Text = (EditText) dialog.findViewById(R.id.EdText);
Button buttonOK = (Button) dialog.findViewById(R.id.btnOK);
buttonOK.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String SearchText = Text.getText().toString();
prefsPrivate =getSharedPreferences(Login.PREFS_PRIVATE,Context.MODE_PRIVATE);
Editor prefsPrivateEdit=prefsPrivate.edit();
prefsPrivateEdit.putString("Text",SearchText);
prefsPrivateEdit.commit();
Intent i = new Intent(ctx,SearchTask.class);
startActivity(i);
dialog.cancel();
}
});
Button buttonCancel = (Button) dialog.findViewById(R.id.btnCancel);
buttonCancel.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
dialog.cancel();
}
});
dialog.show();
}
Just add a Context parameter to your SearchDialog() constructor.
Make it like this:
public SearchDialog(Context context){
//....
}
You could either define your own Interface and implement for every class, or make the main Activity method static (as long as it wont need to access anything in dynamic objects that aren't method arguments).
final class Uutil {
public void static func() {
}
}
then do it in your classes:
class A {
public void f() {
Uutil.func();
}
}