How do I add data I have keyed in a EditText box into an array to list in another activity?

Question

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

Answer 1

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!

Answer 2

Use StartActivityForResult for AddActivity and return object from here and use in MainActivity. For example see here