将数据发送到其他活动后，Intent对象显示为null

Question

I am facing problem while sending data through Intent .

Let's say I have two Activities :

1. Personal Information

2. Documentational Information.

What I am doing: When user fills all the given edit text fields and clicks save I send all the data through intent to the 3rd activity and now user is in the documentational activity, enters data and hits save, and data is transferred to the 3rd Activity.

The problem is in the 3rd Activity : I only get data based on the latest activity - I mean if user first enters personal info and then documentational info, I only get data of doucumentational activity and vice versa.

I am building an app that can get data from the user and show it in a pdf file

personal info activity :

public void getting_data_from_fields_and_sending_on_click_listner () {

        radio_Group_Martial_Status.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, @IdRes int checkedId) {

                RadioButton radioButton = (RadioButton) findViewById(checkedId);
                martial_status = radioButton.getText().toString() ;

            }
        });

        Intent sendingData = new Intent (Personal_Information_Activity.this , Selecting_Activity.class);
        sendingData.putExtra("FirstName" , fullName.getText().toString() );
        sendingData.putExtra("Born" , born.getText().toString() );
        sendingData.putExtra("Nationality" , nationality.getText().toString() );
        sendingData.putExtra("CurrentPlace" , currentPlace.getText().toString() );
        sendingData.putExtra("Address" , address.getText().toString() );
        sendingData.putExtra("PhoneNumber" , phoneNumber.getText().toString() );
        sendingData.putExtra("EmailAddress" , emailAddress.getText().toString() );
        sendingData.putExtra("SelfIntro" , selfIntro.getText().toString() );
        sendingData.putExtra("Day" ,  day.getSelectedItem().toString());
        sendingData.putExtra("Month" , month.getSelectedItem().toString() );
        sendingData.putExtra("Year" , year.getSelectedItem().toString() );
        sendingData.putExtra("MartialStatus" , martial_status);

        startActivity(sendingData);
}

doc info activity

private void getting_data_from_fields_and_sending_on_click_listner() {

        Intent sendingData = new Intent (Documentation_Activity.this , Selecting_Activity.class);

        String passportIssueDate = passportIssueM.getSelectedItem().toString()+"-"+passportIssueY.getSelectedItem().toString();
        String idCardIssueDate = idIssueM.getSelectedItem().toString()+"-"+idIssueY.getSelectedItem().toString();
        String licenceIssueDate = licenceIssueM.getSelectedItem().toString()+"-"+licenceIssueY.getSelectedItem().toString();
        String passportExpiryDate =  passportExpiryM.getSelectedItem().toString()+"-"+passportExpiryY.getSelectedItem().toString();
        String idCardExpiryDate =  idExpiryM.getSelectedItem().toString()+"-"+idExpiryY.getSelectedItem().toString();
        String licenceExpiryDate =  licenceExpiryM.getSelectedItem().toString()+"-"+licenceExpiryY.getSelectedItem().toString();

        sendingData.putExtra("PassportNumeber" , passportNumber.getText().toString());
        sendingData.putExtra("IdCard" , idCardNumber.getText().toString());
        sendingData.putExtra("Licence" , licenceNumebr.getText().toString());

        sendingData.putExtra("PID"  , passportIssueDate);
        sendingData.putExtra("PED"  , passportExpiryDate);
        sendingData.putExtra("IID"  , idCardIssueDate);
        sendingData.putExtra("IED"  , idCardExpiryDate);
        sendingData.putExtra("LID"  , licenceIssueDate);
        sendingData.putExtra("LED"  , licenceExpiryDate);

        startActivity(sendingData);
    }

3rd activity

    public void gettingInfoFromTheDocumentationalInformationActivity() {    

        passportNumber =  getInformation.getStringExtra("PassportNumeber");
        passportIssue =  getInformation.getStringExtra("PID");
        passportExpiry =  getInformation.getStringExtra("PED");
        idNumebr =  getInformation.getStringExtra("IdCard");
        idIssue =  getInformation.getStringExtra("IID");
        idExpiry =  getInformation.getStringExtra("IED");
        licenceNumebr =  getInformation.getStringExtra("Licence");
        licenceIssue =  getInformation.getStringExtra("LID");
        licenceExpiry =  getInformation.getStringExtra("LED");
    }

    public void gettingInfoFromThePersonalInformationActivity() {

        fullName = getInformation.getStringExtra("FirstName");
        born = getInformation.getStringExtra("Born");
        nationality = getInformation.getStringExtra("Nationality");
        currentLocation = getInformation.getStringExtra("CurrentPlace");
        address = getInformation.getStringExtra("Address");
        emailAddress = getInformation.getStringExtra("EmailAddress");
        selfInfo = getInformation.getStringExtra("SelfIntro");
        phoneNumber = getInformation.getStringExtra("PhoneNumber");
        day = getInformation.getStringExtra("Day");
        month = getInformation.getStringExtra("Month");
        year = getInformation.getStringExtra("Year");
        martialStatus = getInformation.getStringExtra("MartialStatus");
    }

    private void createPdf() throws FileNotFoundException, DocumentException 
    {
        Document document = new Document(PageSize.A4);

        String output = Environment.getExternalStorageDirectory()+"/mypdf.pdf";

        PdfWriter.getInstance(document, new FileOutputStream(output));

        document.open();

        document.add(new Paragraph("Name : " +fullName));
        document.add(new Paragraph("Date of Birth : "+ day+"-"+month+"-"+year));
        document.add(new Paragraph("Birth Place : " +born));
        document.add(new Paragraph("Nationality : " + nationality));
        document.add(new Paragraph("Current Place : " +currentLocation));
        document.add(new Paragraph("Martial Status : " + martialStatus));
        document.add(new Paragraph("Address : " + address));
        document.add(new Paragraph("Phone Number : " +phoneNumber));
        document.add(new Paragraph("Email : " + emailAddress));
        document.add(new Paragraph("Self Introduction : " + selfInfo));
        document.add(new Paragraph("__________________________________"));

        document.add(new Paragraph("Passport Number : " + passportNumber));
        document.add(new Paragraph("Issue Date : " +passportIssue));
        document.add(new Paragraph("Expiry Date : " + passportExpiry));
        document.add(new Paragraph("ID Card Number  : " + idNumebr));
        document.add(new Paragraph("Issue Date : " +idIssue));
        document.add(new Paragraph("Expiry Date : " + idExpiry));
        document.add(new Paragraph("Licence Number  : " + licenceNumebr));
        document.add(new Paragraph("Issue Date : " +licenceIssue));
        document.add(new Paragraph("Expiry Date : " + licenceExpiry));

        document.close();
}

Answer 1

You can't send data to FirstActivity to ThirdActivity by using intent , You can send data to FirstActivity to SecondActivity by intent again you have to get the data on SecondActivity and again have to send data to ThirdActivity otherwise you will get null data .

Solution 1: Either you can create a Constant class and store data on constant class and get data from Constant class or, Create a POJO class and set Data to POJO and make it Serializable send POJO class to Next of your Activity.

Reference Code :

public class Constants {

    public static ArrayList<LoadDataResult> data = new ArrayList<LoadDataResult>();

  }

When you will get data from User by Edittext get and set to POJO which in Constant class and where do you want to get create reference and get data.

Solution 2 : You have 8 Activities and you want to save all information and create PDF file from MainActivity.java

Here is the solution : Use SharedPreference to save Data , Save data from all of your different activities, and in Your MainActivity when you want just getData from SharePreference , by using this also there is not chance of lost of Data.

FirstActivity.java :

 SharedPreferences pref;
        SharedPreferences.Editor editor;

     pref = (this.getApplicationContext()).getSharedPreferences("USER_DATA", MODE_PRIVATE);

     editor = pref.edit();
                                            editor.putBoolean("login_status", true);
                                            editor.putString("CODE", "" + String.valueOf(obj.get("code")));
                                            editor.putString("NAME", "" + String.valueOf(obj.get("message")));
                                            editor.putString("USER_ID", "" + String.valueOf(obj.get("user id")));
                                            editor.commit();

SecondActivity.java :

     SharedPreferences pref;
            SharedPreferences.Editor editor;

         pref = (this.getApplicationContext()).getSharedPreferences("USER_DATA", MODE_PRIVATE);



                                                editor.putString("ADDRESS", "" + String.valueOf(obj.get("message")));
                                                editor.putString("PHONE", "" + String.valueOf(obj.get("user id")));
                                                editor.commit();

MainActivity.java : When you want to get All Data

SharedPreferences pref;
            SharedPreferences.Editor editor;

         pref = (this.getApplicationContext()).getSharedPreferences("USER_DATA", MODE_PRIVATE);

String name = pref.getString("NAME", "");
String userId = pref.getString("USER_ID", "");
String address = pref.getString("ADDRESS", "");
String phone= pref.getString("PHONE", "");

Answer 2

You can solve the problem by simply send the pojo which contains all of the data in each activity. You only need to pass to pojo from one activity to another activity.

You need to create pojo to something like this:

public class Info implements Serializable {

  private String firstName;
  private String born;
  private String nationality;
  //etc ...

  // Data from another activity:
  private String passportNumber;
  private String idCard;
  private String license;
  //etc ...

  // Data from another activity:
  // etc ...

  // Constructor

  // Setter and Getter
}

Then you can send the data intent with:

public void getting_data_from_fields_and_sending_on_click_listner () {
  Intent sendingData = new Intent (Personal_Information_Activity.this , Selecting_Activity.class);
  Info info = new Info();
  info.setFirstName(fullName.getText().toString());
  info.setBorn(born.getText().toString());
  info.setNationality(nationality.getText().toString());
  // etc

  // Then attach the data to intent.
  sendingData.putExtra("info" , info);

  startActivity(sendingData);
}

Then you get the data info in another activity with:

private Info mInfo;

@Override
public void onCreate(Bundle savedInstanceState) {
  ...
  Intent intent = getIntent();
  mInfo = (Info) intent.getSerializableExtra("info");
  ...
}

And set the data to the Info pojo again:

private void getting_data_from_fields_and_sending_on_click_listner() {

  Intent sendingData = new Intent (Documentation_Activity.this , Selecting_Activity.class);

  mInfo.setPassportNumber(passportNumber.getText().toString());
  mInfo.setIdCard(idCardNumber.getText().toString());
  mInfo.setLicense(licenceNumebr.getText().toString());
  // etc ...

  sendingData.putExtra("info" , mInfo);
  startActivity(sendingData);
}

With the all the above codes, you can safe yourself from headache for remembering all of the extra keys. You also only need to maintain one object, which is the Info object, for all of your activity.