Sending Data Back to the Main Activity in Android

How to send data back to MainActivity

You can override onBackPressed and pass the data back to the original Activity. But in order to pass it like this, the list must implement Parcelable

@Override
public void onBackPressed() {
    super.onBackPressed();
    Intent intent = new Intent();
    Bundle data = new Bundle();
    data.putParcelableArrayList("someKey", listThatImplementsParcelable);
    intent.putExtras(data);
    setResult(RESULT_OK, intent);
    finish();
}

How do I pass data between Activities in Android application?

The easiest way to do this would be to pass the session id to the signout activity in the Intent you're using to start the activity:

Intent intent = new Intent(getBaseContext(), SignoutActivity.class);
intent.putExtra("EXTRA_SESSION_ID", sessionId);
startActivity(intent);

Access that intent on next activity:

String sessionId = getIntent().getStringExtra("EXTRA_SESSION_ID");

The docs for Intents has more information (look at the section titled "Extras").

How to pass data from 2nd activity to 1st activity when pressed back? - android

Start Activity2 with startActivityForResult and use setResult method for sending data back from Activity2 to Activity1. In Activity1 you will need to override onActivityResult for updating TextView with EditText data from Activity2.

For example:

In Activity1, start Activity2 as:

Intent i = new Intent(this, Activity2.class);
startActivityForResult(i, 1);

In Activity2, use setResult for sending data back:

Intent intent = new Intent();
intent.putExtra("editTextValue", "value_here")
setResult(RESULT_OK, intent);        
finish();

And in Activity1, receive data with onActivityResult:

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 1) {
         if(resultCode == RESULT_OK) {
             String strEditText = data.getStringExtra("editTextValue");
         }     
    }
} 

If you can, also use SharedPreferences for sharing data between Activities.

Android with Kotlin - Sending data back to MainActivity

You made a mistake:

setResult(0, Intent().putExtra("result", num2))

replace 0 (it cancel result) to Activity.RESULT_OK.

Android:Sending data back to MainActivity

setResult() does not move you to any other Activities.

Instead of setResult(Activity.RESULT_OK, returnIntent) you should do this

intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);// If an instance of this Activity already exists, then it will be moved to the front. If an instance does NOT exist, a new instance will be created.
startActivity(intent);

And inyour MainActivity onCreate() you do

Bundle bundle= getIntent().getExtras();
if(bundle !=null){
// get your data here
}

You dont need onActivityResult().
The code is in java since i dont know kotlin, sorry :)

Send data back from one activity to another ANDROID KOTLIN

If you open activities like this: A -> B -> C, and want to retrieve result in activity A from activity C you need to do next steps:

1. Use some common REQUEST_CODE variable, e.g. const val REQUEST_CODE: Int = 400

2. In activity A start activity B using method startActivityForResult(intent, REQUEST_CODE);

3. In activity A override onActivityResult() method:

   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
   
       if (requestCode == Activity.RESULT_OK && requestCode == REQUEST_CODE) {
           val message = data!!.getStringExtra("message")
           Toast.makeText(this, message, Toast.LENGTH_LONG).show()
       } else {
           super.onActivityResult(requestCode, resultCode, data)
       }
   }
   

4. In activity B start activity C using method startActivityForResult(intent, REQUEST_CODE);

5. In activity B override onActivityResult() method:

   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
   
       if (requestCode == Activity.RESULT_OK && requestCode == REQUEST_CODE) {
           makeValidations()
   
           // pass data back to activity A
           setResult(Activity.RESULT_OK, data)
           finish()
       } else {
           super.onActivityResult(requestCode, resultCode, data)
       }
   }
   

6. In activity C to pass data back to activity B:

   val intent = Intent().apply {
       putExtra("message", "This is the qty $scannedQTY")
   }
   setResult(Activity.RESULT_OK, intent)
   finish()
   

How do I pass an 'Exercise' object from one activity back to the main Activity

You can use startActivityForResult instead of startActivity.

Here is example

class MainActivity : Activity(){
    const val REQUEST_CODE = 10001

    override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)

          setContentView(R.layout.activity_main)

          // your implementation
          Intent(this,SomeActivity::class.java).apply {
                // add your data to intent
                startActivityForResult(this,REQUEST_CODE)
          }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        when (requestCode) {
             REQUEST_CODE -> handleResult(resultCode,data)
             else ->super.onActivityResult(requestCode,resultCode,data)
        }
    }

    fun handleResult(result:Int,data:Intent?){
        if(result!=Activity.RESULT_OK) return
        if(data == null) return

        val someData = data.getSerializableExtra("key")
        // do your stuff with someData
    }
}

in your SecondActivity you should use setResult method to pass your data to caller activity( or MainActivity in this case).

class SecondActivity : Activity(){

     // your implementation of activity

    fun sendSuccessResult(someData:Exercise){
        setResult(Activity.RESULT_OK,Intent().apply{ putExtra("key",someData) })
        finish()
    }
}

By calling sendSuccessResult and passing your data, the data will be send back to your MainActivity.

You can read more about it here https://developer.android.com/reference/android/app/Activity

how back to the main activity in android?

try this on you onBackPressed:

Intent intent = new Intent(getApplicationContext(), MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);

this clears the activity stack and opens your main activity. No matter which activity you are, you will always go back to the main activity and all other activities are removed from the stack.

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