Data Transfer between activities

Transferring data between activities in Android can be achieved using Intent. Here’s a comprehensive example of how to send and receive data between two activities.

Example: Data Transfer Between Two Activities

Step 1: Create Two Activities

MainActivity.kt

This activity sends data to SecondActivity.

package com.example.datatransferexample

import android.content.Intent
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material3.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MainScreen()
        }
    }

    @Composable
    fun MainScreen() {
        Scaffold(
            topBar = {
                TopAppBar(title = { Text("Main Activity") })
            }
        ) { padding ->
            Column(
                modifier = Modifier
                    .fillMaxSize()
                    .padding(padding)
                    .padding(16.dp),
                verticalArrangement = Arrangement.Center
            ) {
                Button(
                    onClick = {
                        val intent = Intent(this@MainActivity, SecondActivity::class.java).apply {
                            putExtra("name", "John Doe")
                            putExtra("age", 25)
                            putExtra("isStudent", true)
                        }
                        startActivity(intent)
                    },
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Text(text = "Send Data to Second Activity")
                }
            }
        }
    }
}

SecondActivity.kt

This activity receives the data from MainActivity.

package com.example.datatransferexample

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material3.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

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

        // Retrieve the data sent from MainActivity
        val name = intent.getStringExtra("name") ?: "Unknown"
        val age = intent.getIntExtra("age", -1)
        val isStudent = intent.getBooleanExtra("isStudent", false)

        setContent {
            SecondScreen(name, age, isStudent)
        }
    }

    @Composable
    fun SecondScreen(name: String, age: Int, isStudent: Boolean) {
        Scaffold(
            topBar = {
                TopAppBar(title = { Text("Second Activity") })
            }
        ) { padding ->
            Column(
                modifier = Modifier
                    .fillMaxSize()
                    .padding(padding)
                    .padding(16.dp),
                verticalArrangement = Arrangement.Center
            ) {
                Text(text = "Name: $name", style = MaterialTheme.typography.bodyLarge)
                Spacer(modifier = Modifier.height(8.dp))
                Text(text = "Age: $age", style = MaterialTheme.typography.bodyLarge)
                Spacer(modifier = Modifier.height(8.dp))
                Text(
                    text = "Is Student: ${if (isStudent) "Yes" else "No"}",
                    style = MaterialTheme.typography.bodyLarge
                )
            }
        }
    }
}

Key Concepts in the Code

1. Sending Data (MainActivity):

• Used the Intent.putExtra() method to pass key-value pairs (e.g., name, age, isStudent).
• Started the second activity using startActivity().

1. Receiving Data (SecondActivity):

• Used the intent.getStringExtra(), intent.getIntExtra(), and intent.getBooleanExtra() methods to retrieve the data.
• Displayed the data in the UI.

Expected Output

1. Main Activity:

• Displays a button: “Send Data to Second Activity”.
• Clicking the button sends data (name, age, isStudent) to SecondActivity.

1. Second Activity:

• Displays the transferred data:
  Name: John Doe Age: 25 Is Student: Yes

Notes:

• Data Types Supported: String, Int, Boolean, ArrayList, Parcelable, Serializable.
• For complex objects, use Parcelable or Serializable.