Explicit intent example in jetpack

Here’s an example of using Explicit Intent in Jetpack Compose to navigate between two activities.

Step 1: Create Two Activities

MainActivity.kt

This is the starting activity that launches SecondActivity.

package com.example.explicitintentexample

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("message", "Hello from MainActivity!")
                        }
                        startActivity(intent)
                    },
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Text(text = "Go to Second Activity")
                }
            }
        }
    }
}

SecondActivity.kt

This activity receives the intent and displays the passed message.

package com.example.explicitintentexample

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)
        val message = intent.getStringExtra("message") ?: "No message received"

        setContent {
            SecondScreen(message)
        }
    }

    @Composable
    fun SecondScreen(message: String) {
        Scaffold(
            topBar = {
                TopAppBar(title = { Text("Second Activity") })
            }
        ) { padding ->
            Column(
                modifier = Modifier
                    .fillMaxSize()
                    .padding(padding)
                    .padding(16.dp),
                verticalArrangement = Arrangement.Center
            ) {
                Text(text = "Received Message:", style = MaterialTheme.typography.titleMedium)
                Spacer(modifier = Modifier.height(8.dp))
                Text(text = message, style = MaterialTheme.typography.bodyLarge)
            }
        }
    }
}

Key Steps in the Code:

1. MainActivity.kt:

• Created a button using Jetpack Compose.
• On button click, used an explicit intent to navigate to SecondActivity and passed data using putExtra.

1. SecondActivity.kt:

• Retrieved the passed data using intent.getStringExtra.
• Displayed the received message in the UI using Jetpack Compose.

Output:

1. Main Activity: Displays a button labeled “Go to Second Activity.”
2. Second Activity: Displays the message “Hello from MainActivity!” passed from the first activity.