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How to Validate TextFields in a Login Form in Android using Jetpack Compose?

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In Android, TextField validation means checking if the user inputs are sufficient for a task to start or call a function. Generally, validation takes place in forms where the user is required to give mandatory inputs (fields marked with an asterisk). The most common examples of such forms are registration or sign-up forms and login forms.

Login Form

 

In this article, we will show you how you could Validate TextFields in a Login Form in Android using Jetpack Compose. Follow the below steps once the IDE is ready.

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. While choosing the template, select Empty Compose Activity. If you do not find this template, try upgrading the Android Studio to the latest version. We demonstrated the application in Kotlin, so make sure you select Kotlin as the primary language while creating a New Project.

Step 2: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin




package com.geeksforgeeks.jcvalidation
  
import android.os.Bundle
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
  
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            // Calling the composable function
            // to display element and its contents
            MainContent()
        }
    }
}
  
// Creating a composable
// function to display Top Bar
@Composable
fun MainContent() {
    Scaffold(
        topBar = { TopAppBar(title = { Text("GFG | Validation", color = Color.White) }, backgroundColor = Color(0xff0f9d58)) },
        content = { MyContent() }
    )
}
  
// Creating a composable function
// to create two TextFields
// Calling this function as content
// in the above function
@Composable
fun MyContent(){
  
    // fetching local context
    val mContext = LocalContext.current
  
    Column(
        Modifier
            .fillMaxSize()
            .padding(20.dp), horizontalAlignment = Alignment.CenterHorizontally, verticalArrangement = Arrangement.Center) {
  
        // Declaring two string values 
        // for storing username and password
        val mUsername = remember { mutableStateOf("") }
        val mPassword = remember { mutableStateOf("") }
  
          // Creating two outlined text fields for 
          // fetching username and password from the user        
          OutlinedTextField(
            value = mUsername.value,
            onValueChange = { mUsername.value = it },
            label = { Text(text = "Username") },
            modifier = Modifier.fillMaxWidth()
        )
  
        OutlinedTextField(
            value = mPassword.value,
            onValueChange = { mPassword.value = it },
            label = { Text(text = "Password") },
            modifier = Modifier.fillMaxWidth()
        )
  
        // Adding a Spacer
        Spacer(modifier = Modifier.height(100.dp))
  
        // Button onclick would check
        // for the below conditions
        Button(onClick = {
            if(mUsername.value.isEmpty() and mPassword.value.isNotEmpty()){
                Toast.makeText(mContext, "Username is Empty", Toast.LENGTH_SHORT).show()
            }
            if (mPassword.value.isEmpty() and mUsername.value.isNotEmpty()){
                Toast.makeText(mContext, "Password is Empty", Toast.LENGTH_SHORT).show()
            }
            if(mUsername.value.isEmpty() and mPassword.value.isEmpty()){
                Toast.makeText(mContext, "Username and Password are Empty", Toast.LENGTH_SHORT).show()
            }
            if(mUsername.value.isNotEmpty() and mPassword.value.isNotEmpty()){
                Toast.makeText(mContext, "Successfully Validated", Toast.LENGTH_SHORT).show()
            }
        },
            colors = ButtonDefaults.buttonColors(backgroundColor = Color(0XFF0F9D58)),
        ) {
            Text("Next", color = Color.White)
        }
    }
}
  
// For displaying preview in 
// the Android Studio IDE emulator
@Preview(showBackground = true)
@Composable
fun DefaultPreview() {
    MainContent()
}


Output:

You can see that we are able to validate the TextFields using various conditions.



Last Updated : 29 Mar, 2022
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