checking if the text contains a character and if it is the same as other text Android studio kotlin

Question

I want when I click @button to check if there is an '@' sign in EditText @email and if EditText @password and @password2 have identical text.

I know that I can use the TextWatcher to check if a given character exists, but I don't know how it works.

Answer 1

If you want to check the conditions when a button is clicked, then you don't have to use TextWatcher. You can use the following code to check if the text in the EditText contains the @ character:

//Access the EditText using its id 
val userEmail = findViewById<EditText>(R.id.YOUR_EDITTEXT_ID)
//Get the text entered by the user in the EditText
val userEmailValue = userEmail.text.toString()

//Check if the entered mail id contains the @ character
if (userEmailValue.contains("@")) {
    //Code to be executed if @ exists
} 
else {
    //Code to be executed if @ does not exist
}

Then, if you want to check if the two passwords entered by the user are same, you can use the following code:

//Access the EditTexts as before
val userPswd1 = findViewById<EditText>(R.id.YOUR_PASSWORD_ID1)
val userPswd2 = findViewById<EditText>(R.id.YOUR_PASSWORD_ID2)

//Access the EditText values as before
val userPswdValue1 = userPswd1.text.toString()
val userPswdValue2 = userPswd2.text.toString()

//Check if both the entered passwords are the same
if (userPswdValue1 == userPswdValue2) {
    //Code to be executed if both passwords are same
} else {
    //Code to be executed if both passwords are not same
}

You can put the above code for checking if @ exists and for checking if the passwords are same in a button click listener, like below:

//Access the Button similar to the EditText
val loginBtn = findViewById<Button>(R.id.YOUR_BUTTON_ID)

//Execute code when the button is clicked
button.setOnClickListener {
     //Your code
}

Finally, combining the entire code together:

//Access the Button
val loginBtn = findViewById<Button>(R.id.YOUR_BUTTON_ID)
//Access the EditTexts
val userEmail = findViewById<EditText>(R.id.YOUR_EDITTEXT_ID)
val userPswd1 = findViewById<EditText>(R.id.YOUR_PASSWORD_ID1)
val userPswd2 = findViewById<EditText>(R.id.YOUR_PASSWORD_ID2)

//Execute code when the button is clicked
button.setOnClickListener {    
    //Get the text entered by the user in the EditText
    val userEmailValue = userEmail.text.toString()

    //Check if the entered mail id contains the @ character
    if (userEmailValue.contains("@")) {
        //Code to be executed if @ exists
    } 
    else {
        //Code to be executed if @ does not exist
    }

    //Get the passwords entered by the user
    val userPswdValue1 = userPswd1.text.toString()
    val userPswdValue2 = userPswd2.text.toString()

    //Check if both the entered passwords are the same
    if (userPswdValue1 == userPswdValue2) {
        //Code to be executed if both passwords are same
    } 
    else {
        //Code to be executed if both passwords are not same
   }
}

You can TextWatcher if you want to execute the code as soon as the user starts typing in the EditText.

Answer 2

So let us break the task; in order to see if the @ symbol is present in the text, you can do the following:

val emailEditText = findViewById<EditText>(R.id.email)
val email = emailEditText.text.toString()

if (email.contains("@")) {
    // '@' symbol is present in the email EditText
} else {
    // '@' symbol is not present in the email EditText
}

Now in order to see if password edit texts have the same text, we can do the following:

// you can use data binding here also
val passwordEditText = findViewById<EditText>(R.id.password)
val password = passwordEditText.text.toString()

val password2EditText = findViewById<EditText>(R.id.password2)
val password2 = password2EditText.text.toString()

if (password == password2) {
    // passwords match
} else {
    // passwords do not match
}

So we can combine everything when the user click on your button like that:

val emailEditText = findViewById<EditText>(R.id.email)
val passwordEditText = findViewById<EditText>(R.id.password)
val password2EditText = findViewById<EditText>(R.id.password2)
val button = findViewById<Button>(R.id.button)

button.setOnClickListener {
    
    val email = emailEditText.text.toString()

    if (email.contains("@")) {
        // '@' symbol is present in the email EditText
    } else {
        // '@' symbol is not present in the email EditText
        Toast.makeText(this, "Email should contain '@' symbol", Toast.LENGTH_SHORT).show()
        return@setOnClickListener
    }

    val password = passwordEditText.text.toString()
    val password2 = password2EditText.text.toString()

    if (password == password2) {
        // passwords match
        Toast.makeText(this, "Passwords match", Toast.LENGTH_SHORT).show()
    } else {
        // passwords do not match
        Toast.makeText(this, "Passwords do not match", Toast.LENGTH_SHORT).show()
    }
}

You don't have to use TextWatcher when you want to handle only click events, but if you want to make continuous observing of the EditText, then you should use it!