I make extension function in android using kotlin and method from the data type, but my extension function not working properly?

Question

I want to make extension function using TextInputEditText and call addTextChangedListener, but when i run the app and using the feature, my app crash. My goal is to create an extension function addTextChangedListener for the TextInputEditText type so that the length of the code can be more concise

private fun TextInputEditText.textChangedListener() {
        addTextChangedListener(object: TextWatcher{
            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }

            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }

            override fun afterTextChanged(p0: Editable?) {
                findViewById<TextInputLayout>(R.id.regisPasswordLayout).error = null
                findViewById<TextInputLayout>(R.id.regisConfiPasswordLayout).error = null
                findViewById<TextInputLayout>(R.id.regisNamaLayout).error = null
                findViewById<TextInputLayout>(R.id.regisEmailLayout).error = null
            }
        })
}

How I call it

inputPassword.textChangedListener()
inputPasswordConfirmation.textChangedListener()
inputNama.textChangedListener()
inputEmail.textChangedListener()

error logcat which contains my activity

2022-08-31 07:50:45.653 16776-16776/com.kotlin.cloudstorage E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.kotlin.cloudstorage, PID: 16776
    java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.material.textfield.TextInputLayout.setError(java.lang.CharSequence)' on a null object reference
        at com.kotlin.cloudstorage.RegisterActivity$textChangedListener$1.afterTextChanged(RegisterActivity.kt:132)
        at android.widget.TextView.sendAfterTextChanged(TextView.java:10594)
        at android.widget.TextView$ChangeWatcher.afterTextChanged(TextView.java:13581)
        at android.text.SpannableStringBuilder.sendAfterTextChanged(SpannableStringBuilder.java:1277)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:577)
        at androidx.emoji2.text.SpannableBuilder.replace(SpannableBuilder.java:315)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:507)
        at androidx.emoji2.text.SpannableBuilder.replace(SpannableBuilder.java:305)
        at androidx.emoji2.text.SpannableBuilder.replace(SpannableBuilder.java:49)
        at android.text.method.QwertyKeyListener.onKeyDown(QwertyKeyListener.java:228)
        at android.text.method.TextKeyListener.onKeyDown(TextKeyListener.java:141)
        at androidx.emoji2.viewsintegration.EmojiKeyListener.onKeyDown(EmojiKeyListener.java:58)
        at android.widget.TextView.doKeyDown(TextView.java:8466)
        at android.widget.TextView.onKeyDown(TextView.java:8240)
        at android.view.KeyEvent.dispatch(KeyEvent.java:2842)
        at android.view.View.dispatchKeyEvent(View.java:14247)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1959)
        at com.android.internal.policy.DecorView.superDispatchKeyEvent(DecorView.java:476)
        at com.android.internal.policy.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1861)
        at android.app.Activity.dispatchKeyEvent(Activity.java:4085)
        at androidx.core.app.ComponentActivity.superDispatchKeyEvent(ComponentActivity.java:124)

Hello, Please avoid using images to present code. Add the code to the question using the code block option. Also, please provide the crash log. — gioravered
– gioravered, Commented Aug 30, 2022 at 14:02
when you have the crash it is important to read the crash stacktrace as it usually points a finger at what is wrong — Marcin Orlowski
– Marcin Orlowski, Commented Aug 30, 2022 at 14:19

Александр Волошиновский · Accepted Answer · 2022-08-30 14:07:54Z

0

The problem is in findViewById, because your TextInputEditText doesn't containt TextInputLayout also your TextInputEditText can't contains nested view

answered Aug 30, 2022 at 14:07

Александр Волошиновский

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1 Comment

Yosua Haloho Over a year ago

Can you give me some example how to implements it?

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