Android: TextInputLayout ColorStateList.isStateful() throws exception when called from setErrorEnabled()

Question

The custom TextInputLayout results in the below exception when trying to achieve errorState.

 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.content.res.ColorStateList.isStateful()' on a null object reference at com.google.android.material.textfield.TextInputLayout.setBoxStrokeColorStateList(TextInputLayout.java:1103) at tech.********.platform.components.MyCustomTextInput.setErrorEnabled(MyCustomTextInput.kt:81) at com.google.android.material.textfield.TextInputLayout.<init>(TextInputLayout.java:786) at com.google.android.material.textfield.TextInputLayout.<init>(TextInputLayout.java:422) at tech.********.platform.components.MyCustomTextInput.<init>(MyCustomTextInput.kt:38)

XML code to switch app:errorEnabled with binding

<MyCustomTextInput> android:id="@+id/inputPassword" ... app:errorEnabled="@{condition ? true: false}" <MyCustomTextInput/>

trying to achieve error stoke colour without error text as below:

override fun setErrorEnabled(enabled: Boolean) { if (enabled) setBoxStrokeColorStateList(errorColor) else setBoxStrokeColorStateList(defaultColor) super.setErrorEnabled(false) }

complete Layout code below:

class MyCustomTextInput : TextInputLayout { constructor(context: Context) : super(context) constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super( context, attrs, defStyleAttr ) /** * Color states for the default scenario. */ private var defaultColor = ColorStateList( arrayOf( intArrayOf(-R.attr.state_focused, R.attr.state_enabled), intArrayOf(R.attr.state_focused, R.attr.state_enabled), ), intArrayOf(Color.parseColor("#CCCCCC"), Color.parseColor("#164A9C")) ) /** * Color states for the error scenario. */ private var errorColor = ColorStateList( arrayOf( intArrayOf(-R.attr.state_focused, R.attr.state_enabled), intArrayOf(R.attr.state_focused, R.attr.state_enabled) ), intArrayOf(Color.RED, Color.RED) ) init { setBoxStrokeColorStateList(defaultColor) // edit text stroke hintTextColor = defaultColor // edit text content } override fun setErrorIconDrawable(errorIconDrawable: Drawable?) { super.setErrorIconDrawable(null) } override fun setErrorIconTintList(errorIconTintList: ColorStateList?) { super.setErrorIconTintList(errorColor) } override fun setErrorEnabled(enabled: Boolean) { if (enabled) setBoxStrokeColorStateList(errorColor) else setBoxStrokeColorStateList(defaultColor) super.setErrorEnabled(false) } override fun onDraw(canvas: Canvas) { super.onDraw(canvas) } }

Using the same colorState as used in the init().

No, tried calling setErrorEnabled() from the third constructor, didn't help! — Faisal
– Faisal, Commented Jun 19, 2021 at 11:22
Did you see my explanation ? And I added sample of solution at the end (just now). — Artem Viter
– Artem Viter, Commented Jun 19, 2021 at 12:11

Artem Viter · Accepted Answer · 2021-06-19 12:09:22Z

Problem in your overriding of setErrorEnabled method: TextInputLayout call to them from constructor but variables in MyCustomTextInput (child class) not initialized because first the runtime execute a Parent constructor and then child initializers and constructor.

See simple sample bellow. Parent.java:

public class Parent { public Parent() { System.out.println("Parent constructor execution."); System.out.println("Parent call to printErrorMessageLength."); printErrorMessageLength("Parent error."); } public void printErrorMessageLength(String message) { System.out.println("Parent printErrorMessageLength execution."); System.out.println(message.length()); } }

Test.kt:

fun main() { Child() } class Child : Parent { var childErrorMessage = "Child Error" init { println("Child.init, childErrorMessage = $childErrorMessage") } constructor() : super() {} // just for sample override fun printErrorMessageLength(inputMessage: String?) { println("Child printErrorMessageLength execution with inputMessage = $inputMessage") println("${childErrorMessage.length}") super.printErrorMessageLength(inputMessage) } }

result of main executiong:

Parent constructor execution. Parent call to printErrorMessageLength. Child printErrorMessageLength execution with inputMessage = Parent error. Exception in thread "main" java.lang.NullPointerException at Child.printErrorMessageLength(Test.kt:16) at Parent.<init>(Parent.java:6) at Child.<init>(Test.kt:12) at TestKt.main(Test.kt:2) at TestKt.main(Test.kt) Process finished with exit code 1

How I can solve this problem ? - initialize variable if it a null:

/** * Color states for the default scenario. */ private var defaultColor = createDefaultColor() private fun createDefaultColor(): ColorStateList = ColorStateList( arrayOf( intArrayOf(-R.attr.state_focused, R.attr.state_enabled), intArrayOf(R.attr.state_focused, R.attr.state_enabled), ), intArrayOf(Color.parseColor("#CCCCCC"), Color.parseColor("#164A9C")) ) /** * Color states for the error scenario. */ private var errorColor = createErrorColor() private fun createErrorColor(): ColorStateList = ColorStateList( arrayOf( intArrayOf(-R.attr.state_focused, R.attr.state_enabled), intArrayOf(R.attr.state_focused, R.attr.state_enabled) ), intArrayOf(Color.RED, Color.RED) ) override fun setErrorEnabled(enabled: Boolean) { if (enabled) setBoxStrokeColorStateList(errorColor?:createErrorColor()) else setBoxStrokeColorStateList(defaultColor?:createDefaultColor()) super.setErrorEnabled(false) }

Or u can use method like getDefaultColor() instead using variable defaultColor:

private fun getDefaultColor(): ColorStateList { if(defaultColor == null) { defaultColor = createDefaultColor() } return defaultColor }

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