Can't use method direct in xml

Question

Android Studio 3.6

in build.gradle:

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'

android {
    viewBinding {
        enabled = true
    }
    dataBinding {
        enabled = true
}

MainActivity:

  import android.os.Bundle
    import androidx.appcompat.app.AppCompatActivity
    import com.myproject.android.androidtestproject.BuildConfig
    import com.myproject.android.androidtestproject.R
    import com.myproject.android.androidtestproject.databinding.MainActivityBinding

import com.myproject.android.androidtestproject.util.Debug
    class MainActivity : AppCompatActivity() {
        private lateinit var binding: MainActivityBinding
        private val TAG = MainActivity::class.java.name

        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.main_activity)
            binding = MainActivityBinding.inflate(layoutInflater)
            val view = binding.root
            setContentView(view)
            init()
    }

I want to use DateUtil.getCurrrentDateAsString() direct in xml.

So I use this in layout main_activity.xml

android:text='@{DateUtil.getCurrrentDateAsString()}'

Here layout:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <import type="com.myproject.android.androidtestproject.util.DateUtil" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/appNameTextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/default_margin"
            android:gravity="center"
            android:textSize="18sp"
            app:layout_constraintBottom_toTopOf="@+id/loadListButton"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/currentDateTextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text='@{DateUtil.getCurrrentDateAsString()}'
            app:layout_constraintBottom_toTopOf="@+id/loadListButton"
            app:layout_constraintEnd_toEndOf="@+id/appNameTextView"
            app:layout_constraintStart_toStartOf="@+id/appNameTextView"
            app:layout_constraintTop_toBottomOf="@+id/appNameTextView" />

        <Button
            android:id="@+id/loadListButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/default_margin"
            android:layout_marginBottom="@dimen/default_margin"
            android:text="@string/load_list"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="@+id/appNameTextView"
            app:layout_constraintStart_toStartOf="parent" />


    </androidx.constraintlayout.widget.ConstraintLayout>

</layout>

And here DateUtil.kt :

import java.text.SimpleDateFormat
import java.util.*

class DateUtil {
    companion object {
        const val DEFAULT_DATE_FORMAT = "dd.MM.yyyy"
        const val ISO_DATE_FORMAT = "yyyy-MM-dd"
        @JvmStatic
        fun getCurrrentDateAsString(pattern: String = DEFAULT_DATE_FORMAT): String {
            val currentDate = getCurrentDate()
            val currentDateAsString = getDateAsString(currentDate, pattern)
            return currentDateAsString
        }

        fun getCurrentDate(): Date {
            return Date()
        }

        // if pattern is null then will be use defaultDTCDateFormat
        fun getDateAsString(date: Date?, pattern: String = DEFAULT_DATE_FORMAT): String {
            if (date == null) {
                return ""
            }
            var sdf: SimpleDateFormat? = null
            return try {
                sdf = SimpleDateFormat(pattern)
                sdf.format(date)
            } catch (ex: IllegalArgumentException) {
                sdf = SimpleDateFormat(pattern)
                sdf.format(date)
            }
        }
    }
}

But when I try to build I get error:

> Task :app:validateSigningDebug UP-TO-DATE

> Task :app:kaptDebugKotlin FAILED
AndroidTestProject/android/AndroidTestProject/app/build/generated/source/kapt/debug/com/myproject/android/androidtestproject/DataBinderMapperImpl.java:9: error: cannot find symbol
import com.gmail.alexei28.android.androidtestproject.databinding.MainActivityBindingImpl;
                                                                ^
  symbol:   class MainActivityBindingImpl
  location: package com.gmail.alexei28.android.androidtestproject.databinding
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:kaptDebugKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptExecution
   > java.lang.reflect.InvocationTargetException (no error message)

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 10s

Answer 1

I think, your problem occurs because method you call has parameter ("pattern"), you don't put it inside your xml.

Despite it has default value DataBinding can't resolve that.

Maybe there are more elegant decisions but you can try these:

1. Change your xml code to:

   android:text=@{DateUtil.getCurrrentDateAsString(DateUtil. DEFAULT_DATE_FORMAT)}'

2. To add some DataBinding adapter to invoke your method from the code