RecyclerView 在 Groupie 中不可见（Kotlin）

Question

I'm trying to use the Groupie library (version 2.1.0) for my RecylerView. In my original app, the view would not be visible at all. I decided to make a dummy app to resolve my issue, and I just cannot get the view to be visible. I feel the solution may be simple since this library is simple to use.

MainActivity.kt:

package com.dmelton.test

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import com.xwray.groupie.GroupAdapter
import com.xwray.groupie.Item
import com.xwray.groupie.ViewHolder
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val adapter = GroupAdapter<ViewHolder>()

        adapter.add(Test())
        adapter.add(Test())
        adapter.add(Test())

        new_recyclerView.adapter = adapter
    }
}

class Test: Item<ViewHolder>() {

    override fun bind(viewHolder: ViewHolder, position: Int) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun getLayout(): Int {
        return R.layout.individual_service
    }

}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">


    <android.support.v7.widget.RecyclerView
            android:layout_width="395dp"
            android:layout_height="715dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent" android:id="@+id/new_recyclerView"/>
</android.support.constraint.ConstraintLayout>

individual_service.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                             android:layout_width="match_parent"
                                             android:layout_height="wrap_content"
                                             xmlns:app="http://schemas.android.com/apk/res-auto">

    <ImageView
            android:id="@+id/imageView_service"
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:layout_marginStart="16dp"
            android:layout_marginTop="8dp"
            android:layout_marginBottom="8dp"
            android:background="@android:color/holo_blue_dark"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:srcCompat="@android:drawable/ic_menu_preferences" />

    <TextView
            android:id="@+id/textView_service_name"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:layout_marginBottom="8dp"
            android:text="Service Name"
            android:textColor="@android:color/black"
            android:textSize="16sp"
            android:textStyle="bold"
            app:layout_constraintBottom_toBottomOf="@+id/imageView_service"
            app:layout_constraintStart_toEndOf="@+id/imageView_service"
            app:layout_constraintTop_toTopOf="@+id/imageView_service" />


    <TextView
            android:id="@+id/textView_service_status"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginBottom="8dp"
            android:text="Status"
            android:textColor="@android:color/black"
            android:textSize="16sp"
            android:textStyle="bold"
            app:layout_constraintBottom_toBottomOf="@+id/imageView_service"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/textView_service_name"
            app:layout_constraintTop_toTopOf="@+id/imageView_service" />

</android.support.constraint.ConstraintLayout>

build.gradle (app)

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.dmelton.test"
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.xwray:groupie:2.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
}

Answer 1

I figured it out. I forgot to add the Layout Manager in my RecyclerView xml block: app:layoutManager="android.support.v7.widget.LinearLayoutManager"

Answer 2

你需要在你的布局文件中添加这个： app:layoutManager="android.support.v7.widget.LinearLayoutManager加上你还需要添加