Our question is how to show Parent and Child data from two SQLite DB tables?
We have two tables that are added to two ArrayLists childList and parentList.
Here are the Model Class's for each
class ModelParent {
var idD:Int = 0
var dept:String = ""
var fkD:Int = 0
var children: List<ModelChild>? = null
}
class ModelChild {
var idI:Int = 0
var item:String = ""
var fkI:Int = 0
}
We have two Adapters for each table and will post that code
We are able to iterate through the two ArrayList with this code and display the data in the format we would like to show in the ViewActivity.
fun theGET(){
val db = DBHelper(this)
childList = db.queryITEM()
parentList = db.queryDEPT()
var PL = parentList.size
do {
var DEPT: String = parentList[z].dept
var PARENT_LIST_FK = parentList.get(z).fkD
println("========== Dept " + DEPT + " fkD " + PARENT_LIST_FK)
val FK = PARENT_LIST_FK
childList = db.queryALL(FK)
var CL = childList.size
for (a in 0..CL - 1) {
var CHILD_ITEM = childList[a].item
var CHILD_LIST_FK = childList[a].fkI
println("========== item " + CHILD_ITEM+" fkI "+CHILD_LIST_FK)
}
z++
}
while (z <= PL-1)
}
We will post the View Activity
class ViewActivity : AppCompatActivity() {
lateinit var recyclerView: RecyclerView
private var parentList:List<ModelParent> = ArrayList()
private var childList:List<ModelChild> = ArrayList()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_view)
initRecycler()
}// end onCreate
private fun initRecycler() {
val db = DBHelper(this)
childList = db.queryITEM()
parentList = db.queryDEPT()
recyclerView = rv_parent
recyclerView.apply{
layoutManager = LinearLayoutManager(this@ViewActivity, LinearLayout.VERTICAL, false)
adapter = ViewAdapter(parentList)
adapter = ViewChildAdapter(children = childList)
}
}
}
ViewActivity has this XML file
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
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"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ViewActivity">
<android.support.v7.widget.RecyclerView
android:id="@+id/rv_parent"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</android.support.constraint.ConstraintLayout>
The Two Adapters and coresponding XML files
class ViewAdapter(private val parents:List<ModelParent>):RecyclerView.Adapter<ViewAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.the_view,parent,false)
return ViewHolder(view)
}
override fun getItemCount(): Int {
return parents.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val parent = parents[position]
holder.textView.text = parent.dept
holder.recyclerView.apply {
layoutManager = LinearLayoutManager(holder.recyclerView.context, LinearLayout.VERTICAL, false) as RecyclerView.LayoutManager?
adapter = ViewChildAdapter(parent.children!!)
}
}
inner class ViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView){
val recyclerView : RecyclerView = itemView.rv_child
val textView: TextView = itemView.textView
}
}
class ViewChildAdapter(private val children:List<ModelChild>):RecyclerView.Adapter<ViewChildAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.child_recycler,parent,false)
return ViewHolder(view)
}
override fun getItemCount(): Int {
return children.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val child = children[position]
holder.textView.text = child.item
}
inner class ViewHolder(itemView : View) : RecyclerView.ViewHolder(itemView){
val textView : TextView = itemView.child_textView
}
}
Inflated XML files
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/card_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="2dp"
card_view:cardBackgroundColor="#fff"
card_view:cardCornerRadius="5dp"
card_view:cardElevation="4dp"
card_view:cardUseCompatPadding="true">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/textView"
style="@style/Base.TextAppearance.AppCompat.Subhead"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/rv_child"
android:layout_alignParentTop="true"
android:padding="20dp"
android:background="@color/color_super_lightGray"
android:text="Dept Header"
android:textColor="@color/color_Purple"
android:textSize="24sp"
android:textStyle="bold" />
<android.support.v7.widget.RecyclerView
android:id="@+id/rv_child"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_marginTop="70dp"
android:layout_marginBottom="0dp"
android:orientation="horizontal"
android:paddingLeft="4dp"
android:paddingTop="8dp"
tools:layout_editor_absoluteX="74dp" />
</RelativeLayout>
</android.support.v7.widget.CardView>
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TextView
android:id="@+id/child_textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="32dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:background="@color/color_Transparent"
android:padding="10dp"
android:text="TextView"
android:textColor="@color/color_Black"
android:textSize="20sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
When the ViewActivity is loaded ONLY the childList is displayed.
We have tried various changes and can not display the parent List though using theGET fun the parentList data is displayed so we know it is in the list.
We can run the fun theGET and crate a new ArrayList that seems futile.
Our concern is that the parentList is displayed and then removed when the childList is displayed.
We do not know how to prove this.
So our question is how to show Parent and Child data in a organized fashion in the View Activity?
from kotlin recyclerview data not showing
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